Partial trisomy D: a diagnostic and cytogenetic dilemma. (1/193)

An 18-month-old proposita with psychomotor retardation and other congenital abnormalities is presented. Chromosomal analysis of both parents proved normal. However, the karyotype of the proposita contained 47 chromosomes in both lymphocytes and cultured fibroblasts. The marker chromosome proved to be a deleted No. 14 or 15. Comparison of the reported cases of partial trisomy D indicates that a definitive clinical syndrome is not apparent in either case.  (+info)

Somatic rearrangement of chromosome 14 in human lymphocytes. (2/193)

Ataxia-telangiectasia is a rare genetic disorder associated with immune deficiency, chromosome instability, and a predisposition to lymphoid malignancy. We have detected chromosomally anomalous clones of lymphocytes in eight patients with this disorder. Chromosome banding disclosed that the clones are consistently marked by structural rearrangement of the long arm (q) of chromosome 14. A translocation involving 14q was found in clones obtained from seven of the eight patients whereas a ring 14 chromosome was found in a clone obtained from the other. These findings as well as data obtained by others for patients with ataxia-telangiectasia suggest that structural rearrangement of 14q is the initial chromosomal change in lymphocyte clones of patients with this disorder. Chromosomes of lymphocytes from one of the patients were studied before and after the onset of chronic lymphocytic leukemia. Before leukemia was diagnosed, the patient had a lymphocyte clone with a 14q translocation. This clone appears to have given rise to the leukemic cells. We hypothesize that structural rearrangement of 14q is directly related to abnormal growth of lymphocytes and that it may be a step toward the development of lymphoid malignancies. Increasing evidence, provided by others, for the nonrandom involvement of 14q in African-type Burkitt's lymphoma and other lymphoid neoplasms further strengthens this hypothesis.  (+info)

Loss of Rh antigen associated with acquired Rh antibodies and a chromosome translocation in a patient with myeloid metaplasia. (3/193)

Myeloid metaplasia is a clonal disease of the marrow pluripotent stem cell in which a constant cytogenetic abnormality could result in an altered antigenic characteristic of hematopoietic cells. A 57-yr-old man who had acquired myeloid metaplasia at age 37 was noted to be Rh negative, although blood typing at age 33 was Rh positive. His erythrocytes reacted with anti-c and anti-e, typical for an Rh negative individual. Analysis of 11 metaphase bone marrow cells by G-banding revealed 46 chromosomes with a consistent anomaly in 100% of cells involving chromosomes 1 and 13. The changes were consistent with a reciprocal translocation, with break points at approximately 1p32 and 13q22, although break points at 1p13 and 13q14 were also possible. Since previous cytogenetic data have localized the Rh gene to the short arm of chromosome 1, our data indicate the Rh gene lies within the segment u13 leads to 1p32. Serum of this patient had circulating anti-D and anti-C antibodies. Consequently, this patient lost immunologic tolerance to a "self antigen" after losing the ability to express this antigen.  (+info)

Trisomy 13 and Rubinstein-Taybi syndrome. (4/193)

Initial diagnosis of Rubinstein-Taybi syndrome was made in an infant with a prominent nose and broad thumbs and first toes. However, due to the presence of other anomalies such as low-set, malformed ears, anti-mongoloid slant of the eyes, colobomata of the iris, and cleft palate, cytogenetic studies were carried out and the diagnosis of trisomy 13 was confirmed. Since, occasionally, trisomy 13 syndrome may mimic the Rubinstein-Taybi syndrome, cytogenetic studies should be considered in all patients with clinical diagnosis of Rubinstein-Taybi syndrome.  (+info)

Chromosomal location of the genes for human immunoglobulin heavy chains. (5/193)

We have studied somatic cell hybrids between P3x63Ag8 mouse myeloma cells deficient in hypoxanthine phosphoribosyltransferase (EC 2.4.2.8) and either human peripheral lymphocytes or human lymphoblastoid or myeloma cells for the production of human immunoglobulin chains and for the expression of enzyme markers assigned to each of the different human chromosomes. Human chromosome 14 was the only human chromosome present in all independent hybrids producing mu, gamma, and alpha human heavy chains. In two of the independent hybrids that produced human heavy chains, human chromosome 14 was the only human chromosome present in the hybrid cells. Loss of human chromosome 14 from these hybrids resulted in the concomitant loss of their ability to produce human immunoglobulin heavy chains. In view of these results, we conclude that the genes for human immunoglobulin heavy chains are located on human chromosome 14 in immunoglobulin-producing human cells.  (+info)

Specific chromosome aberrations in ataxia telangiectasia. (6/193)

Cytogenetic observations on seven cases of ataxia telangiectasia are presented. The aberration frequency was found to be increased in all of them with a specificity for the involvement of the D-group chromosomes in rearrangements. Clones of cytogenetically abnormal cells were observed in the lymphocytes of three cases and in the cultured skin fibroblasts of two cases, again with a specificity for D-group involvement. G-banding shows that chromosome 14 is frequently involved in rearrangements in clone cells and that the band 14q12 may be a highly specific exchange point. The significance of lymphocyte clones with a proliferative advantage in vivo is discussed. Cytogenetic studies of the parents and sibs of these cases are also reported.  (+info)

Klinefelter's syndrome associated with a D/D translocation. (7/193)

A case of Klinefelter's syndrome and a simultaneous familial D/D translocation is described. The clinical, endocrine, and psychiatric features were typical of those found in Klinefelter's syndrome. Other family members showed no obvious abnormality despite presence of the D/D translocation.  (+info)

Association of D/D translocations with fetal wastage and aneuploidy. A report of four families. (8/193)

Four families are described with a t(13q14q) segregating. Two of them were identified through index cases with Down's syndrome; their karotypes revealed the unusual 46,XY, -13, -14, +t(13q14q), +21. The other two families were identified through a chromosomal study of parents with repeated spontaneous abortions. Analysis of data on 3 of these 4 families and on 7 other from the published reports showed no evidence of increased fetal wastage among 13/14 carriers. However, the risk of producing offspring with various types of aneuploidy may be greater among carriers than among persons with a normal chromosome pattern. Qualitative and quantitative differences in D/D translocations may account for the observed variation in clinical findings. These differences add to the problem of determining genetic risks from an analysis of grouped data.  (+info)

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