Glycogen storage disease type II, also called Pompe disease, is an
autosomal recessive
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...
metabolic disorder
A metabolic disorder is a disorder that negatively alters the body's processing and distribution of macronutrients, such as proteins, fats, and carbohydrates. Metabolic disorders can happen when abnormal chemical reactions in the body alter the ...
which damages muscle and nerve cells throughout the body. It is caused by an accumulation of
glycogen
Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. The polysaccharide structure represents the main storage form of glucose in the body.
Glycogen functions as one o ...
in the
lysosome
A lysosome () is a membrane-bound organelle found in many animal cells. They are spherical vesicles that contain hydrolytic enzymes that can break down many kinds of biomolecules. A lysosome has a specific composition, of both its membrane prot ...
due to deficiency of the lysosomal
acid alpha-glucosidase
Acid alpha-glucosidase, also called α-1,4-glucosidase and acid maltase, is an enzyme () that helps to break down glycogen in the lysosome. It is functionally similar to glycogen debranching enzyme, but is on a different chromosome, processed diff ...
enzyme. It is the only
glycogen storage disease
A glycogen storage disease (GSD, also glycogenosis and dextrinosis) is a metabolic disorder caused by an enzyme deficiency affecting glycogen synthesis, glycogen breakdown, or glucose breakdown, typically in muscles and/or liver cells.
GSD has ...
with a defect in lysosomal metabolism, and the first glycogen storage disease to be identified, in 1932 by the Dutch pathologist
J. C. Pompe.
The build-up of glycogen causes progressive muscle weakness (
myopathy
In medicine, myopathy is a disease of the muscle in which the muscle fibers do not function properly. This results in muscular weakness. ''Myopathy'' means muscle disease (Greek : myo- ''muscle'' + patheia '' -pathy'' : ''suffering''). This meani ...
) throughout the body and affects various body tissues, particularly in the
heart
The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide t ...
,
skeletal muscle
Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...
s,
liver
The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...
and the
nervous system
In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes th ...
.
Signs and symptoms
Newborn
The infantile form usually comes to medical attention within the first few months of life. The usual presenting features are
cardiomegaly
Cardiomegaly (sometimes megacardia or megalocardia) is a medical condition in which the heart is enlarged. As such, it is more commonly referred to simply as "having an enlarged heart". It is usually the result of underlying conditions that make t ...
(92%),
hypotonia
Hypotonia is a state of low muscle tone (the amount of tension or resistance to stretch in a muscle), often involving reduced muscle strength. Hypotonia is not a specific medical disorder, but a potential manifestation of many different diseases a ...
(88%),
cardiomyopathy
Cardiomyopathy is a group of diseases that affect the heart muscle. Early on there may be few or no symptoms. As the disease worsens, shortness of breath, feeling tired, and swelling of the legs may occur, due to the onset of heart failure. A ...
(88%), respiratory distress (78%), muscle weakness (63%), feeding difficulties (57%) and
failure to thrive
Failure to thrive (FTT), also known as weight faltering or faltering growth, indicates insufficient weight gain or absence of appropriate physical growth in children. FTT is usually defined in terms of weight, and can be evaluated either by a low ...
(50%).
The main clinical findings include
floppy baby appearance, delayed motor milestones, and feeding difficulties. Moderate hepatomegaly may or may not be present. Facial features include
macroglossia
Macroglossia is the medical term for an unusually large tongue. Severe enlargement of the tongue can cause cosmetic and functional difficulties in speaking, eating, swallowing and sleeping. Macroglossia is uncommon, and usually occurs in children. ...
, wide open mouth, wide open eyes, nasal flaring (due to respiratory distress), and poor facial muscle tone. Cardiopulmonary involvement is manifested by increased respiratory rate, use of accessory muscles for respiration, recurrent chest infections, decreased air entry in the left lower zone (due to cardiomegaly), arrhythmias, and evidence of heart failure.
