The phenotype of a 45,X male with a Y/18 translocation

A case of 45,X male: genetic reevaluation and hormonal and metabolic follow-up in adult age

OBJECTIVE

To report a case of a 45,X man, a rare condition with a clinical course that has not been dealt with by any previous article in the literature.

DESIGN

Case report.

SETTING

University Genetic Center and Endocrine Clinic.

PATIENT(S)

A 41-year-old man, already known by our genetics center for a 45,X chromosome constitution and a normal male differentiation, came back with requests on his sexual and fertility potential. Twenty-one years ago, high-resolution analysis of prometaphase chromosomes revealed additional euchromatic material on a 15-p chromosome, and in situ hybridization with Y-specific probe pDP105 gave positive signal on 15p11.2, suggesting a t(Yp;15p) translocation.

INTERVENTION(S)

Fluorescence in situ hybridization analyses on metaphase chromosomes, standard oral glucose tolerance test, dynamic hormone assays, semen analysis, and dual-energy x-ray absorptiometry.

MAIN OUTCOME MEASURE(S)

Reexamination at clinical, genetic, hormonal, and metabolic level.

RESULT(S)

The derivative chromosome 15 was characterized as der(15)(Ypter-->q11.21::15p11.2-->qter). The patient's findings satisfied the criteria of the metabolic syndrome. Hypergonadotropinemic hypotestosteronemia was diagnosed.

CONCLUSION(S)

Our study offers new insights into the natural history of this condition and suggests that hypogonadism could play a role in the development of metabolic syndrome.

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.

18p deletion syndrome with a 45, XY, t (14; 18) (p11;q11.2), -18, karyotype

A dysmorphic male child of 8 months age presented with microphthalmia, micrognathia, hypertelorism, wide anterior fontanelles, large forehead, short neck, prominent ears, macrotestis and delayed developmental milestones. The patient presented with generalised seizures hydrocephalaus and Coarctation of aorta (Pre subclavian). He also had mild hypocalcaemia with normal renal function. Cytogenetic study revealed 18p(-) picture due to translocation between 14 p & 18q. Since the spectrum of clinical expression is similar to that is seen in 18p(-) syndrome it is suggested that not only whole of 18p but part of chromosome no. 18 proximal to 18 q 11.2 may also be involved in this phenotype.

Del(18p) shown to be a cryptic translocation using a multiprobe FISH assay for subtelomeric chromosome rearrangements

We have previously described a fluorescence in situ hybridisation (FISH) assay for the simultaneous analysis of all human subtelomeric regions using a single microscope slide. Here we report the use of this multiprobe FISH assay in the study of a patient whose karyotype was reported by G banding analysis as 46,XX,del(18)(p11.2). Although the proband had some features suggestive of a chromosomal abnormality, relatively few of the specific features of del(18p) were present. She was a 37 year old female with mild distal spinal muscular atrophy (SMA), arthritis of the hands, an abnormal chest shape (pectus excavatum), and an unusual skin condition (keratosis pilaris). Reverse chromosome painting with degenerate oligonucleotide primer-polymerase chain reaction (DOP-PCR) amplified del(18p) chromosomes as a probe confirmed the abnormality as del(18p), with no evidence of any other chromosome involvement. Subsequently, the multiprobe FISH assay confirmed deletion of 18p subtelomeric sequence. However, the assay also showed that sequences corresponding to the 2p subtelomeric probe were present on the tip of the shortened 18p. The patient is therefore monosomic for 18p11.2-pter and trisomic for 2p25-pter, and the revised karyotype is 46,XX,der(18)t(2;18)(p25; p11.2). We believe that a proportion of all cases reported as telomeric deletions may be cryptic translocations involving other chromosome subtelomeric regions. Further studies such as this are necessary to define accurately the clinical characteristics associated with pure monosomy in chromosomal deletion syndromes.

Turner syndrome and haploinsufficiency

Turner syndrome was one of the first human genetic disorders ascribed to haploinsufficiency but the identification of specific genes responsible for the phenotype has been problematic. Recent data point to several candidate genes, some new and some old, for specific aspects of the phenotype associated with monosomy X in humans.

Interstitial insertion of Y-specific DNA sequences including SRY into chromosome 4 in a 45,X male child

A 45,X chromosome complement was found in the lymphocytes and skin fibroblast cultures of a male infant with minor facial anomalies and gastrointestinal abnormalities. Fluorescence in situ hybridization (FISH) studies with DNA probes specific for the entire Y chromosome (painting) and SRY identified insertion of a short piece of Y chromosome DNA, including the SRY region, into a der(4) chromosome at 4p15. FISH studies with DNA probes specific for Wolf-Hirschhorn syndrome (WHS) and telomere of 4p indicated that these 2 regions were intact and that the insertion of Y DNA had occurred proximal to the WHS region. High-resolution chromosome analysis performed after FISH studies showed an altered banding pattern of 4p at the region of insertion. The typical Giemsa dark band of 4p15 was consistently replaced by a gray band; this probably indicates deletion of the distal part of 4p15. The consequences of the double-chromosome anomaly in this patient were discussed in relation to his phenotype.