Chapter

Autosomal ring chromosomes

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/9780195375336.003.0011

Series: Oxford Monographs on Medical Genetics

Autosomal ring chromosomes

Show Summary Details

Preview

RING CHROMOSOMES ARE UNCOMMON, and it is even more uncommon for a person with a ring (or someone on their behalf) to seek genetic advice about reproductive possibilities. The typical physical phenotype comprises major dysmorphogenesis and mental retardation, and procreation is not usually a relevant issue. But exceptions exist. Remarkably, some persons with a ring chromosome seem to be of entirely normal phenotype. Only mild mental retardation, or short stature with minor dysmorphism, characterizes some other cases. The ring 20 has a unique association with epilepsy. It is these categories of normal or mildly abnormal phenotype — in other words, of possible reproductive potential — we particularly consider in this chapter, although at the outset we can state that only a few examples of parental transmission of ring chromosomes are known. About 99 % of rings arise sporadically .

Chapter.  6328 words.  Illustrated.

Subjects: Clinical Genetics

Full text: subscription required

How to subscribe Recommend to my Librarian

Buy this work at Oxford University Press »

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.