The rhizomelic chondrodysplasia is a form chondrodysplasia punctata of a group of diseases whose common characteristic calcifications around the joints from birth.
Rhizomelic prevalence rate is estimated at 1 in 100,000. This disease is inherited in an autosomal recessive manner and is caused by a defective peroxisome metabolism. Most affected patients have mutations in the gene PEX7 (6q21-q22.2), which encodes for peroxisomal type 2 receptor, it plays an important role in protein transport in the peroxisome. Other cases are due to mutations in the GNPAT gene (1q42), encoding a dihydroxyacetone phosphate acyltransferase or AGPS gene (2q31), encoding a peroxisomal alkyl dihydroxyacetone phosphate synthase.
The rhizomelic chondrodysplasia presents: short femur and humerus, vertebral disorders, cataract, cutaneous lesions and severe intellectual deficit.
Diagnosis is based on clinical and radiological signs and can be confirmed by molecular analysis. The main differential diagnosis is Zellweger syndrome. Prenatal diagnosis is possible when the causative mutation of the disease has been previously identified in the family.
There is no specific treatment for the enzyme deficiency. The rhizomelic condrodisplasia has a grave prognosis, usually with death during first decade of life (mainly because of respiratory complications).