Refined genetic and physical mapping of BPES type II.

ABSTRACT

BPES is a genetic disorder including blepharophimosis, ptosis of the eyelids, epicanthus inversus and telecanthus. Type I is associated with female infertility, whereas type II presents without other symptoms. Both types I and II occur sporadically or are inherited as an autosomal dominant trait. We present a molecular genetic and cytogenetic study in a large four-generation Belgian family with BPES type II. Karyotype analysis on high-resolution banded chromosomes yielded normal results. Fluorescence in situ hybridization (FISH) with cosmid probes spanning 3q22-q24 revealed normal hybridization patterns. Sixteen polymorphic CA repeats encompassing region 3q13-q25 were analysed. Linkage analysis in this large four-generation family provides conclusive evidence for the presence of a BPES gene in this region. Two-point lod scores greater than 3.0 between the disease and the following markers were seen D3S1589 (4.67), D3S1292 (3.52), D3S1290 (3.59) and D3S1549 (3.65). By FISH, D3S1290, D3S1292 and D3S1549 were assigned to chromosome 3q23 using YACs positive for these markers.