Chondrodysplasia

There are various types of chondrodysplasias, which affect growth of bone and cartilage.

• Achondroplasia is a relatively common cause of dwarfism, occurring in perhaps 1 in every 25,000 births. Most cases are due to a new mutation in the fibroblast growth factor receptor 3 gene FGFR3. Unlike some forms of dwarfism, achondroplastic dwarfism is not curable with growth hormone.

• Conradi-Hunermann syndrome, also known as X-linked dominant chondrodysplasia punctata, is caused by defects in the EPB gene. The following SNPs may be related to this or other types of chondrodysplasia:
  • rs28936073
  • rs743616 in the arylsulfatase A (ARSA) gene
  • rs28935474 in the arylsulfatase E (ARSE) gene on the X chromosome, also known as P578S, is recessive, according to OMIM 300180.0007
  • rs1065757 in the arylsulfatase B (ARSB) gene on chromosome 5 may be associated with chondrodysplasia punctata
  • rs2819590 in the SUMF1 gene may be related to chondrodysplasia punctata

• Jeune syndrome is an extremely rare but severe recessive disorder that causes death in infancy or early childhood. It is also known as asphyxiating thoracic dystrophy. Jeune syndrome is a ciliopathy caused by mutations in the IFT80 gene.

• Rhizomelic chondrodysplasia punctata type 1 (RCDP1) is caused by mutations in the PEX7 gene. The following SNP related to RCDP1 is tested by 23andMe:
  • i3002517, also known as L292X (risk genotype AA)

• Rhizomelic chondrodysplasia punctata type 2 (RCDP2) is associated with the following SNPs:
  • rs28939697
  • rs28939696
  • rs11558492 in the GNPAT gene
  • rs1129187 in the PEX8 gene may be related to RCDP