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.

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 present report deals with a new case of monosomy X combined with t(13;14). As the translocation was paternally inherited, we wanted to evaluate if the second aberration (XO) had the same origin. Simple dinucleotide sequence repeats have been shown to be highly polymorphic and useful in genetic analysis since they are readily assayed by PCR.3 Therefore, we based our analysis on the microsatellite marker located at the extreme terminus of the dystrophin gene.4The proband, a 16 year old girl, was admitted to hospital because of short stature and primary amenorrhoea. Physical examination showed phenotypic characteristics of Turner's syndrome: small mandible, epicanthic folds, hypertelorism, low set ears, short neck with pterigium and low W shaped posterior hair line, shield chest, undeveloped breasts with widely spaced hypoplastic nipples, cubitus valgus, short fourth and fifth metacarpals, short fifth finger with clinodactyly, and gonadal dysgenesis. Her intelligence was normal. At the time of birth her mother was 22 and her father was 23 years old. Her parents had a second daughter, six years younger and phenotypically normal. The mother had no history of spontaneous abortion and the father is a phenotypically normal male.Chromosome analysis was performed on trypsin G banded chromosome preparations from peripheral lymphocyte cultures; 50 metaphases were scored.Polymerase chain reaction was carried out on DNA extracted from blood samples. The oligonucleotides4 allowed the amplification of markers DYS 1 and DYSI 1 1, with a size range of 177 to 185 bp and 219 to 225 bp, respectively. Reactions and conditions of the amplification were as described by Feener et al4 and the PCR products were electrophoresed on a 5% non-denaturing polyacrylamide gel (figure A). The alleles of the marker were separated on a 10% non-denaturing polyacrylamide gel and visualised by ethidium bromide staining (figure B).In the proband's lymphocytes, besides monosomy X, cytogenetic analysis showed the presence of a Robertsonian translocation: 44,X,t(1 3q; 14q) (data not shown). The translocation chromosome was inherited from her father, whose karyotype was 45,XY,t(13q;14q). The karyotypes of her mother and sister were normal.Amplification of the DYS1 marker was not informative in our family (data not shown).

Partial karyotypes showing chromosomes 13 and Y using Ag-NOR-G banding and C banding (proband, top two rows, father, bottom two rows).

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.

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.