Trisomy 21 in a child due to paternal nondisjunction as determined by RFA technique

Verma, Ram S.; Dosik, Harvey

doi:10.1007/bf01871378

Cited by 8 publications

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“…The current studies of families with Down syndrome suggest that about one-third of all cases of trisomy 21 are due to paternal nondisjunction (13,26). In the present study, a higher proportion of trisomy 21 patients (P < 0.01) had a small or very small Y chromosome in comparison to the controls.…”

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Higher Incidence of Small Y Chromosome in Humans with Trisomy 21 (Down Syndrome)

et al. 1982

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SummaryThe length of the Y chromosome was measured in 42 black patients with trisomy 21 (47,XY,+21) and a similar number of normal individuals of American black ancestry. The length of the Y was expressed as a function of Y/F ratio and arbitrarily classified into five groups using subjectively defined criteria as follows: very small, small, average, large, and very large. Thirty-eight % of the trisomy 21 patients had small or very small Ys compared to 2.38% of the controls (P < 0.01). In both populations the size of the Y was not normally distributed. In the normals it was skewed to the left, whereas in the Downs the distribution was flat (platykurtic). A significantly higher incidence of Y length heteromorphisms was noted in the Down as compared to the normal black population. In the light of our current understanding that about one-third of all trisomy 21 patients are due to paternal nondisjunction, it may be tempting to speculate that males with small Y are at an increased risk for nondisjunction of the 21 chromosome. SpeculationThe present study suggests that one-third of trisomy 21 cases have small Y chromosome. Presently, it is believed that approximately one-third of all cases of Down Syndrome are due to "paternal" nondisjunction. Therefore, it is speculated that fathers with small Y chromosome might be at higher risk for nondisjunction for chromosome 21.were unrelated. Lymphocyte metaphases were obtained by a modification of the Moorhead technique (24). At least five to ten GTG (G-bands by Trypsin using Giemsa) (20) banded metaphases 'were from each specimen on high contrast copy film using a Zeiss photomicroscope 111.The four best banded cells were selected from each individual. Chromosomes 19, 20 and Y were directly measured from the negative by projecting the film using a Simmons Omega point light source enlarger (Simmons Omega Inc., N.Y., U.S.A.). The value of "F" was determined as the average length of the four F group chromosomes and the Y/F ratio was calculated for each cell. The final Y/F ratio for the individual was expressed as the average of four-cells. A test of significance ( t test) was performed to examine the differences in the two populations (21). there exists a north/south gradient for the length of the Y in The average length of the Y in ~ontrols and trisomy 21 patients Europeans; men of Mediterranean origin having a longer Y. The were 1.09 and 0.97, respectively; however, the length distribution biologic and clinical significance of human Y chromosome bet-in the controls was skewed to the left whereas in the patients it eromorphisms, however, are poorly understood (12). Although a Was platykuflic. Hence, to compare the average length of the Y longer Y has been reported in criminals (22), no length differences chromosome of one group to another was considered inapprowere observed between criminals and noncriminal controls in priate. several other studies (1,3,4,6,16,17). Consequently, no consistentThe length of the human Y ~h r~m o s o m e is arbitrarily classified relation between th...

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confidence: 45%

Higher Incidence of Small Y Chromosome in Humans with Trisomy 21 (Down Syndrome)

et al. 1982

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Origin of nondisjunction in trisomy 21 syndrome: All studies compiled, parental age analysis, and international comparisons

Juberg

Mowrey

1983

Am. J. Med. Genet.

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The Q-band polymorphism of chromosome 21 permits assignment of the origin of meiotic nondisjunction by parent and meiotic division in a certain proportion of cases. We have compiled all reports through 1982 (including earlier studies using structural abnormality) and have shown that maternal origin accounts for 80% and paternal origin for 20% of trisomic cases. The ratio of first:second meiotic errors among the maternal cases was 80:20 and 60:40 among the paternal cases. Considering maternal and paternal first and second meiotic errors, we showed no differences of either mean maternal or paternal age, though mean maternal age is about 5 yr higher than that of the general population. Comparison of results of six studies from five countries showed similar frequencies by parent and meiotic division with the possible exception of one study from the northeastern United States. The causative role of simply advancing maternal age in nondisjunction is questioned.

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Human chromosomal heteromorphisms in american blacks

Verma

Dosik

1981

Hum Genet

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One hundred normal American Blacks (B) were studied by sequential QFQ and RFA banding techniques in order to estimate the type and frequency of heteromorphisms. Color heteromorphisms were classified into one of six colors by RFA and intensity variation into one of five levels by QFQ. The data are compared with a previously studied Caucasian population (C). The frequencies of QFQ and RFA heteromorphisms were significantly higher in the Black than in the Caucasian population. No racial difference was noted for chromosome 21 by QFQ, while RFA demonstrated a clear difference. It is concluded that the maximum characterization of racial differences of human chromosomal heteromorphisms was far greater by RFA than with QFQ. The present study suggests differences in QFQ and RFA heteromorphisms among the two races.

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Trisomy 21 in a child due to paternal nondisjunction as determined by RFA technique

Cited by 8 publications

References 15 publications

Higher Incidence of Small Y Chromosome in Humans with Trisomy 21 (Down Syndrome)

Higher Incidence of Small Y Chromosome in Humans with Trisomy 21 (Down Syndrome)

Origin of nondisjunction in trisomy 21 syndrome: All studies compiled, parental age analysis, and international comparisons

Human chromosomal heteromorphisms in american blacks

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