Biomedical subjects
Publications and source records attributed to D Soudek.
In situ hybridization with a c-sis probe was performed on peripheral lymphocytes of a man with neurofibromatosis and a ring 22 chromosome. Hybridization was observed on both the normal #22 and the ring 22, indicating that the patient is not constitutionally hemizygous for c-sis. The implications of a ring 22 constitution and the neurofibromatosis phenotype are discussed.
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A review of 61 males with the fragile X positive form of the Martin Bell syndrome from 30 families seen in the past 4 years suggests that the number of lymphocytes with the fragile site on the X chromosome (fra(X) ) in retarded males tends to be characteristic for the individual and similar to that found in other retarded males in the same family. The number of lymphocytes with fra(X) was not correlated with height, weight, occipitofrontal circumference, ear length or mean testicular volume in adults nor with age over the whole series.
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Eberle et al. (1981, 1982a) reported diminished proportion of fragile X chromosomes in co-cultures of blood cells taken from fra(X) patients with normal blood cells. However, we did not observe any suppression of fra(X) in the blood of fra(X)-positive patients after co-cultivation with blood of fra(X)-negative subjects. Neither was any suppression caused by medium where fra(X)-negative cells had been previously cultivated for two days.
In a study of 41 inpatient boys with psychiatric disorders, it was found that this group had significantly increased length of the long arm of the Y chromosome (Yq+) as compared to a normal control group. The length of the Y chromosome in the inpatient group correlated with psychiatric symptom severity, hyperactivity, parental psychopathology and paternal alcoholism. A further study of minor chromosomal variants in 56 inpatient boys and girls revealed no differences in individual or pooled variants in the patient group, as compared to the control group. However, those in the patient group with one or more variants showed more severe psychiatric and other psychosocial symptoms than those in the group without variants. Those who had both longer Y chromosomes and a minor chromosomal variant had more severe psychiatric symptom severity.
Chromosome 13p+ was identified in an amniotic cell culture. The variant has been inherited for three generations without adverse effect.
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The possible phenotypic effect of chromosomal variants is as yet an unsolved problem. QM- and C-banded chromosomes of 100 male patients with idiopathic mental retardation were compared with chromosomes of 100 Royal Military College cadets, as controls. Increased size of 9qh seems to be a factor with possible negative effects. 9qh- was found to be more common in the control sample. Another variant found more often in the retarded subjects was 16qh-. Increased frequencies of Yq+ or small inversions in chromosomes 3 and 9 were not found in the retarded.
The frequency of the 'inversion' of flourescent constitutive heterochromatin in chromosome 3 was the same in a sample of 370 retarded persons as in a sample of 222 mentally normal men. It can be concluded that this 'inversion' is not associated with mental retardation. This variant is more common (4%) in the Canadian population we studied than in samples reported by most other authors (0-1.7%). Possibly the founder effect could play a role in the differences. Two cases of homozygotes for this 'inversion' were identified.
An infant with ambiguous genitalia, uterus, tubes, and bilaterally undescended testes was found to have an unstable dicentric Yq chromosome, and 45,X/46,X,dic i(Yq)/47,X,i(Yq) i(Yq) mosaicism in lymphocytes and fibroblasts. A few other minor cell lines were found in peripheral blood lymphocytes. These findings indicate a high degree of mitotic instability in the centromere of the dicentric i(Yq) chromosome in this patient.
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The C-bands of two cases of familial, genetically inactive, accessory small chromosomes and five cases of genetically active chromosomes were examined. Inactive chromosomes consist of constitutive heterochromatin and satellites only. In active chromosomes, euchromatin was present. These chromosomes contained two, one or no C-bands, although all these chromosomes were morphologically monocentric. C-banding is more informative than other banding methods for this category of chromosomes.
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A phenotypically normal male has a small Y chromosome with no Yq fluorescence, but displays constitutive heterochromatin on the end of Yq. C and Q bands on Yq therefore need not be necessarily identical.
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