Mosaic trisomy 6 and maternal uniparental disomy 6 in a 23-week gestation fetus with atrioventricular septal defect.
Trisomy 6 is seen in early miscarriages in association with an intact, empty amniotic sac or as a pseudomosaic in amniotic fluid cultures. We report the finding of mosaic trisomy 6 in a 23-week-gestation pregnancy terminated because of intrauterine death. The post-mortem showed a well formed macerated male fetus with an atrioventricular septal defect and an exomphalos. By conventional cytogenetics, trisomy 6 was found in 12 out of 25 (48%) fibroblast colonies from fetal skin and 21 out of 32 (66%) colonies derived from amnion, while the remaining metaphases showed an apparently normal male karyotype. Molecular genetic studies on DNA from uncultured fetal skin and cord samples using polymorphic microsatellite repeat sequences showed no evidence of trisomy 6, but demonstrated that both chromosome 6 homologs were of maternal origin consistent with maternal uniparental disomy (UPD).
Wessex Regional Genetics Laboratory, Salisbury District Hospital, Salisbury, Wiltshire, United Kingdom. annette.cockwell@salisbury.nhs.uk
Annette E
AE
Cockwell
Samantha J
SJ
Baker
Margaret
M
Connarty
Isabella E
IE
Moore
John A
JA
Crolla
D002896:Chromosomes, Human, Pair 6 / Q000235:genetics*; D017809:Fatal Outcome; D005260:Female; D005313:Fetal Death; D005315:Fetal Diseases / Q000473:pathology; D005333:Fetus / Q000378:metabolism / Q000473:pathology; D005865:Gestational Age; D006343:Heart Septal Defects / Q000473:pathology*; D006344:Heart Septal Defects, Atrial / Q000473:pathology; D006345:Heart Septal Defects, Ventricular / Q000473:pathology; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male; D009030:Mosaicism; D009035:Mothers; D014314:Trisomy; D024182:Uniparental Disomy