A minority of 46,XX true hermaphrodites are positive for the Y-DNA sequence including SRY

Molecular analysis in true hermaphrodites with different karyotypes and similar phenotypes

True hermaphroditism is characterized by the development of ovarian and testicular tissue in the same individual. Müllerian and Wolffian structures are usually present, and external genitalia are often ambiguous. The most frequent karyotype in these patients is 46,XX or various forms of mosaicism, whereas 46,XX is very rarely found. The phenotype in all these subjects is similar. We studied 10 true hermaphrodites. Six of them had a 46,XX chromosomal complement: 3 had been reared as males and 3 as females. The other 4 patients were mosaics: 3 were 46,XX/46,XY and one had a 46,XX/47,XXY karyotype. One of the 46,XX/46,XY mosaics was reared as a female, whereas the other 3 mosaics were reared as males. The sex of assignment in the 10 patients depended only on labio-scrotal differentiation. Molecular studies in 46,XX subjects documented the absence of Y centromeric sequences in all cases, arguing against hidden mosaicism. One patient presented Yp sequences (ZFY+, SRY+), which contrast with South African black 46,XX true hermaphrodites in whom no Y sequences were found. Molecular analysis in the subjects with mosaicism demonstrated the presence of Y centromeric and Yp sequences confirming the presence of a Y chromosome. Gonadal development, endocrine function, and phenotype in the 10 patients did not correlate with the presence of a Y chromosome or Y-derived sequences in the genome, confirming that true hermaphroditism is a heterogeneous condition.

Clinical and genetic variability in XX sex-reversed patients

Three 46, XX hypogonadal subjects are described who exhibited different clinical and genetic characteristics. Two patients, with complete sex-reversal, are sterile males with hypogonadal features; the third patient, with partial sex-reversal, presented with a eunuchoid appearance and with ambiguous genitalia. Polymerase chain reaction (PCR) amplification of DNA from these patients showed the presence of a translocation of the sex-determining region of the Y chromosome (Sry) only in the first two patients described.

Agonadism in two sisters with XY gonosomal constitution, mental retardation, short stature, severely retarded bone age, and multiple extragenital malformations: a new autosomal recessive syndrome

We report on 12- and 14-year old sisters with a 46, XY chromosome constitution, normal female external genitalia, and absence of gonadal tissue. Except for omphalocele, right renal agenesis and malrotation of the colon in the elder sister, the internal organs were normal. Both were mentally retarded, of short stature, and had extremely retarded bone age. In addition, they had an almost identical pattern of minor anomalies: peculiar face, hypodontia, short neck, inverted nipples, thoracolumbar scoliosis, "dysplastic" hips, partial clino-/syndactyly of toes. The occurrence of a basically similar set of malformations in two sisters and the first cousin consanguinity of the parents suggests autosomal recessive inheritance. The conserved region of the SRY gene ([high mobility group] HMG box) was sequenced in the elder sib and was normal. No consistent malformations are observed at present in agonadal patients. This supports the idea that several autosomal genes have the potential of influencing the sequence of events of sex determination.

PCR-based study of the presence of Y-chromosome sequences in patients with Ullrich-Turner syndrome

The presence of Y chromosome sequences in Ullrich-Turner syndrome (UTS) patients has been suggested in previous work. Karyotype analysis estimated at about 60% of patients with a 45, X constitution and molecular analysis (Southern blot analysis with several Y chromosome probes and PCR of specific sequences) identified the presence of Y chromosome material in about 40% of 45, X patients. We have developed a very sensitive, PCR-based method to detect Y specific sequences in DNA from UTS patients. This protocol permits the detection of a single cell carrying a Y sequence among 10(5) Y-negative cells. We studied 18 UTS patients with 4 Y-specific sequences. In 11 patients we detected a positive amplification for at least one Y sequence. The existence of a simple and sensitive method for the detection of Y sequences has important implications for UTS patients, in view of the risk for some of the females carrying Y-chromosome material of developing gonadoblastoma and virilization. Additionally, some of the UTS associated phenotypes, such as renal anomalies, could be correlated with the presence of Y chromosome specific sequences.

Sry-negative XX sex reversal in the American cocker spaniel dog

The Sry gene product serves an important function in male sex determination through testis induction. However, testicular development has been reported in SRY-negative XX sex reversed humans. XX sex reversal of the American cocker spaniel, inherited as an autosomal recessive trait, may be a homolog of this disorder. The purpose of this study was to determine whether the Sry high mobility group (HMG) box is present in genomic DNA of affected dogs. Conserved Sry HMG box and hypoxanthine phosphoribosyltransferase (HPRT) sequences were used as primers in polymerase chain reactions. A 167 bp Y-specific canine Sry HMG box sequence was cloned from genomic DNA of normal male dogs. Internal primers generated a 104 bp Sry HMG box product from normal males, but not from females or XX sex reversed dogs. Parallel reactions generated an HPRT product from all dogs. Results indicate that the Sry HMG box is absent in genomic DNA of XX sex reversed dogs. We speculate that activation of the testis differentiation cascade in the absence of Sry in this model is due to a mutant autosomal gene.

