Acta Medica OkayamaVolume 43, Issue 2 1989 Article 5

APRIL 1989

A cytogenetic study of nonpolymalformedpatients with mental retardation of clinically

undefined etiology: application of a highresolution banding technique.

Kiyoshi Kikkawa∗ Kouji Narahara†

Hiroshi Kimoto‡

∗Okayama University,†Okayama University,‡Okayama University,

Copyright c©1999 OKAYAMA UNIVERSITY MEDICAL SCHOOL. All rights reserved.

A cytogenetic study of nonpolymalformedpatients with mental retardation of clinically

undefined etiology: application of a highresolution banding technique.∗

Kiyoshi Kikkawa, Kouji Narahara, and Hiroshi Kimoto

Abstract

We performed a cytogenetic study on 140 nonpolymalformed patients with mental retarda-tion of clinically undefined origin, using a high resolution banding technique, to determine howmuch chromosome abnormalities contribute to the etiology of this condition. A total of 15 patients(10.7%) were found to have autosomal or sex chromosomal abnormalities. Autosomal abnormal-ities included partial monosomy (5 cases), reciprocal translocation (one case), 13/14 robertsoniantranslocation (3 cases), unbalanced translocation (one case), inverted duplication of 15q (one case)and mosaic trisomy 21 (one case). Sex chromosomal abnormalities comprised structural rear-rangement of the short arm of the X chromosome (one case) and 47, XXY in a pure or mosaicform (two cases). It should be noted that four out of the 5 cases of partial monosomy had subtleinterstitial deletions, which might have been unidentified by the conventional G-banding methodalone. In one case of the robertsonian translocation 46,XY,t(13;14)/45,XY,t(13;14), a small dele-tion was thought to have occurred in the cells with a chromosome number of 45. Comparison ofclinical features of the 15 chromosomally abnormal patients with those of patients with normalkaryotypes did not show any clinical parameter indicative of chromosome imbalance. These re-sults suggest that a subtle chromosomal deletion is specific to mental retardation associated withfew malformations. We believe that diagnostic evaluation of mentally retarded patients, even ifnonmalformed, should include chromosome analysis using a high resolution banding technique.

KEYWORDS: chromosomes, high resolution banding technique, subtle interstitial deletion, men-tal retardation

∗PMID: 2728904 [PubMed - indexed for MEDLINE]Copyright (C) OKAYAMA UNIVERSITY MEDICAL SCHOOL

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Kikkawa et al.: A cytogenetic study of nonpolymalformed patients with mental

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Acta Medica Okayama, Vol. 43 [1989], Iss. 2, Art. 5

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Kikkawa et al.: A cytogenetic study of nonpolymalformed patients with mental

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Acta Medica Okayama, Vol. 43 [1989], Iss. 2, Art. 5

http://escholarship.lib.okayama-u.ac.jp/amo/vol43/iss2/5

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Kikkawa et al.: A cytogenetic study of nonpolymalformed patients with mental

Produced by The Berkeley Electronic Press, 1989

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Acta Medica Okayama, Vol. 43 [1989], Iss. 2, Art. 5

http://escholarship.lib.okayama-u.ac.jp/amo/vol43/iss2/5

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Kikkawa et al.: A cytogenetic study of nonpolymalformed patients with mental

Produced by The Berkeley Electronic Press, 1989

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Acta Medica Okayama, Vol. 43 [1989], Iss. 2, Art. 5

http://escholarship.lib.okayama-u.ac.jp/amo/vol43/iss2/5

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Kikkawa et al.: A cytogenetic study of nonpolymalformed patients with mental

Produced by The Berkeley Electronic Press, 1989

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Acta Medica Okayama, Vol. 43 [1989], Iss. 2, Art. 5

http://escholarship.lib.okayama-u.ac.jp/amo/vol43/iss2/5