Molecular cytogenetic analysis of XX males using Y-specific DNA sequences, including SRY

XX Male: Early Detection With Prenatal Testing

A 46,XX male represents a variant of Klinefelter syndrome (47,XXY), under the category of a disorder of sex development (DSD). Despite possessing an XX karyotype, these individuals exhibit a male phenotype, which, in this case, results from a translocation of the SRY gene from the Y chromosome onto the X chromosome. This genetic alteration results in the development of male gonadal characteristics. This case report outlines a prenatal diagnosis of a 46,XX female in conflict with a level 2 ultrasound. It details the patient's presentation, diagnosis of an SRY-positive 46,XX male, and medical history. The discussion focuses on the advantages of early identification and intervention in managing symptom progression and addressing fertility challenges through hormone replacement therapy. Further exploration of 46,XX DSD early detection and the underlying mechanisms is essential for refining diagnostic and therapeutic approaches that result in a greater quality of life for these patients.

A multi-faceted approach to understanding male infertility: gene mutations, molecular defects and assisted reproductive techniques (ART)

BACKGROUND

The assisted reproductive techniques aimed to assist infertile couples have their own offspring carry significant risks of passing on molecular defects to next generations.

RESULTS

Novel breakthroughs in gene and protein interactions have been achieved in the field of male infertility using genome-wide proteomics and transcriptomics technologies.

CONCLUSION

Male Infertility is a complex and multifactorial disorder.

SIGNIFICANCE

This review provides a comprehensive, up-to-date evaluation of the multifactorial factors involved in male infertility. These factors need to be first assessed and understood before we can successfully treat male infertility.

The epidemiology and etiology of azoospermia

The misconception that infertility is typically associated with the female is commonly faced in the management of infertile men. It is uncommon for a patient to present for an infertility evaluation with an abnormal semen analysis report before an extensive female partner workup has been performed. Additionally, a man is usually considered fertile based only on seminal parameters without a physical exam. This behavior may lead to a delay in both the exact diagnosis and in possible specific infertility treatment. Moreover, male factor infertility can result from an underlying medical condition that is often treatable but could possibly be life-threatening. The responsibility of male factor in couple's infertility has been exponentially rising in recent years due to a comprehensive evaluation of reproductive male function and improved diagnostic tools. Despite this improvement in diagnosis, azoospermia is always the most challenging topic associated with infertility treatment. Several conditions that interfere with spermatogenesis and reduce sperm production and quality can lead to azoospermia. Azoospermia may also occur because of a reproductive tract obstruction. Optimal management of patients with azoospermia requires a full understanding of the disease etiology. This review will discuss in detail the epidemiology and etiology of azoospermia. A thorough literature survey was performed using the Medline, EMBASE, BIOSIS, and Cochrane databases. We restricted the survey to clinical publications that were relevant to male infertility and azoospermia. Many of the recommendations included are not based on controlled studies.

Genetic characterization of two 46,XX males without gonadal ambiguities

PURPOSE

To evaluate hypotheses which explain phenotypic variability in sex determining region Y positive 46,XX males. We investigate two 46,XX males without gonadal ambiguities.

METHODS

Cytogenetic and molecular analyses were used to identify the presence of Y chromosome material and to map the translocation breakpoint. Finally, the pattern of X chromosome inactivation was studied using the methylation assay at the androgen receptor locus.

RESULTS

The presence of Y chromosome material, including the sex determining region Y gene, was demonstrated in both men. However, the amount of translocated Y chromosome material differed between the patients. Different X chromosome inactivation patterns were found in the patients; random in one patient and non-random in the other.

CONCLUSIONS

We found a lack of association between phenotype and X chromosome inactivation pattern. Our cytogenetic and molecular analyses show support for the position effect hypothesis explaining the phenotypic variability in XX males.

