<unk>  is commonly caused by chromosomal abnormalities in or around the gene SOX9 on the long arm of chromosome 17, specifically at position 17q24, generally spontaneously arising or de novo mutations. Also, numerous single nucleotide variants been identified involving the SOX9 gene that cause some form of<unk> . The SOX9 gene codes for a protein transcription factor which, when expressed at the embryonic stage, plays an important role in determining sexual characteristics and greatly influences skeletal development. When the SRY gene of the Y chromosome is expressed in human embryos, a cascade of gene interactions controlled by SOX9 begins and ultimately leads to male gender.. Any mutation within the coding region of SOX9 can cause<unk>  and 75% of the reported mutations lead to sex reversal. Four major classes of heterozygous SOX9 mutations can cause<unk> : amino acid substitutions in the HMG-box, truncations or frameshifts that alter the C-terminal end, mutations at the splice junction, and chromosomal translocations. Additionally, mutations upstream from SOX9 can also cause<unk> . Several researchers have reported cis-acting control elements upstream of SOX9. Translocation breakpoints scattered over 1Mb proximal to SOX9 indicate the presence of an extended control region. The lack of correlation between specific genetic mutations and observed phenotype, particularly with regard to sex reversal, give clear evidence of the variable expressivity of the disease. Milder forms of the disease, seen in those who live beyond the neonatal period and those with ACD, may perhaps be attributable to somatic mosaicism—particularly for those with mutations within the SOX9 coding region. Chromosomal aberrations in the upstream control regions or residual activity of the mutant SOX9 protein could also be responsible for the milder forms of the disease. Long-term survivors of<unk>  are significantly more likely to have translocation and inversion mutations upstream of SOX9 rather than mutations in the SOX9 coding region itself.
Campomelic dysplasia
Acromesomelic dysplasia
Langer mesomelic dysplasia
Hereditary coproporphyria
Mondini dysplasia
Imperforate anus
Mandibuloacral dysplasia
Thanatophoric dysplasia