Before developing a treatment, median age at death in untreated cases was 8.7 months, usually due to cardiorespiratory failure; However, this outcome is drastically changed since treatment has been available, improving with early access to treatment.
Late onset form
This form differs from the infantile principally in the relative lack of cardiac involvement. The onset is more insidious and has a slower progression. Cardiac involvement may occur but is milder than in the infantile form. Skeletal involvement is more prominent with a predilection for the lower limbs.
Late onset features include impaired
cough
A cough is a sudden expulsion of air through the large breathing passages that can help clear them of fluids, irritants, foreign particles and microbes. As a protective reflex, coughing can be repetitive with the cough reflex following three pha ...
, recurrent chest infections,
hypotonia
Hypotonia is a state of low muscle tone (the amount of tension or resistance to stretch in a muscle), often involving reduced muscle strength. Hypotonia is not a specific medical disorder, but a potential manifestation of many different diseases a ...
, progressive muscle weakness, delayed motor milestones, difficulty swallowing or chewing and reduced vital capacity.
Prognosis depends on the age of onset of symptoms with a better prognosis being associated with later onset disease.
Cause
It has an autosomal recessive inheritance pattern. This means the defective gene is located on an
autosome
An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosome, allosomal (sex chromosome) pairs, which may have different structures. The DNA in au ...
, and two faulty copies of the gene — one from each parent — are required to be born with the disorder. As with all cases of autosomal recessive inheritance, children have a 1 in 4 chance of inheriting the disorder when both parents carry the defective gene, and although both parents carry one copy of the defective gene, they are usually not affected by the disorder.
The disease is caused by a mutation in a
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
(
acid alpha-glucosidase
Acid alpha-glucosidase, also called α-1,4-glucosidase and acid maltase, is an enzyme () that helps to break down glycogen in the lysosome. It is functionally similar to glycogen debranching enzyme, but is on a different chromosome, processed diff ...
: also known as acid maltase) on long arm of
chromosome 17
Chromosome 17 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 17 spans more than 83 million base pairs (the building material of DNA) and represents between 2.5 and 3% of the total D ...
at 17q25.2-q25.3 (base pair 75,689,876 to 75,708,272). The number of mutations described is currently (in 2010) 289 with 67 being non-pathogenic mutations and 197 pathogenic mutations. The remainder are still being evaluated for their association with disease.
The gene spans approximately 20 kb and contains 20
exon
An exon is any part of a gene that will form a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. The term ''exon'' refers to both the DNA sequence within a gene and to the corresponding sequen ...
s with the first exon being noncoding. The coding sequence of the putative catalytic site domain is interrupted in the middle by an intron of 101 bp. The promoter has features characteristic of a
housekeeping gene
In molecular biology, housekeeping genes are typically constitutive genes that are required for the maintenance of basic cellular function, and are expressed in all cells of an organism under normal and patho-physiological conditions. Although ...
. The GC content is high (80%) and distinct TATA and CCAAT motifs are lacking.
Most cases appear to be due to three mutations. A
transversion
Transversion, in molecular biology, refers to a point mutation in DNA in which a single (two ring) purine ( A or G) is changed for a (one ring) pyrimidine ( T or C), or vice versa. A transversion can be spontaneous, or it can be caused by ioni ...
(T → G) mutation is the most common among adults with this disorder. This mutation interrupts a site of
RNA splicing
RNA splicing is a process in molecular biology where a newly-made precursor messenger RNA (pre-mRNA) transcript is transformed into a mature messenger RNA (mRNA). It works by removing all the introns (non-coding regions of RNA) and ''splicing'' b ...
.
The gene encodes a protein—
acid alpha-glucosidase
Acid alpha-glucosidase, also called α-1,4-glucosidase and acid maltase, is an enzyme () that helps to break down glycogen in the lysosome. It is functionally similar to glycogen debranching enzyme, but is on a different chromosome, processed diff ...
