A partial D-trisomy-normal mosaic female.

Abstract

During a chromosome survey of mentally retarded children with epicanthic folds, an 8-yearold girl was found to have an extra medium-sized, satellited, acrocentric chromosome in a percentage of cells in peripheral blood, bone marrow, and skin. However, she did not show any of the clinical abnormalities associated with D-trisomy (Patau et al, 1960). Therefore clinical and cytogenetic studies together with special investigations performed on this child are described.Case Report The proposita J.M. was born on 21 June 1960 by a breech delivery, to a 38-year-old mother and a 46-yearold father, who were unrelated. Her birth weight was 3040 g. Apart from an early threatened miscarriage treated with progesterone, the pregnancy was normal.Clinical examination of the proposita at the age of 8 years showed profound mental retardation, epicanthic folds, and a mild degree of microcephaly (Fig. 1). On psychological testing she was found to be hyperactive and to have an IQ below 20. Radiology of the skull was normal. The Guthrie test for phenylketonuria and urine amino-acid chromatography were negative. The red cell phosphohexokinase level was within the normal range, ie, 16-9-24-6 micromoles ofsubstrate/min/3-2 g Hb (Baikie et al, 1965). Abnormal projections from the nuclei of the polymorphonuclear leucocytes as described in D-trisomy by Huehns, Lutzner, and Hecht (1964b) were not present.Fetal haemoglobin, estimated when the proposita was aged 7 years, was found to be 9 3O% by the alkali denaturation method (Singer, Chernoff, and Singer, 1951) and, at the same time using the acid-elution technique of Kleihauer, Braun, and Betke (1957), 55% of the erythrocytes were shown to contain some fetal haemoglobin. However, subsequent tests by alkali denaturation in the same laboratory over a period of 3 years showed wide variation even in replicates. The measurement had a

Partial trisomy 15 in a male with severe psychomotor retardation (48,XY,+15q−, +mar(15))

“…The discrepancy between the two cases might originate from the different distribution of the abnormal cell line in various tissues, determining the phenotypic effect. In the two above mentioned cases [15,16] the extra chromosome resembles the 15q -found in our propositus rather than the M chromosome found in the father. Therefore, we tend to ascribe his normal phenotype to the heterochromatic nature of M.…”

“…Thus, the very same chromosome abnormality in mosaic form did not cause any of the disturbances caused when it was present in all the cells. However, Webb et a1 [16] described an 8-year-old girl who was a mosaic for a Dq -(most probably 15q-) trisomy and mentally retarded. The discrepancy between the two cases might originate from the different distribution of the abnormal cell line in various tissues, determining the phenotypic effect.…”

“…There was a slight generalized aminoaciduria; IVP was normal. At age 16 he is severely mentally retarded, does not speak, and is currently institutionalized.…”

46,XX/47XX, + 14 mosaicism in a liveborn infant.

“…Thus, some 'atypical' cases of Case reports 'trisomy 13 syndrome' (e.g. Snodgrass et al, 1966;Neu et al, 1971 ;Webb et al, 1971) conceivably could represent cases of trisomy 14. Fourth, trisomy 14 may produce so few phenotypic abnormalities that affected individuals are not necessarily brought for genetic consultation.…”

“…Chromosomal banding studies were not performed in either case. The chromosomal complements were (a) 47,XX,+D (From Neu et al, 1971), (b) 46,XX/47,XX,+D (Webb et al, 1971).…”