DOWN-SYNDROME WITH BIPARENTAL INHERITANCE OF DER(14Q21Q) AND MATERNALLY DERIVED TRISOMY-21 - CONFIRMATION BY FLUORESCENT IN-SITU HYBRIDIZATION AND MICROSATELLITE POLYMORPHISM ANALYSIS

Individuals with translocation Down syndrome (DS) often inherit the re arranged chromosome from a carrier parent, DS due to inheritance of on e Robertsonian or derivative (14q21q) from one parent and a second der (14q21q) in addition to a free chromosome 21 from the other parent are rarely documented in liveborn infants, Presented here is such a propo situs with DS and with a unique karyotype 45,XY,der(14;21) +21mat, Usi ng conventional chromosome heteromorphisms, fluorescent in situ hybrid ization (FISH), and microsatellite polymorphism analyses, we establish ed the biparental origin of the 2 der(14q21q) and the maternal origin of the extra chromosome 21 in the patient, A combination of both cytog enetic and molecular genetic techniques also enabled us to show that t he 2 der(14q21q) were not identical by descent and hence the parents w ere nonconsanguineous, It has been a well-established fact that mother s with Robertsonian translocations have higher risk for nondisjunction than do carrier fathers, Our case, wherein the nondisjunctional event occurred in the mother, even though both parents are carriers of a 14 ;21 Robertsonian translocation, is yet another example of this. (C) 19 97 Wiley-Lies, Inc.