(EC 3.2.1.20)—which is a lysosomal
hydrolase
Hydrolase is a class of enzyme that commonly perform as biochemical catalysts that use water to break a chemical bond, which typically results in dividing a larger molecule into smaller molecules. Some common examples of hydrolase enzymes are este ...
. The protein is an
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...
that normally degrades the alpha -1,4 and alpha -1,6 linkages in
glycogen
Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. The polysaccharide structure represents the main storage form of glucose in the body.
Glycogen functions as one o ...
,
maltose
}
Maltose ( or ), also known as maltobiose or malt sugar, is a disaccharide formed from two units of glucose joined with an α(1→4) bond. In the isomer isomaltose, the two glucose molecules are joined with an α(1→6) bond. Maltose is the two- ...
and
isomaltose
Isomaltose is a disaccharide similar to maltose, but with a α-(1-6)-linkage instead of the α-(1-4)-linkage. Both of the sugars are dimers of glucose, which is a pyranose sugar. Isomaltose is a reducing sugar. Isomaltose is produced when high ma ...
and is required for the degradation of 1–3% of cellular
glycogen
Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. The polysaccharide structure represents the main storage form of glucose in the body.
Glycogen functions as one o ...
. The deficiency of this enzyme results in the accumulation of structurally normal glycogen in
lysosome
A lysosome () is a membrane-bound organelle found in many animal cells. They are spherical vesicles that contain hydrolytic enzymes that can break down many kinds of biomolecules. A lysosome has a specific composition, of both its membrane prot ...
s and
cytoplasm
In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The ...
in affected individuals. Excessive glycogen storage within lysosomes may interrupt normal functioning of other
organelle
In cell biology, an organelle is a specialized subunit, usually within a cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as organs are to the body, hence ''organelle,'' the ...
s and lead to cellular injury.
A putative homologue—acid alpha-glucosidase-related gene 1—has been identified in the
nematode
The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...
''
Caenorhabditis elegans
''Caenorhabditis elegans'' () is a free-living transparent nematode about 1 mm in length that lives in temperate soil environments. It is the type species of its genus. The name is a blend of the Greek ''caeno-'' (recent), ''rhabditis'' (ro ...
''.
Diagnosis
In the early-onset form, an infant will present with poor feeding causing failure to thrive, or with difficulty breathing. The usual initial investigations include chest X ray,
electrocardiogram and
echocardiography
An echocardiography, echocardiogram, cardiac echo or simply an echo, is an ultrasound of the heart.
It is a type of medical imaging of the heart, using standard ultrasound or Doppler ultrasound.
Echocardiography has become routinely used in t ...
. Typical findings are those of an enlarged heart with non specific conduction defects. Biochemical investigations include
serum creatine kinase
Creatine kinase (CK), also known as creatine phosphokinase (CPK) or phosphocreatine kinase, is an enzyme () expressed by various tissues and cell types. CK catalyses the conversion of creatine and uses adenosine triphosphate (ATP) to create phosp ...
(typically increased 10 fold) with lesser elevations of the serum
aldolase
Fructose-bisphosphate aldolase (), often just aldolase, is an enzyme catalyzing a reversible reaction that splits the aldol, fructose 1,6-bisphosphate, into the triose phosphates dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate ( ...
,
aspartate transaminase
Aspartate transaminase (AST) or aspartate aminotransferase, also known as AspAT/ASAT/AAT or (serum) glutamic oxaloacetic transaminase (GOT, SGOT), is a pyridoxal phosphate (PLP)-dependent transaminase enzyme () that was first described by Arthur ...
,
alanine transaminase
Alanine transaminase (ALT) is a transaminase enzyme (). It is also called alanine aminotransferase (ALT or ALAT) and was formerly called serum glutamate-pyruvate transaminase or serum glutamic-pyruvic transaminase (SGPT) and was first character ...
and
lactic dehydrogenase
Lactate dehydrogenase (LDH or LD) is an enzyme found in nearly all living cells. LDH catalyzes the conversion of lactate to pyruvate and back, as it converts NAD+ to NADH and back. A dehydrogenase is an enzyme that transfers a hydride from on ...
