Lack of linkage of apparently dominant cleft lip (palate) to two candidate chromosomal regions.

Two regions were chosen for linkage studies to cleft lip with or without cleft palate (CL[P]) because they are break points of a balanced translocation in a patient with severe bilateral facial clefting. We used dinucleotide repeats to test chromosomal regions 1q21 and 22q11.2 for such linkage. We studied three families with apparently dominantly inherited CL(P). Families #1 and #2 are local Caucasian families that have not been previously reported; family #3 is a Belgian family that has been previously published [DePaepe, 1989]. Significant evidence against close linkage of the dinucleotide repeats (D1S104, D22S156, D22S264) with CL(P) using a dominant model was obtained. Three other candidate regions were tested (2q37,4q31, and 8p) with the dinucleotide repeats PAX3, D4S175, and LPL respectively. The LOD scores generated at these three loci are not statistically significant for demonstrating negative linkage at these regions. However, they may be used with other informative families in the future, since LOD scores for the same model of inheritance may be added together. Negative or neutral LOD scores were generated at all informative loci using an autosomal dominant model with decreased penetrance.