Two cases of Y; autosome translocations: A 45,X male and a clinically trisomy 18 patient

A unique case of growth hormone and human chorionic gonadotropin treatment in a 45,X male with Y: autosome translocation and literature review

Maleness associated with a 45,X karyotype is a rare condition in childhood. It is usually diagnosed in adult age because of infertility. We report a unique case of an unbalanced translocation t(Y;21) in a 14-year-old boy with 45,X karyotype referred because of short stature, thin habitus and puberty delay. Hormone analysis showed low serum levels of basal testosterone, insulin-like growth factor (IGF-I) and gonadotrophins. Diagnosis of GH deficiency and puberty delay were made. He was treated with human chorionic gonadotropin (hCG) and GH therapy, respectively, for 6 and 24 months.

Characterization of a de novo unbalanced Y;autosome translocation in a 45,X mentally retarded male and literature review

OBJECTIVE

To describe the molecular and cytogenetic characterization of a de novo unbalanced Y;autosome translocation in a 45,X mentally retarded male.

DESIGN

Descriptive case study and literature review.

SETTING

Tertiary medical center.

PATIENT(S)

A 17-year-old 45,X mentally retarded male with no stigmata of Turner syndrome.

INTERVENTION(S)

Molecular and cytogenetic investigations, physical examination, and hormonal assays.

MAIN OUTCOME MEASURE(S)

Cytogenetic analysis, fluorescence in situ hybridization (FISH), array comparative genomic hybridization (CGH), and polymorphic DNA marker analysis.

RESULT(S)

The FISH showed a Y/18p translocation. Array CGH revealed a loss of distal chromosome 18p material and a loss of part of Yq material corresponding to deletions of chromosomal segments of 18pter-->18p11.2 and Yq11.221-->Yqter. Polymorphic DNA markers analysis showed that the X chromosome was of maternal origin and the deletion of 18p was of paternal origin.

CONCLUSION(S)

This study confirms the usefulness of array CGH in the detection of subtle chromosomal rearrangements resulting in an unbalanced Y;autosome translocation.

α-thalassemia/mental retardation syndrome in a 45,X male

An unbalanced Y;autosome translocation leading to a male with a 45,X karyotype is rare with about 30 published cases. A male with a 45,X karyotype as a result of a unique, submicroscopic, unbalanced Y;16 translocation is presented with alpha-thalassemia/mental retardation syndrome.

Prenatal diagnosis of a 45,X male with a SRY-bearing chromosome 21

Male phenotype associated with a 45,X karyotype is an infrequent finding. We present a case diagnosed prenatally on amniocentesis performed for maternal age. The male phenotype was associated with a translocation of a distal part of Yp including the pseudoautosomal SHOX gene and SRY gene on the short arm of a chromosome 21. By DNA analysis we could show that the X chromosome was of maternal origin and that the breakpoint was in interval 3 of the Y chromosome. Mechanisms and genetic counselling are discussed based on a review of published cases of 45,X and XX males.

A 45,X sterile male with Yp disguised as 21p

An azoospermic male was found to have, by means of banding techniques, a 45,X karyotype including a monocentric chromosome 21 with an euchromatic short arm that looked similar to Yp. This rearranged chromosome was further characterized by FISH with a whole Y chromosome paint and the alphoid repeats DYZ3 and D13Z1/D21Z1; the former probe gave a positive signal onto such a peculiar arm without spreading into the long arm, whereas the alphoid repeats revealed an apparent compound centromere with Y- and 21-sequences. Therefore, an unbalanced Y;21 whole arm translocation was concluded and the karyotype written as 45,X.ish der(Y;21)(p10;q10)(wcpY+,DYZ3+,D13Z1/D21Z1+). This patient represents the first case of a Y;21 translocation in an apparent 45,X male, constitutes the fifth instance of a 45,X sterile male, and conforms to previously established karyotype-phenotype correlations.

Molecular and cytogenetic characterization of an azoospermic male with a de-novo Y;14 translocation and alternate centromere inactivation

BACKGROUND

Y-autosome (Y/A) translocations have been reported in association with male infertility. Different hypotheses have been made as to correlations between Y/A translocations and spermatogenetic disturbances. We describe an azoospermic patient with a de-novo Y;14 translocation: 45,X,dic(Y;14)(q12;p11).

METHODS AND RESULTS

Cytogenetic, fluorescent in-situ hybridization (FISH) and molecular studies have been performed. A 14/22 (D14Z1/D22Z1) centromere and a Y centromere (DYZ1) probe both showed a signal on the translocation chromosome, confirming its dicentricity. Each copy of the translocation chromosome had only one primary constriction, with inactivation of the Y centromere in most (90%) of the cells. The 14 centromere was inactive in the remaining cells (10%). FISH and molecular deletion mapping analysis allowed acute assignment of the Yq breakpoint to the junction of euchromatin and heterochromatin (Yq12), distal to the AZF gene location (Yq11).

CONCLUSIONS

This study supports the hypothesis that in Y/A translocations infertility might be related to meiotic disturbances with spermatogenetic arrest. In addition, sex chromosome molecular investigations, performed on single spermatids, suggest a highly increased risk of producing chromosomally abnormal embryos.

