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Linkage studies of x-linked cleft palate and ankyloglossia in a British Columbia native kindred Gorski, Sharon M.


Human craniofacial malformations are a class of common congenital anomalies. Their etiology is heterogeneous and often poorly understood. To elucidate the nature of craniofacial defects at the molecular level, one approach is to study the exceptional examples of malformations which segregate in families as single gene disorders. This study employs such an approach: it is directed toward the isolation of a locus responsible for cleft palate and ankyloglossia which segregate as a single X-linked trait (CPX) in a British Columbia (B.C.) Native kindred. The original description (Lowry 1970) of the clefting defect in the B.C. kindred included submucous cleft palate and bifid or absent uvula. Sixty-three of the B.C. family members were clinically reevaluated and it was observed that some of the affected males and carrier females also present with ankyloglossia (tongue-tie). Ankyloglossia previously has been associated with X-linked cleft palate in an Icelandic kindred in which a locus responsible for cleft palate was provisionally assigned to the Xq21.3-q22 region (Moore et al. 1987; Ivens et al. 1988). This thesis describes linkage analyses in the B.C. kindred which were initiated with DNA markers from the Xq21-q22 region and were later expanded to include markers from the Xq13 region. No recombination was observed between CPX and the DNA markers DXS447 (peak lod score [Zmax ] = 9.38), DXS72 (Zmax = 7.74; Gorski et al. 1992) and DXS326 (Zmax = 2.27). A new polymorphic DNA marker, X850A/L-7, was generated and mapped to the Xq21.1-q21.3 region. X850A/L-7 was found to be partially informative in the B.C. family and also nonrecombinant with respect to CPX (Zmax = 1.91). Recombination was observed between CPX and PGK1 (Zmax = 7.63 at recombination fraction [θ̂̂̂] = 0.03) and between CPX and DXYS1 (Zmax = 5.59 at θ =0.04). These results localize B.C. CPX between PGK1 and DXYS1 in the Xq13.3-q21.31 region.

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