Recurrent trisomy 21 and uniparental disomy 21 in a family.
OBJECTIVE
A 32-year-old pregnant woman was referred to our genetic counselling because of recurrent trisomy 21 in the family. Analysis of amniotic fluid cell culture revealed karyotype 47,XY+21 of the fetus.


METHODS
Karyotyping and molecular analysis were undertaken in the fetal and parental samples to determine the origin of the extra chromosome 21.


RESULTS
Both parents had a normal blood karyotype. Microsatellite marker analysis showed maternal origin of the fetal extra chromosome 21. As the mother showed homozygosity for all investigated markers on chromosome 21, we also tested her family. We detected the same homozygosity in some family members which was consistent with isodisomy of the chromosome 21 caused by uniparental disomy (UPD).


CONCLUSIONS
Here we report on a family in which multiple aneuploid conceptions occurred with trisomy 21, and molecular analysis showed that the euploidy of the investigated healthy family members is due to UPD21. This observation stresses the importance of prenatal cytogenetic and molecular analysis in case of parental UPD.
Bán
Zoltán
Z
1st Department of Obstetrics and Gynaecology, Semmelweis University, Budapest, Hungary. banz@noi1.sote.hu
Nagy
Bálint
B
Papp
Csaba
C
Beke
Artúr
A
Tóth-Pál
Erno
E
Papp
Zoltán
Z
D000328:Adult; D000483:Alleles; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics*; D004314:Down Syndrome / Q000235:genetics*; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis / Q000235:genetics*; D006801:Humans; D008297:Male; D010375:Pedigree; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D024182:Uniparental Disomy / Q000235:genetics*