Parental origin of the X chromosome in a patient with a Robertsonian translocation and Turner's syndrome.

We report on a proband with both a Robertsonian translocation and Turner's syndrome. Study of the parental origin of the X chromosome performed by microsatellite analysis indicates paternal origin of the X chromosome (Xpat). The occurrence of chromosome aberrations as a consequence of interchromosomal interactions is discussed.

Clinical and meiotic studies in an infertile man with Y;13 translocation.

Clinical and meiotic studies were done on an infertile man with a translocation between Yq and 13q, who was identified through the birth of his son with partial trisomy 13q. Seminal plasma transferrin showed preserved Sertoli cell function while lactate dehydrogenase C4 indicated hypospermatogenesis. A quadrivalent in diakinesis and spermatogenic arrest in the second meiotic division was detected.

Evidence for a compensatory mechanism regulating Ag-NOR activity in families with de novo 21;21 translocation Down syndrome.

Nucleolus organizing region (NOR) activity in seven probands with Down syndrome due to a de novo (21;21) translocation and their parents was analyzed on the basis of total Ag-NOR size per cell, mean Ag-NOR size per cell (Xc), mean Ag-NOR size per acrocentic (Xa), and the characteristic Ag-NOR number of each subject. The results showed intercellular variations in total Ag-NOR size per cell in all subjects, as well as interindividual variations in mean Ag-NOR size per cell. When the subjects were grouped according to their characteristic Ag-NOR number and the mean Ag-NOR size per cell for each group (GXc) and the mean Ag-NOR size per acrocentric for each group (GXa) were calculated, a number of interesting and significant correlations were found: (1) GXc correlated perfectly with the group's characteristic Ag-NOR number, (2) GXa varied inversely with the group's characteristic Ag-NOR number, and (3) GXc and GXa varied inversely with each other. These results suggest that if the Ag-NOR number of a cell decreases, the total NOR activity of the cell also decreases, but the NOR activity of its chromosomes increases. This finding supports the existence of a compensatory mechanism that regulates NOR activity on the cellular level.

De novo 21/21 translocation Down syndrome. Studies of parental origin of the translocation and acrocentric associations in parents.

Among ten families with de novo 21/21 translocation Down syndrome (tDS), four were informative, according to the studies of structural variants of chromosome 21, about the origin of the aberrant chromosome. In three of these, the translocation originated in the paternal and in one in the maternal gametogenesis. The parents with meiotic failure were compared with 20 control individuals (10 males and 10 females). There were no significant differences between them in the association coefficient of chromosome 21 and in the frequency of 21-21 associations. Similar results were obtained previously with the entire sample of tDS parents. The results obtained, unless they reflect too small a sample, suggest that the origin of the aberrant chromosome is not related to an increased chromosome 21 association tendency. It could be supposed that in the case of an apparent 21/21 translocation, the 21q isochromosome, morphologically indistinguishable from the Robertsonian translocation, is in question. The Ag-NOR negative acrocentrics in the tDS parents reappeared in the probands confirming the heritability of that nucleolus organizer regions (NOR) trait.

Tandem duplication of chromosome 14 (q24 leads to q32) in male newborn with congenital malformations.

A tandem duplication of 14q24 leads to q32, estimated by G- and R-banding, was found in a male newborn with growth retardation and congenital malformations. His clinical picture is compared with that of three patients from the literature with partial trisomy for a similar segment of 14q due to a parental reciprocal translocation or a de novo translocation.

NORs and satellite associations in a family with 13/14 translocation.

The distribution and size of Ag-NORs and the frequency of satellite associations was investigated in a family where the mother and a son were 13/14 translocation carriers. In cells with good quality silver impregnation and G-banding, Ag-NORs were constant per subject in number and distribution, while Ag-NOR size varied from cell to cell. The father had the maximal number Ag-NORs (10). The mother's translocation chromosome, free chromosome 13 and both chromosomes 22 were Ag-NOR negative and these were transmitted to the children. The mean number of associations per cell for a particular subject was positively correlated with the subject's characteristic number of Ag-NORs. In this family, the positive correlation was also present between mean Ag-NOR size of acrocentric homologue chromosome pairs and their coefficient of association. No biological mechanism compensating for the absence of active NORs was demonstrated for this family.

13/14 Translocation in a man with reproductive failure. Mitotic and meiotic studies.

An inherited (maternal origin) 13/14 translocation with the nucleolus organizer regions eliminated and one centromere was found in an oligospermic man whose wife had had two spontaneous abortions. Meiotic studies revealed all stages of spermatogenesis with a trivalent configuration in diakinesis. Possible reasons for his subfertility and his mother's normal fertility are discussed.

Infrequent structural chromosome aberrations in women with primary amenorrhea.

Since the problem of primary amenorrhoea (PA) is very real the authors reviewed a series of 58 women from their own laboratory, citing all known causes of PA and emphasizing that the most interesting cases are those with normal karyotype. Reinvestigation of patients with normal karyotype using the banding methods (G and R) revealed new types of structural aberrations of X chromosome. The importance of structural disturbances and rearrangements of particular segments of X chromosome in the etiology of PA has been discussed.

Recombinant chromosome as a result of pericentric inversion of X chromosome.

A structural X chromosome abnormality was found in the karyotype of a tall patient with gonadal dysgenesis and with no extragenital anomalies. Based on her mother's karyotype, which showed a pericentric inversion of the X chromosome: 46,X,inv(X)(p22q24), as well as from G and R banding, we concluded that the abnormal X chromosome of our patient was a recombinant chromosome that had originated as a result of one crossing over in the inversion loop during gametogenesis in her mother. The recombinant X chromosome had a partial delection of Xq and a partial duplication of Xp: 46,X,rec(S),dup p,inv(X)(p22q24). After BUDR incorporation, the abnormal X chromosome of the patient and that of her mother showed a late replication. The karyotype-phenotype correlation and the nonrandom inactivation of the inverted X chromosome in the mother are discussed.