Association of transforming growth-factor alpha gene polymorphisms with nonsyndromic cleft palate only (CPO).

Genetic analysis and tissue-specific expression studies support a role for transforming growth-factor alpha (TGFA) in craniofacial development. Previous studies have confirmed an association of alleles for TGFA with nonsyndromic cleft lip with or without cleft palate (CL/P) in humans. We carried out a retrospective association study to determine whether specific allelic variants of the TGFA gene are also associated with cleft palate only (CPO). The PCR products from 12 overlapping sets of primers to the TGFA cDNA were examined by using single-strand conformational polymorphism analysis. Four DNA polymorphic sites for TGFA were identified in the 3' untranslated region of the TGFA gene. These variants, as well as previously identified RFLPs for TGFA, were characterized in case and control populations for CPO by using chi 2 analysis. A significant association between alleles of TGFA and CPO was identified which further supports a role for this gene as one of the genetic determinants of craniofacial development. Sequence analysis of the variants disclosed a cluster of three variable sites within 30 bp of each other in the 3' untranslated region previously associated with an antisense transcript. These studies extend the role for TGFA in craniofacial morphogenesis and support an interrelated mechanism underlying nonsyndromic forms of CL/P.