Search for somatic 22q11.2 deletions in patients with conotruncal heart defects.
A wide range of clinical variability in patients with 22q11.2 deletions has been demonstrated in numerous studies. Nevertheless, it is still an open question if major genetic factors contribute to clinical expression. Therefore one aim of this study was to investigate, if patients with 22q11.2 deletion and conotruncal heart defects show a "second hit" somatic 22q11.2 deletion in tissue from the conotruncus, heart vessels or thymus. The second aim was to analyse patients with conotruncal heart defects without 22q11.2 deletion in blood cells for somatic deletion mosaicism. We were able to study tissue samples from heart surgery from 23 patients, 9 of whom had 22q11 deletions by FISH analysis on metaphase spreads from peripheral lymphocytes. Analysis of 18 polymorphic markers from the 22q11.2 region in DNA prepared from thymus and/or heart vessels and/or conotruncus tissue and peripheral lymphocytes in each patient did not show any allelic loss. Thus somatic 22q11.2 deletions apparently do not play a major role in conotruncal heart defects in patients with or without germ line 22q11.2 deletion.
Rauch
Anita
A
Institute of Human Genetics, Friedrich-Alexander University, Erlangen-Nuremberg, Germany. arauch@humgenet.uni-erlangen.de
Hofbeck
Michael
M
Cesnjevar
Robert
R
Koch
Andreas
A
Rauch
Ralf
R
Buheitel
Gernot
G
Singer
Helmut
H
Weyand
Michael
M
D002648:Child; D002872:Chromosome Deletion; D002874:Chromosome Mapping; D002892:Chromosomes, Human, Pair 22 / Q000235:genetics*; D005820:Genetic Testing; D018095:Germ-Line Mutation; D006330:Heart Defects, Congenital / Q000175:diagnosis / Q000235:genetics*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D018895:Microsatellite Repeats