Since we observed a decrease in SOX9 expression in sporadic CGHT patient keratinocytes, consistent with our previous findings in an autosomal dominant CGHT case [4] and considering the known role of SOX9 in hair follicle stem cells [30], [31], it is likely that the excessive hair overgrowth phenotype observed in sporadic CGHT may be the result of reduced levels of both ABCA5 and SOX9 transcripts. This evidence concerns the gene ABCA5 and gingival fibromatosis-hypertrichosis syndrome.