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

* 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

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.

References

External links

{{DEFAULTSORT:Rhizomelic Chondrodysplasia Punctata Genodermatoses Peroxisomal disorders