On the excess of mental retardation and/or congenital malformations in apparently balanced reciprocal translocations. A critical review of the Leuven data 1966-1991.
In this report we review 286 reciprocal translocations (rcpt) diagnosed in Leuven in the period 1966, mid 1991. They were selected from a total number of 82,000 patients karyotyped for constitutional reasons. Special attention is paid to: (1) the phenotypic effect of de novo reciprocal chromosomal rearrangements and (2) the incidence of mental retardation/congenital malformations (MR/CM) in familial rcpt. Important conclusions of this study were: 1) The high incidence of MR/CM in de novo rcpt, not only in patients with complex chromosomal rearrangements (greater than 80%) but also in patients with classical two breaks rcpt (greater than 60%). In contrast, the phenotypic effect of normal/mosaic rcpt seems to be minimal. 2) The overall incidence of MR/CM in carriers of familial balanced rcpt was 6.4%. Interestingly, the incidence of MR/CM problems in rcpt carriers from families detected because of reproductive failure was not increased (2.3%). However, the risk to find MR/CM in a rcpt carrier was much higher (12.8%) if he/she belonged to a family in which the rcpt was detected in an index patient with MR/CM.
Fryns
J P
JP
Center for Human Genetics, University of Leuven, Belgium.
Kleczkowska
A
A
Kubień
E
E
Van Den Berghe
H
H
D000013:Congenital Abnormalities / Q000175:diagnosis / Q000235:genetics*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008607:Intellectual Disability / Q000175:diagnosis / Q000235:genetics*; D007621:Karyotyping; D008297:Male; D010641:Phenotype; D014178:Translocation, Genetic / Q000235:genetics*