Medicine:Rhizomelic chondrodysplasia punctata

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Short description: Recessive genetic condition
Rhizomelic chondrodysplasia punctata
Plasmologen.svg
Low levels of plasmalogens is a characteristic of rhizomelic chondrodysplasia punctata.
SymptomsAlopecia, flat face[1]
CausesPEX7 gene, GNPAT gene and AGPS gene mutations[2]
Diagnostic methodClinical and radiologic finding[3]
TreatmentPhysical therapy[4]

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.[2]

Signs and symptoms

Rhizomelic chondrodysplasia punctata has the following symptoms:[4][1]

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.[2]

Pathophysiology

ACAA1

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:[4][5][verification needed]

  • AGPS (catalyzes plasmalogen biosynthesis)
  • PhYH (catalyzes catabolism of phytanic acid)
  • ACAA1 (catalyzes beta-oxidation of VLCFA - straight)

Diagnosis

Peroxisome (this condition affects the peroxisome, causing peroxisome biogenesis disorders.)

The diagnosis of rhizomelic chondrodysplasia punctata can be based on genetic testing[6] as well as radiography results, plus a physical examination of the individual.[3]

Types

  • Type 1 (RCDP1) is associated with PEX7 mutations; these are peroxisome biogenesis disorders where proper assembly of peroxisomes is impaired.[4]
  • 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.[4]

Prognosis

The prognosis is poor in this condition,[3] and most children die before the age of 10.[4] However, some survive to adulthood, especially if they have a non-classical (mild) form of RCDP.[4]

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).[4] By contrast, children with non-classical mild RCDP1 often learn to walk and talk.[4]

See also

References

Further reading

External links

Classification
External resources