Linkage analyses performed in this family support the view that neither the RET locus (candidate for familial dominant Hirschsprung disease) nor the HuP2 locus (candidate for Waardenburg syndrome type I) are involved in the disease phenotype.
The RET and the Pax 3 genes have recently been shown to account for autosomal dominant Hirschsprung's disease (HSCR) and Waardenburg syndrome type 1 (WS1) respectively, which led us to consider them as candidate genes in the WS/HSCR association.
We have examined the following possible linked markers in 69 relatives in this family: the c-ret gene (HSCR); the human PAX3 gene (HuP2) on chromosome 2q (WS1) and placental alkaline phosphatase (ALPP) on chromosome 2q (linked to WS1); argininosuccinate synthetase (ASS) on chromosome 9q, close to ABO blood groups which have shown weak linkage to WS; and the beta 1 GABA receptor gene (GABARB1) on chromosome 4q13-11, close to c-kit, deletions of which cause piebaldism.