Rhizomelic chondrodysplasia punctata
Template:Short description Template:Infobox medical condition (new) Rhizomelic chondrodysplasia punctata is a rare developmental brain disorder characterized by abnormally short arms and legs (rhizomelia), seizures, recurrent respiratory tract infections and congenital cataracts.
The cause is a genetic mutation that results in low levels of plasmalogens, which are a type of lipid found in cell membranes throughout the body, but whose function is not known.[1]
Signs and symptoms
Rhizomelic chondrodysplasia punctata has the following symptoms:[2][3]
- Bilateral shortening of the femur, resulting in short legs
- Post-natal growth problems (deficiency)
- Cataracts
- Intellectual disability
- Possible seizures
- Possible infections of respiratory tract
Genetics
This condition is a consequence of mutations in the PEX7 gene, the GNPAT gene (which is located on chromosome 1) or the AGPS gene. The condition is acquired in an autosomal recessive manner.[1]
Pathophysiology
The mechanism of rhizomelic chondrodysplasia punctata in the case of type 1 of this condition involves a defect in PEX7, whose product is involved in peroxisome assembly. There are 3 pathways that depend on peroxisomal biogenesis factor 7 activities, including:[2][4]Script error: No such module "Unsubst".
- AGPS (catalyzes plasmalogen biosynthesis)
- PhYH (catalyzes catabolism of phytanic acid)
- ACAA1 (catalyzes beta-oxidation of VLCFA - straight)
Diagnosis
The diagnosis of rhizomelic chondrodysplasia punctata can be based on genetic testing[5] as well as radiography results, plus a physical examination of the individual.[6]
Types
- Type 1 (RCDP1) is associated with PEX7 mutations; these are peroxisome biogenesis disorders where proper assembly of peroxisomes is impaired.[2]
- Type 2 (RCDP2) is associated with DHAPAT mutations.[7]
- Type 3 (RCDP3) is associated with AGPS mutations.[8]
Treatment
Management of rhizomelic chondrodysplasia punctata can include physical therapy; additionally orthopedic procedures improved function sometimes in affected people.[2]
Prognosis
The prognosis is poor in this condition,[6] and most children die before the age of 10.[2] However, some survive to adulthood, especially if they have a non-classical (mild) form of RCDP.[2]
Children with classical, or severe, RCDP1 have severe developmental disabilities. Most of them achieve early developmental skills, such as smiling, but they will not develop skills expected from a baby older than six months (such as feeding themselves or walking).[2] By contrast, children with non-classical mild RCDP1 often learn to walk and talk.[2]
See also
References
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- ↑ Online Mendelian Inheritance in Man (OMIM): Rhizomelic Chondrodysplasia Punctata, Type 2; RCDP2 - 222765
- ↑ Online Mendelian Inheritance in Man (OMIM): Rhizomelic Chondrodysplasia Punctata, Type 3; RCDP3 - 600121
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Further reading
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External links
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