Genetics for the clinician / C.A. Clarke.

  • Clarke, Cyril A. (Cyril Astley)
Date:
1964
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Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Genetics for the clinician / C.A. Clarke. Source: Wellcome Collection.

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    THE CHROMOSOMES OF MAN 29 important that the usefuhiess of dermatoglyphics should be more widely known. Holt (1963) has shown that abnormalities, though of a less striking kind, occur in patients with sex chromosome anomalies. On the other hand in patients with schizophrenia, epilepsy and paralytic polio¬ myelitis the patterns have not been found to vary significantly from controls. (Walker, 1963). It has long been known that mongols have a primitive type of leucocyte, the polymorphs having fewer lobes than normal. This immaturity may be associated with their increased liability to develop acute leukaemia, an association which only seems to have been recognized in recent years. A very interesting fmding is that some patients with chronic myeloid leukaemia possess an abnormal chromosome (probably No. 21) it being much smaller than normal possibly because of a deletion.* It seems, there¬ fore, that autosome 21 may have something to do with leucopoiesis and this fmding may ultimately be of considerable importance in under¬ standing the aetiology of leukaemia (Nowell and Hungerford, i960 and Baikie et al., i960). Some recent possible support for this comes from the work of Siebner and his colleagues (1963). These authors have shown that the Pelger-Huet anomaly (see glossary) of the leucocytes is sometimes associated with 46/47 mosaicism due to trisomy of (probably) chromo¬ some 20 (possibly 21). (b) The Trisomy-17 Syndrome Non-disjunction for chromosome No. 17 (possibly any of the 16-18 group) leading to trisomy as in mongolism, was first described by Edwards (i960) and the clinical picture is now reasonably weU-defmed, Affected infants have the following characteristics: mental retardation, a peculiar shaped skull (small mandible and prominent occiput), low-set and mal¬ formed ears, a receding chin and stubby fingers, tightly flexed, with the index commonly overlapping the medius. The feet are of rocker-bottom type. Ventricular septal defect is often present. GottHeb et al. (1962) report three cases of the syndrome and review the hterature, and Rosenfield et al. (1962) compare the syndrome with that of the 13-15 trisomy. In one of their 17-18 trisomy cases 'medial' arteriosclerosis was present and the authors conjecture that genes on chromosomes 17-18 may be cormected with the integrity of the internal elastic lamina. (c) Trisomy of the 13-15 Group This syndrome was first described by Patau et al. (i960) and again the infants are mentally retarded and have multiple abnormalities, and there * The Philadelphia or Ph' chromosome. 4