PCR analysis of Y-chromosome sequences in a 45,X male patient and a review of the literature

The 45,X karyotype is usually associated with Turner syndrome, while male phenotype is exceptional. The authors report a 45,X male patient with normal external genitalia and sex behavior, but who was azoospermic. He had a normally developed musculature and pilose distribution, testicular volume of 15 mL and no gynecomastia but clinical stigmata of Turner syndrome (short stature, short neck and 4th metacarpal bones) and azoospermia. Hormonal plasma levels of testosterone, estradiol, prolactin, and gonadotrophins were within the normal range as was the response of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) (30 and 60 min) after 100 microg iv of LH-RH administration. Testicular biopsy could not be performed. Karyotype was 45,X without evidence of mosaicism. Polymerase chain reaction of genomnic DNA studied with 12 different sequences of Y chromosome revealed only the presence of SRY gene (testis determining factor). It is possible that SRY/autosomal translocation had occurred in this patient. The study of 45,X male should be of great value in elucidating the complex mechanisms involved in normal male sex differentiation.

Clinical management of a rare de novo translocation 46,X,t(Y;15) (p11.2 approximately 11.3;q11.2).ish t(Y;15)(DYZ3+,AMELY+,SNRPN+;D15Z+) found prenatally

A 40-year-old woman had amniocentesis at 16 weeks' gestation. Chromosome studies based on 15 colonies showed a de novo 46,X,t(Y;15)(p11.2 approximately 11.3;q11.2) karyotype. Using C- and Q-banding, the additional material on 15 appeared to be Yqh heterochromatin. The satellite on the small derivative chromosome was positive by AgNOR staining. Fluorescence in situ hybridization (FISH) studies using Y and 15 alpha satellite centromeric probes (DYZ3 and D15Z) showed that the derivative chromosome that resembled 15p+ had a Y centromere and that the satellited derivative had a 15 centromere. The break on Y was distal to the amelogenin locus and on 15 it was shown to be proximal to the Prader Willi/Angelman region by using the SNRPN probe. DNA studies ruled out uniparental disomy of chromosome 15 and a SRY deletion. The pregnancy was continued and a normal baby boy without any discernible abnormalities was born.

Detection of Y chromosome sequences in a 45,X/46,XXq--patient by Southern blot analysis of PCR-amplified DNA and fluorescent in situ hybridization (FISH)

In some cases of gonadal dysgenesis, cytogenetic analysis seems to be discordant with the phenotype of the patients. We have applied techniques such as Southern blot analysis and fluorescent in situ hybridization (FISH) to resolve the phenotype/genotype discrepancy in a patient with ambiguous genitalia in whom the peripheral blood karyotype was 45,X. Gonadectomy at age 7 months showed the gonadal tissue to be prepubertal testis on the left side and a streak gonad on the right. The karyotype obtained from the left gonad was 45,X/46,XXq- and that from the right gonad was 45,X. Three different techniques, PCR amplification, FISH, and chromosome painting for X and Y chromosomes, confirmed the presence of Y chromosome sequences. Five different tissues were evaluated. The highest percentage of Y chromosome positive cells were detected in the left gonad, followed by the peripheral blood lymphocytes, skin fibroblasts, and buccal mucosa. No Y chromosomal material could be identified in the right gonad. Since the Xq- chromosome is present in the left gonad (testis), it is likely that the Xq- contains Y chromosomal material. Sophisticated analysis in this patient showed that she has at least 2 cell lines, one of which contains Y chromosomal material. These techniques elucidated the molecular basis of the genital ambiguity for this patient. When Y chromosome sequences are present in patients with Ullrich-Turner syndrome or gonadal dysgenesis, the risk for gonadal malignancy is significantly increased. Hence, molecular diagnostic methods to ascertain for the presence of Y chromosome sequences may expedite the evaluation of patients with ambiguous genitalia.

Y Chromosomal Sequences Identified in Gonadal Tissue of Two 45,X Patients with Turner Syndrome

We examined excised gonadal tissue obtained from two 45,X patients for evidence of Y chromosomal material. Both patients had features atypical for individuals with Turner syndrome, a large dysgerminoma in patient 1 and clitoromegaly in patient 2. Southern blot analysis of polymerase chain reaction (PCR)-amplified DNA was performed for five Y chromosome-specific probes (SRY, ZFY. DYZ3, KALY, and DYZ1). Fluorescence in situ hybridization (FISH) with a combination probe specific for the DYZ1/DYZ3 loci was utilized. For both patients, Southern blot analysis of PCR-amplified DNA with primers for the SRY gene was positive. No signals were detected with the other Y chromosome-specific probes for patient 1. For patient 2, positive signals were obtained for all-Y-specific probes. FISH was negative in the gonadal specimen from patient 1, while rare cells were positive in the sections from patient 2. Turner syndrome and mixed gonadal dysgenesis may represent different points on a continuum of disorders of sexual differentiation. Although the risk for gonadal tumors is considered to be low in patients with Turner syndrome, prospective evaluation is critical to ascertain: The frequency of somatic cell mosaicism for cell lines carrying Y chromosomal material, and how the presence of Y chromosomal material in patients with Turner syndrome affects the propensity for virilization and gonadal neoplasms.