Maternal insertion of 18q11.2-q12.2 in 18p11.3 of the same chromosome analysed by microdissection and multicolour banding (MCB).
OBJECTIVE
Different aberrations in one chromosome 18 were prenatally detected during each of three different pregnancies of a healthy woman. Routine cytogenetic analysis revealed a morphologically altered maternal chromosome 18 as well. The purpose of the current study was to characterize these cytogenetic changes in detail and thus to clarify the reason for the recurrent appearance of morphologically altered chromosomes 18 in this family.


METHODS
As GTG banding did not allow resolution of the kind of aberrations present in these four cases, the following molecular cytogenetic approaches were used: microdissection combined with reverse painting and multicolour banding (MCB) analysis using a chromosome 18 specific probe set.


RESULTS
Molecular cytogenetic approaches revealed that fetus 1 had a derivative chromosome del(18)(q11.2q12.2), fetus 2 and the mother had the identical derivative chromosomes ins(18)(pterp11.32::q12.2q11.2::p11.32q11.2::q12.3qter) and fetus 3 had a dup(11.2q12.2).


CONCLUSIONS
Partial monosomy in fetus 1 and partial trisomy in fetus 3 can be explained by crossing over events during maternal meiosis.
Starke
H
H
Institute of Human Genetics and Anthropology, Kollegiengasse 10, D-07740 Jena, Germany.
Senger
G
G
Kossakiewicz
M
M
Tittelbach
H
H
Rau
D
D
Rubtsov
N
N
Trifonov
V
V
Heller
A
A
Hartmann
I
I
Claussen
U
U
Liehr
T
T
D000328:Adult; D000653:Amniotic Fluid / Q000166:cytology; D002871:Chromosome Banding; D002887:Chromosomes, Human, Pair 18; D020732:Cytogenetic Analysis; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D016254:Mutagenesis, Insertional; D011247:Pregnancy; D011296:Prenatal Diagnosis