Chapter

Parental Autosomal Aneuploidy

R. J. McKinlay Gardner, Grant R. Sutherland and Lisa G. Shaffer

in Chromosome Abnormalities and Genetic Counseling

Fourth edition

Published on behalf of Oxford University Press

Published in print November 2011 | ISBN: 9780195375336
Published online October 2012 | e-ISBN: 9780199975174 | DOI: http://dx.doi.org/10.1093/med/9780195375336.003.0014

Series: Oxford Monographs on Medical Genetics

Parental Autosomal Aneuploidy

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A QUESTION OF REPRODUCTION is usually an academic matter in individuals with a cytogenetically detectable functional autosomal aneuploidy. But toward the milder end of the phenotypic range, social and emotional development may be such that forming a stable relationship is possible. Some who lack that degree of maturity may yet have a social freedom that opens the possibility of a sexual encounter. Either on their own behalf, or through the agency of parents or other carers (whose agenda may include sterilization), such people may present to the genetic clinic. Ethical issues raised in this context are aired in Chapter 1. With some of the deletions and duplications of lesser genetic imbalance revealed by molecular techniques, the phenotypic effects may be very mild, with social and intellectual functioning well within the normal range.

The mosaic state may on occasion be associated with an apparently normal phenotype, or at least very close to normal. Some of these persons will have been identified by their having had a child with the imbalance for which they themselves have a low-level mosaicism. Some present with infertility. The theoretical risk will depend upon the extent to which the gonad carries the aneuploid line.

In contrast, some structural imbalances are without discernible phenotypic effect. Deletion or duplication of a small segment of euchromatin, or the presence of a supernumerary marker chromosome (SMC), is occasionally recognized fortuitously in normal and fertile individuals.

Chapter.  5433 words.  Illustrated.

Subjects: Clinical Genetics

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