. Diagnosis is made by estimating the acid alpha glucosidase activity in either skin biopsy (
fibroblast
A fibroblast is a type of cell (biology), biological cell that synthesizes the extracellular matrix and collagen, produces the structural framework (Stroma (tissue), stroma) for animal Tissue (biology), tissues, and plays a critical role in wound ...
s), muscle biopsy (muscle cells) or in white blood cells. The choice of sample depends on the facilities available at the diagnostic laboratory.
In the late-onset form, an adult will present with gradually progressive arm and leg weakness, with worsening respiratory function.
Electromyography
Electromyography (EMG) is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph to produce a record called an electromyogram. An electromyog ...
may be used initially to distinguish Pompe from other causes of limb weakness. The findings on biochemical tests are similar to those of the infantile form, with the caveat that the creatine kinase may be normal in some cases. The diagnosis is by estimation of the enzyme activity in a suitable sample.
On May 17, 2013, the Secretary's Discretionary Advisory Committee on Heritable Diseases in Newborns and Children
DACHDNC approved a recommendation to the
Secretary of Health and Human Services
The United States secretary of health and human services is the head of the United States Department of Health and Human Services, and serves as the principal advisor to the president of the United States on all health matters. The secretary is ...
to add Pompe to the Recommended Uniform Screening Panel
RUSP. The HHS secretary must first approve the recommendation before the disease is formally added to the panel.
Classification
There are exceptions, but levels of alpha-glucosidase determines the type of GSD II an individual may have. More alpha glucosidase present in the individual's muscles means symptoms occur later in life and progress more slowly. GSD II is broadly divided into two onset forms based on the age symptoms occur.
Infantile-onset form is usually diagnosed at 4–8 months; muscles appear normal but are limp and weak preventing the child from lifting their head or rolling over. As the disease progresses, heart muscles thicken and progressively fail. Without treatment, death usually occurs due to heart failure and respiratory weakness.
Late or later onset form occurs later than one to two years and progresses more slowly than Infantile-onset form. One of the first symptoms is a progressive decrease in muscle strength starting with the legs and moving to smaller muscles in the trunk and arms, such as the diaphragm and other muscles required for breathing. Respiratory failure is the most common cause of death. Enlargement of the heart muscles and rhythm disturbances are not significant features but do occur in some cases.
Treatment
Cardiac and respiratory complications are treated symptomatically. Physical and occupational therapy may be beneficial for some patients. Alterations in diet may provide temporary improvement but will not alter the course of the disease. Genetic counseling can provide families with information regarding risk in future pregnancies.
On April 28, 2006, the US
Food and Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
(FDA) approved a
biologic license application
A biologics license application (BLA) is defined by the U.S. Food and Drug Administration (FDA) as follows:
The biologics license application is a request for permission to introduce, or deliver for introduction, a biologic product into inters ...
(BLA) for
alglucosidase alfa
Alglucosidase alfa, sold under the brand name Myozyme among others, is an enzyme replacement therapy (ERT) orphan drug for treatment of Pompe disease (Glycogen storage disease type II), a rare lysosomal storage disorder (LSD).
Chemically speaki ...
, rhGAA (Myozyme), the first treatment for patients with Pompe disease, developed by a team of
Duke University
Duke University is a private research university in Durham, North Carolina. Founded by Methodists and Quakers in the present-day city of Trinity in 1838, the school moved to Durham in 1892. In 1924, tobacco and electric power industrialist James ...
researchers. This was based on
enzyme replacement therapy
Enzyme replacement therapy (ERT) is a medical treatment which replaces an enzyme that is deficient or absent in the body. Usually, this is done by giving the patient an intravenous (IV) infusion of a solution containing the enzyme.
