Isolation of a 370 kb YAC fragment spanning a translocation breakpoint at 3p14.1 associated with holoprosencephaly.

Holoprosencephaly (HPE) is a common developmental defect involving the brain and face. HPE is extremely heterogeneous, some cases being associated with structural anomalies of the short arm of chromosome 3. For a detailed characterization of a t(3;19)(p14.1;p13.1) breakpoint associated with HPE, we performed fluorescence in situ hybridization (FISH) analysis using yeast artificial chromosomes (YACs) mapped to the short arm of chromosome 3 from the Le Centre d'Etude du Polymorphisme Humain (CEPH) library. Three YACs mapped proximal, and one was located distal to the described breakpoint on chromosome 3. One of the chromosome 3 'Mega-YACs' spanned the translocation breakpoint. From this chimeric YAC we generated a site specific probe of about 370 kb by digestion of the YAC-DNA, which will be assessed for gene alterations that could underlie HPE in this patient.