title: Identification of susceptibility loci for nonsyndromic cleft lip with or without cleft palate in a two stage genome scan of affected sib-pairs.
abstract: Nonsyndromic cleft lip with or without cleft palate (CL/P) is a complex disorder of multigenic origin involving between two and ten loci. Linkage and association studies of CL/P have implicated a number of candidate genes and regions but have often proved difficult to replicate. Here, we report the findings from a two-stage genome-wide scan of 92 affected sib-pairs to identify susceptibility loci to CL/P. An initial set of 400 microsatellite markers was used, with an average spacing of 10 cM throughout the genome. Eleven regions on eight chromosomes were found to have a P-value smaller than 0.05. These eight chromosomes were then further mapped with a second set of markers to increase the average map density to 5 cM. In seven out of eleven areas densely mapped, significance was markedly increased by decreasing the marker interval. Excessive allele sharing was found at 1p (NPL=2.35, P=0.009, MLS=1.51), 2p (NPL=1.77, P= 0.04, MLS=0.66), 6p (NPL=2.35, P=0.009, MLS=1.34), 8q (NPL=2.15, P=0.015, MLS= 1.51) 11 cen (NPL=2.70, P=0.003, MLS=2.10), 12q (NPL=2.08, P=0.02, MLS= 1.5), 16p (NPL=2.1, P=0.018, MLS=0.97) and Xcen-q (NPL=2.40, P=0.008, MLS=2.68). Although none reached the level required for significant susceptibility loci, two of these areas have previously been implicated in CL/P, viz. 2p13, an area harbouring the TGFA gene, and 6p23-24. We also demonstrate highly suggestive linkage to a susceptibility locus for nonsyndromic clefting on the X chromosome. Further studies are currently underway to replicate these findings in a larger cohort of affected sib-pairs.
authors.affiliation: Clinical and Molecular Genetics Unit, Institute of Child Health UCL, London, UK. n.prescott@ich.ucl.ac.uk
authors.forename: N J
authors.initials: NJ
authors.lastname: Prescott
authors.forename: M M
authors.initials: MM
authors.lastname: Lees
authors.forename: R M
authors.initials: RM
authors.lastname: Winter
authors.forename: S
authors.initials: S
authors.lastname: Malcolm
mesh_terms: D002874:Chromosome Mapping; D002971:Cleft Lip / Q000235:genetics*; D002972:Cleft Palate / Q000235:genetics*; D005260:Female; D008040:Genetic Linkage; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005820:Genetic Testing; D006801:Humans; D008126:Lod Score; D008297:Male; D018895:Microsatellite Repeats; D009679:Nuclear Family; D016211:Transforming Growth Factor alpha / Q000235:genetics; D006113:United Kingdom
chemical_list: D016211:Transforming Growth Factor alpha