A jumping Robertsonian translocation: a molecular and cytogenetic study.
We report a patient with mosaicism for two different Robertsonian translocations, both involving chromosome 21. She carries an unbalanced cell line with an i(21q) and a balanced cell line with a rob(21q22q). She is phenotypically normal but has two children who inherited the i(21q) and have Down syndrome. We demonstrate that both abnormal chromosomes are dicentric and that the proband's 21/21 rearrangement is an isochromosome formed from a maternally derived chromosome 21. We propose a model in which the i(21q) is the progenitor rearrangement in the proband, which subsequently participated in a nonreciprocal rearrangement characteristic of a jumping translocation. In addition, we review other cases of constitutional mosaicism involving jumping translocations.
Gross
S J
SJ
Department of Obstetrics and Gynecology, University of Tennessee, Memphis 38163, USA.
Tharapel
A T
AT
Phillips
O P
OP
Shulman
L P
LP
Pivnick
E K
EK
Park
V M
VM
D000328:Adult; D002648:Child; D002891:Chromosomes, Human, Pair 21; D002892:Chromosomes, Human, Pair 22; D004314:Down Syndrome / Q000235:genetics; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007223:Infant; D007621:Karyotyping; D008297:Male; D009030:Mosaicism; D010375:Pedigree; D014178:Translocation, Genetic