Journal of Research in Medical Sciences1735-199512220070611Uniparental disomy resulting from heterozygous Robertsonian translocation (13q14q) in both parents100103ENMir DavoodOmraniDepartment of Genetics, Uremia University of Medical Sciences. davood_omrani@umsu.ac.irSorayaSaleh Gargari200611282007020920070131Uniparental disomy (UPD) is a situation in which both members of a chromosome pair are inherited from one parent. This study has been conducted on a family with a five year-old healthy girl and a mentally retarded boy. The parents were first cousins and they both had Robertsonian translocation between their long arm of chromosome 13 and 14 [45, XY t (13q14q)]. Their affected son had a similar karyotype. Their daughter’s karyotype revealed the presence of a homozygous Robertsonian 13/14 translocation 44, XX t (13q14), t(13q14q). According to the clinical findings it is possible to conclude that the affected boy suffers from UPD.KEY WORDS: Robertsonian translocation, uniparental disomy, chromosome 14.