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A case of maternal uniparental disomy of chromosome 9 diagnosed prenatally and the related problem of residual trisomy
Author(s) -
Slater Howard R.,
Ralph Adrianne,
Daniel Art,
Worthington Sharron,
Roberts Cynthia
Publication year - 2000
Publication title -
prenatal diagnosis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.956
H-Index - 97
eISSN - 1097-0223
pISSN - 0197-3851
DOI - 10.1002/1097-0223(200011)20:11<930::aid-pd955>3.0.co;2-e
Subject(s) - uniparental disomy , trisomy , chorionic villus sampling , amniocentesis , meiosis ii , prenatal diagnosis , karyotype , chromosome , biology , aneuploidy , fetus , genetics , pregnancy , obstetrics , medicine , gene
Non‐mosaic trisomy 9 was found in a chorionic villus (CV) sample taken from a 43‐year‐old woman referred for prenatal chromosome analysis due to advanced maternal age. Follow‐up amniocentesis revealed level 2 mosaicism for trisomy 9. Trisomy 9 was not detected at fetal blood sampling. Molecular analysis of fetal (amniocyte) DNA showed maternal uniparental heterodisomy (UPD) for chromosome 9. Two crossovers resulted in a region of isodisomy in the distal long arm. Trisomy rescue of a meiosis 1 segregation error seems to have been responsible for the uniparental disomy of chromosome 9. The pregnancy continued and neonatal blood testing showed a mosaic trisomy 9 karyotype, i.e. 4/50 cells analysed. Clinical postnatal follow‐up for a period of 1 year has documented only minor facial dysmorphism and skeletal abnormalities. Development appears unremarkable. This case is the second report of maternal uniparental disomy for chromosome 9 detected prenatally and is the first case followed up post‐term. This report highlights the difficulty of making informed prognostic assessments in such cases despite extensive laboratory investigation. Copyright © 2000 John Wiley & Sons, Ltd.