ERT is availab ...
using biologically active recombinant human alglucosidase alfa produced in Chinese Hamster Ovary cells. Myozyme falls under the FDA
orphan drug
An orphan drug is a pharmaceutical agent developed to treat medical conditions which, because they are so rare, would not be profitable to produce without government assistance. The conditions are referred to as orphan diseases.
The assignment of ...
designation and was approved under a
priority review
Priority review is a program of the United States Food and Drug Administration (FDA) to expedite the review process for drugs that are expected to have a particularly great impact on the treatment of a disease. The priority review voucher program ...
.
The FDA approved Myozyme for administration by intravenous infusion of the solution.
The safety and efficacy of Myozyme were assessed in two separate clinical trials in 39 infantile-onset patients with Pompe disease ranging in age from 1 month to 3.5 years at the time of the first infusion.
Myozyme treatment prolongs ventilator-free survival and overall survival. Early diagnosis and early treatment leads to much better outcomes. The treatment is not without side effects which include fever, flushing, skin rash, increased heart rate and even shock; these conditions, however, are usually manageable.
Myozyme costs an average of US$300,000 a year and must be taken for the patients' entire life, so some American health insurers have refused to pay for it. In August 2006,
Health Canada
Health Canada (HC; french: Santé Canada, SC)Health Canada is the applied title under the Federal Identity Program; the legal title is Department of Health (). is the Structure of the Canadian federal government#Departments, with subsidiary unit ...
approved Myozyme for the treatment of Pompe disease. In June 2007, the Canadian Common Drug Review issued their recommendations regarding public funding for Myozyme therapy. Their recommendation was to provide funding to treat a tiny subset of Pompe patients (Infants less one year of age with cardiomyopathy).
In May 2010, the FDA approved
Lumizyme
Alglucosidase alfa, sold under the brand name Myozyme among others, is an enzyme replacement therapy (ERT) orphan drug for treatment of Pompe disease (Glycogen storage disease type II), a rare disease, rare lysosomal storage disorder (LSD).
Chem ...
for the treatment of late-onset Pompe disease.
Lumizyme and Myozyme have the same generic ingredient (alglucosidase alfa) and manufacturer (Genzyme Corporation).
The difference between these two products is in the manufacturing process.
Myozyme is made using a 160-L
bioreactor
A bioreactor refers to any manufactured device or system that supports a biologically active environment. In one case, a bioreactor is a vessel in which a chemical reaction, chemical process is carried out which involves organisms or biochemistry, ...
, while Lumizyme uses a 4000-L bioreactor. Because of the difference in the manufacturing process, the FDA claims that the two products are biologically different. Myozyme is FDA approved for replacement therapy for infantile-onset Pompe disease.
In July 2021, the
European Medicines Agency
The European Medicines Agency (EMA) is an agency of the European Union (EU) in charge of the evaluation and supervision of medicinal products. Prior to 2004, it was known as the European Agency for the Evaluation of Medicinal Products or Euro ...
(EMA) recommended the authorization of
avalglucosidase alfa.
Avalglucosidase alfa (Nexviazyme) was approved for medical use in the United States in August 2021,
[ ] and in the European Union in June 2022.
In December 2022, the EMA recommended the authorization of
cipaglucosidase alfa.
Prognosis
The prognosis for individuals with Pompe disease varies according to the onset and severity of symptoms, along with lifestyle factors. Without treatment the infantile form (which can typically be predicted by mutation analysis) of the disease is particularly lethal - in these cases time to get on treatment is critical, with evidence that days (not weeks or months) matter.
Myozyme (alglucosidase alfa) is a recombinant form of the human enzyme
acid alpha-glucosidase
Acid alpha-glucosidase, also called α-1,4-glucosidase and acid maltase, is an enzyme () that helps to break down glycogen in the lysosome. It is functionally similar to glycogen debranching enzyme, but is on a different chromosome, processed diff ...
