Rhizomelic chondrodysplasia punctata is a rare developmental brain disorder characterized by systemic shortening of the proximal bones (i.e.
rhizomelia
Rhizomelia refers to either a disproportion of the length of the proximal limb, such as the shortened limbs of achondroplasia, or some other disorder of the hip or shoulder.
According to Stedman's medical dictionary "rhizomelic" means "relating to ...
),
seizures
An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with l ...
, recurrent
respiratory tract infections
Respiratory tract infections (RTIs) are infectious diseases involving the respiratory tract. An infection of this type usually is further classified as an upper respiratory tract infection (URI or URTI) or a lower respiratory tract infection (LRI ...
and congenital
cataracts
A cataract is a cloudy area in the lens of the eye that leads to a decrease in vision. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry or double vision, halos around light, trouble w ...
. The affected individuals have low levels of
plasmalogens
Glycerophospholipids of biochemical relevance are divided into three subclasses based on the substitution present at the sn-1 position of the glycerol backbone: acyl, alkyl and alkenyl. Of these, the alkyl and alkenyl moiety in each case form an ...
.
[
]
Signs and symptoms
Rhizomelic chondrodysplasia punctata has the following symptoms:
* Bilateral shortening of the femur
The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...
* Post-natal growth problems (deficiency)
* Cataracts
A cataract is a cloudy area in the lens of the eye that leads to a decrease in vision. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry or double vision, halos around light, trouble w ...
* Intellectual disability
Intellectual disability (ID), also known as general learning disability in the United Kingdom and formerly mental retardation, Rosa's Law, Pub. L. 111-256124 Stat. 2643(2010). is a generalized neurodevelopmental disorder characterized by signif ...
* Possible seizures
An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with l ...
* Possible infections of respiratory tract
Genetics
This condition is a consequence of mutations in the PEX7
Peroxin-7 is a Receptor (biochemistry), receptor associated with Refsum's disease and rhizomelic chondrodysplasia punctata type 1.
See also
* Peroxin
External links
GeneReviews/NCBI/NIH/UW entry on Refsum Disease GeneReviews/NIH/NCBI/UW entry o ...
gene, the GNPAT gene (which is located on chromosome 1
Chromosome 1 is the designation for the largest human chromosome. Humans have two copies of chromosome 1, as they do with all of the autosomes, which are the non- sex chromosomes. Chromosome 1 spans about 249 million nucleotide base pairs, which ...
) or the AGPS gene. The condition is acquired in an autosomal
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 allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosom ...
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 ...
manner.
Pathophysiology
The mechanism of rhizomelic chondrodysplasia punctata in the case of ''type 1'' of this condition one finds that peroxisome objective is PEX7, in peroxisome assembly. There are 3 pathways that ''count on'' PEX7 and are:[
::::::* AGPS (''catalyzes plasmalogen biosynthesis'')
::::::*PhYH (''catalyzes catabolism of ]phytanic acid
Phytanic acid (or 3,7,11,15-tetramethyl hexadecanoic acid) is a branched chain fatty acid that humans can obtain through the consumption of dairy products, ruminant animal fats, and certain fish. Western diets are estimated to provide 50–100&nbs ...
'')
::::::* ACAA1 (''catalyzes beta-oxidation of VLCFA'' - straight)
Diagnosis
The diagnosis of rhizomelic chondrodysplasia punctata can be based on genetic testing as well as radiography
Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeu ...
results, plus a physical examination of the individual.
Types
* ''Type 1'' (RCDP1) is associated with PEX7
Peroxin-7 is a Receptor (biochemistry), receptor associated with Refsum's disease and rhizomelic chondrodysplasia punctata type 1.
See also
* Peroxin
External links
GeneReviews/NCBI/NIH/UW entry on Refsum Disease GeneReviews/NIH/NCBI/UW entry o ...
mutations; these are peroxisome biogenesis disorders where proper assembly of peroxisomes is impaired.
* ''Type 2'' (RCDP2) is associated with DHAPAT mutations
* ''Type 3'' (RCDP3) is associated with AGPS mutations
Treatment
Management of rhizomelic chondrodysplasia punctata can include physical therapy; additionally orthopedic
Orthopedic surgery or orthopedics ( alternatively spelt orthopaedics), is the branch of surgery concerned with conditions involving the musculoskeletal system. Orthopedic surgeons use both surgical and nonsurgical means to treat musculoskeletal ...
procedures improved function sometimes in affected people.[ However, the prognosis is poor in this condition.][
]
See also
* Plasmalogen
* Peroxisomal disorder
Peroxisomal disorders represent a class of medical conditions caused by defects in peroxisome functions. This may be due to defects in single enzymes important for peroxisome function or in peroxins, proteins encoded by ''PEX'' genes that are crit ...
References
Further reading
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External links
{{DEFAULTSORT:Rhizomelic Chondrodysplasia Punctata
Genodermatoses
Peroxisomal disorders