Sox3 is required for gonadal function, but not sex determination, in males and females

Sox3 is expressed in developing gonads and in the brain. Evolutionary evidence suggests that the X-chromosomal Sox3 gene may be the ancestral precursor of Sry, a sex-determining gene, and Sox3 has been proposed to play a role in sex determination. However, patients with mutations in SOX3 exhibit normal gonadal determination but are mentally retarded and have short stature secondary to growth hormone (GH) deficiency. We used Cre-LoxP targeted mutagenesis to delete Sox3 from mice. Null mice of both sexes had no overt behavioral deficits and exhibited normal GH gene expression. Low body weight was observed for some mice; overgrowth and misalignment of the front teeth was observed consistently. Female Sox3 null mice (-/-) developed ovaries but had excess follicular atresia, ovulation of defective oocytes, and severely reduced fertility. Pituitary (luteinizing hormone and follicle-stimulating hormone) and uterine functions were normal in females. Hemizygous male null mice (-/Y) developed testes but were hypogonadal. Testis weight was reduced by 42%, and there was extensive Sertoli cell vacuolization, loss of germ cells, reduced sperm counts, and disruption of the seminiferous tubules. We conclude that Sox3 is not required for gonadal determination but is important for normal oocyte development and male testis differentiation and gametogenesis.

Current and future genetic screening for male infertility

Although much of male infertility is currently unexplained, it is likely that underlying defects in critical genes or entire gene pathways are responsible. Because powerful technologies exist to bypass severe male-factor infertility, improving the diagnosis of genetic infertility is important for the infertile couple, not only to explain the problem but also to inform them of conditions potentially transmissible to offspring.

Fetal gender: antenatal discrepancy between phenotype and genotype

Sexual discrepancy is reported in both 46,XY females and 46,XX males, and most diagnoses of sex reversal are made in the postpubertal period. We report three cases of sexual discrepancy, which were revealed by karyotyping following genetic amniocentesis, chorionic villus sampling and fetal blood sampling. The etiologies of 46,XX male, 45,X male and 46,XY female subjects are reviewed. When sexual discrepancy between fetal karyotype and ultrasonographic fetal phenotype is encountered, sample error and placental mosaicism should be excluded. A detailed fetal ultrasound examination should be performed to check for syndromic gender discrepancy. When repeat karyotyping is indicated, localization of the Sox related Y chromosome gene should be carried out.

Molecular, cytogenetic, and clinical characterisation of six XX males including one prenatal diagnosis

Cytogenetic analysis, fluorescent in situ hybridisation (FISH), and molecular amplification have been used to characterise the transfer of Yp fragments to Xp22.3 in six XX males. PCR amplification of the genes SRY, RPS4Y, ZFY, AMELY, KALY, and DAZ and of several other markers along the Y chromosome short and long arms indicated the presence of two different breakpoints in the Y fragment. However, the clinical features were very similar in five of the cases, showing a male phenotype with small testes, testicular atrophy, and azoospermia. All these patients have normal intelligence and a stature within the normal male range. In the remaining case, the diagnosis was made prenatally in a fetus with male genitalia detected by ultrasound and a 46,XX karyotype in amniocytes and fetal blood. Molecular analysis of fetal DNA showed the presence of the SRY gene. FISH techniques also showed Y chromosomal DNA on Xp22.3 in metaphases of placental cells. To our knowledge, this is the second molecular prenatal diagnosis reported of an XX male.

Genetic control of gonadal differentiation

The study of naturally occurring mutations in humans and induced mutations in mice that cause sex reversal has been instrumental in the cloning and functional analysis of genes involved in gonadal differentiation. Several genes required for this complex developmental process have now been identified. The genes LIM1, WT1 and FTZ-F1 have been demonstrated to be involved in the formation of the gonads prior to their differentiation as testes or ovaries. Subsequent sex-specific gonadal differentiation appears to be mediated by the SRY and SOX9 genes in the testis, and the DAX-1 gene in the ovary.

[Genetics of human sex determination and its disturbances]

The genetics of human sex determination is considered in view of the various disorders of gonad development. The Y chromosome plays an important role in the induction of sex determination by encoding the testis-determining factor (TDF). However, not all deviations in regular development can be explained by mutations of the TDF as unique factor. Therefore, it is necessary to postulate other mutations in still unknown genes of the cascade for male-specific determination as well as the requirement of an ovary-determining factor for regular female development.

Molecular cytogenetic analysis of a familial pericentric inversion of chromosome 12

We describe the application of multi-color fluorescence in situ hybridization (FISH) in the characterization of a familial pericentric inversion. Using chromosome 12 short- and long-arm specific DNA probes, fast and reliable discrimination between normal and inversion chromosome 12 or recombinant inversion chromosome 12 was possible. FISH thus provides a reliable means for prenatal detection of balanced or unbalanced chromosome 12 rearrangements in this family. This approach is possible for identification of similar chromosome rearrangements provided that probes for the putatively involved chromosome region are available.