, and is also currently being used to replace the missing enzyme. In a study which included the largest cohort of patients with Pompe disease treated with enzyme replacement therapy (ERT) to date findings showed that Myozyme treatment clearly prolongs ventilator-free survival and overall survival in patients with infantile-onset Pompe disease as compared to an untreated historical control population. Furthermore, the study demonstrated that initiation of ERT prior to 6 months of age, which could be facilitated by newborn screening, shows great promise to reduce the mortality and disability associated with this devastating disorder. Taiwan and several states in the United States have started the newborn screening and results of such regimen in early diagnosis and early initiation of the therapy have dramatically improved the outcome of the disease; many of these babies have reached the normal motor developmental milestones.
Another factor affecting the treatment response is generation of antibodies against the infused enzyme, which is particularly severe in Pompe infants who have complete deficiency of the acid alpha-glucosidase.
Immune tolerance therapy to eliminate these antibodies has improved the treatment outcome.
A Late Onset Treatment Study (LOTS) was published in 2010. The study was undertaken to evaluate the safety and efficacy of aglucosidase alfa in juvenile and adult patients with Pompe disease. LOTS was a randomized, double-blind, placebo-controlled study that enrolled 90 patients at eight primary sites in the United States and Europe. Participants received either aglucosidase alfa or a placebo every other week for 18 months. The average age of study participants was 44 years. The primary efficacy endpoints of the study sought to determine the effect of Myozyme on functional endurance as measured by the six-minute walk test and to determine the effect of aglucosidase alfa on pulmonary function as measured by percent predicted forced vital capacity.
The results showed that, at 78 weeks, patients treated with aglucosidase alfa increased their distance walked in six minutes by an average of approximately 25 meters as compared with the placebo group which declined by 3 meters (P=0.03). The placebo group did not show any improvement from baseline. The average baseline distance walked in six minutes in both groups was approximately 325 meters.
Percent predicted forced vital capacity in the group of patients treated with aglucosidase alfa increased by 1.2 percent at 78 weeks. In contrast, it declined by approximately 2.2 percent in the placebo group (P=0.006).
There is an emerging recognition of the role that diet and exercise can play in functionally limiting symptom progression. This is an area for further study, as there is not a clear consensus guideline, but rather a body of case study work that suggests that appropriate physical activity can be an effective tool in managing disease progression. In one such study, side-alternating vibration training was used 3 times per week for 15 weeks. The results showed that, at 15 weeks, the patient had a 116-meter (70%) improvement to their 6MWT, which is significant compared with the results from the aforementioned LOTS study.
Epidemiology
The disease affects approximately 1 in 13,000.
History
The disease is named after
Joannes Cassianus Pompe, who characterized it in 1932. Pompe described accumulation of glycogen in muscle tissue in some cases of a previously unknown disorder. This accumulation was difficult to explain as the enzymes involved in the usual metabolism of glucose and glycogen were all present and functioning.
The basis for the disease remained a puzzle until
Christian de Duve
Christian René Marie Joseph, Viscount de Duve (2 October 1917 – 4 May 2013) was a Nobel Prize-winning Belgian cytologist and biochemist. He made serendipitous discoveries of two cell organelles, peroxisome and lysosome, for which he shared ...
's discovery of lysosomes in 1955 for which he won the
Nobel Prize
The Nobel Prizes ( ; sv, Nobelpriset ; no, Nobelprisen ) are five separate prizes that, according to Alfred Nobel's will of 1895, are awarded to "those who, during the preceding year, have conferred the greatest benefit to humankind." Alfr ...
in 1974. His co-worker
Henri G. Hers realised in 1965 that the deficiency of a lysosomal enzyme (alpha glucosidase) for the breakdown of glycogen could explain the symptoms of Pompe disease. This discovery led to establishing the concept of lysosomal storage diseases, of which 49 have been described (to date).
Despite recognizing the basis for the disease, treatment proved difficult. Administration of the enzyme lead to its uptake by the liver and not the muscle cells where it is needed. In the early 1990s Dutch scientists
Arnold Reuser and
Ans van der Ploeg were able to show that using alpha-glucosidase containing phosphorylated mannose residues purified from bovine testes increased the enzyme's activity in normal mouse muscles.
