Isolation ofa new markerandconserved sequences close totheDiGeorge syndrome markerHP500(D22S134)

Endfragmentcloning fromaYAC atthe D22S134locusallowedtheisolation ofa new probeHD7k.Thismarkerdetects hemizygosity intwopatients previously showntobedizygous forD22S134. This positions thedistal deletion breakpoint in thesepatients tothesequences withinthe YAC,andconfirmsthatHD7k isproximal toD22S134. Ina searchforcoding sequenceswithintheregioncommonly deleted inDGS we haveidentified aconservedsequence atD22S134. Althoughno cDNAs haveyetbeenisolated, genomic sequencing showsa shortopenreading framewithweaksimilarity tocollagen proteins. (JMedGenet 1993;30:818-21)