Later in 1998,
Dr. Yuan-Tsong Chen and colleagues at Duke University, using the enzyme produced in Chinese Hamster Ovary cells demonstrated for the first time that the enzyme can clear the glycogen and improved the muscle function in Pompe disease quail. The results of the work at Duke were impressive with one treated bird recovering to the point of being able to fly again.
This was followed by production of clinical grade alpha-glucosidase in Chinese hamster ovary (CHO) cells and in the milk of transgenic rabbits.
This work eventually culminated in the start of clinical trials with the first clinical trial including 4 babies receiving enzyme from rabbit milk at
Erasmus MC Sophia Children's Hospital
Desiderius Erasmus Roterodamus (; ; English: Erasmus of Rotterdam or Erasmus;''Erasmus'' was his baptismal name, given after St. Erasmus of Formiae. ''Desiderius'' was an adopted additional name, which he used from 1496. The ''Roterodamus'' wa ...
and 3 babies receiving enzyme grown in CHO cells
[ at Duke University in 1999.
The currently approved Myozyme is manufactured by Genzyme Corp. in Cambridge, Massachusetts. Its development was a complex process. Genzyme first partnered with Pharming Group NV who had managed to produce acid alpha-glucosidase from the milk of transgenic rabbits. They also partnered with a second group based at Duke University using Chinese hamster ovary cells. In 2001, Genzyme acquired Novazyme which was also working on this enzyme. Genzyme also had its own product (Myozyme) grown in CHO cells under development. In November 2001, Genzyme chief executive ]Henri Termeer
Henri A. Termeer (February 28, 1946 – May 12, 2017) was a Dutch biotechnology executive and entrepreneur who is considered a pioneer in corporate strategy in the biotechnology industry for his tenure as CEO at Genzyme. Termeer created a busine ...
organised a systematic comparison of the various potential drugs in a mouse model of Pompe disease. It was found that the Duke enzyme was the most efficacious, followed by Myozyme. However, due to easier manufacture of Myozyme, work on the other products was discontinued.
Funding for research in this field was in part provided by the Muscular Dystrophy Association and the Acid Maltase Deficiency Association in the US, and by the Association of Glycogen Storage Disorders in the UK, as well as the International Pompe Association.
John Crowley became involved in the fund-raising efforts in 1998 after two of his children were diagnosed with Pompe. He joined the company Novazyme in 1999, which was working on enzyme replacement treatment for Pompe. Novazyme was sold to Genzyme in 2001 for over US$100 million. The 2010 film ''Extraordinary Measures
''Extraordinary Measures'' is a 2010 American medical drama film starring Brendan Fraser, Harrison Ford, and Keri Russell. It was the first film produced by CBS Films, the film division of CBS Corporation, who released the film on January 22, ...
'' is based on Crowley's search for a cure.
As of 2019, many biomedical companies are developing Gene therapy
Gene therapy is a medical field which focuses on the genetic modification of cells to produce a therapeutic effect or the treatment of disease by repairing or reconstructing defective genetic material. The first attempt at modifying human DN ...
in hopes of helping the body create alpha-glucosidase on its own.
In 2021, in utero infusions were provided to the fetus of an Ottawa, Ontario, mother who had had two previous children with Pompe disease. The medical team was a collaboration between an Ottawa group and a group at the University of California, San Francisco. The child, born in June 2021, is thriving as of November 2022.
References
External links
GeneReview/NIH/UW entry on Glycogen Storage Disease Type II (Pompe Disease)
Understanding Pompe Disease
nbsp;- US National Institute of Arthritis and Musculoskeletal and Skin Diseases
{{DEFAULTSORT:Glycogen Storage Disease Type Ii
Autosomal recessive disorders
Hepatology
Inborn errors of carbohydrate metabolism
Lysosomal storage diseases
Rare diseases