XX true hermaphroditism in southern African blacks: exclusion of SRY sequences and uniparental disomy of the X chromosome

A molecular investigation of 16 Bantu-speaking Black XX true hermaphrodites was undertaken in an attempt to determine the cause of the disorder. Y-specific sequences, including sequences mapping to the sex-determining region of the Y, were shown to be absent from lymphocyte tissue of all 16 patients tested. Y chromosome sequences were also absent from the ovarian and testicular components of both ovotestes of a single XX true hermaphrodite, thus excluding gonadal mosaicism involving Y chromosome sequences. Since there is evidence for Xp genes involved in testis determination/differentiation, uniparental disomy of the X chromosome was investigated in 14 XXTH families. Uniparental disomy was excluded in 12 of the 14 families, and isodisomy was excluded in the remaining two cases.

Genetic analysis of 38XX males with genital ambiguities and true hermaphrodites in pigs

In pig, the frequency of intersexuality ranges from 0.1 to 0.6%, depending on the breed. In a closed pig herd at INRA an intersex condition was observed in 0.75% of 'females'. The present study describes 11 animals with a 38XX karyotype and the presence of testicular tissue. Phenotypically, all presented with abnormal external or/and internal genitalia. Southern blot analysis with Y-specific probes (SRY and ZFY) revealed the absence of Y material in all animals tested. By polymerase chain reaction (PCR) amplification, 10 of 11 intersex pigs lacked the SRY gene in gonad DNA. These data are compatible with an autosomally (or pseudoautosomally) determined mechanism. Moreover, analysis of familial cases seemed to indicate that 38XX male pseudohermaphrodites and 38XX true hermaphrodites may represent alternative manifestations of the same genetic defect.

Clinical and anatomical spectrum in XX sex reversed patients. Relationship to the presence of Y specific DNA-sequences

OBJECTIVE

Testicular differentiation can occur in the absence of the Y chromosome giving XX sex-reversed males. Although Y chromosomal sequences can be detected in the majority of male subjects with a 46,XX karyotype, several studies have shown that approximately 10% of patients lack Y material including the SRY gene. The aim of this study was to see if the classification of XX sex-reversed individuals into three groups, Y-DNA-positive phenotypically normal XX males, Y-DNA-negative XX males with genital ambiguities and Y-DNA-negative true hermaphrodites can be applied to our cases.

DESIGN

Endocrinological and genetic studies were conducted in 20 XX sex-reversed patients.

PATIENTS

Twenty patients with various phenotypes were studied. They were between 20 days and 35 years old. Ten presented ambiguous external genitalia (Prader's stages II to IV). After laparotomy or gonadal biopsy, the diagnosis was 46,XX true hermaphroditism in five, and XX male in 15.

MEASUREMENTS

Blood samples were obtained from all patients for hormonal and molecular studies. Basal levels of testosterone, oestradiol and pituitary gonadotrophins were measured by RIA. In addition, two stimulation tests were performed: gonadotrophin stimulation with GnRH and testicular stimulation with hCG. Several Y-specific DNA sequences of the short arm of the Y chromosome were analysed by Southern blot and polymerase chain reaction methods.

RESULTS

In this study, three categories of XX sex-reversed individuals were observed: phenotypically normal males with or without gynaecomastia, males with genital ambiguities, and true hermaphrodites. Endocrinological data were similar in XX males and in true hermaphrodites. Testosterone levels exhibited normal (n = 9) or decreased (n = 11) values. The hCG response was low. FSH and LH were elevated in 13 patients. Molecular analysis in ten patients showed varying amounts of Y material including the Y boundary and SRY. Ten patients with various phenotypes lacked Y chromosomal DNA. There was no relation between Leydig cell function (as indicated by testosterone levels before or after hCG stimulation) and the presence of Y chromosome material.

CONCLUSION

Although the presence of Y-specific DNA generally results in a more masculinized phenotype, exceptions do occur. In the Y-DNA-negative group, complete or incomplete masculinization in the absence of SRY suggests a mutation of one or more downstream non-Y, testis-determining genes.

Gender verification in competitive sports

The possibility that men might masquerade as women and be unfair competitors in women's sports is accepted as outrageous by athletes and the public alike. Since the 1930s, media reports have fuelled claims that individuals who once competed as female athletes subsequently appeared to be men. In most of these cases there was probably ambiguity of the external genitalia, possibly as a result of male pseudohermaphroditism. Nonetheless, beginning at the Rome Olympic Games in 1960, the International Amateur Athletics Federation (IAAF) began establishing rules of eligibility for women athletes. Initially, physical examination was used as a method for gender verification, but this plan was widely resented. Thus, sex chromatin testing (buccal smear) was introduced at the Mexico City Olympic Games in 1968. The principle was that genetic females (46,XX) show a single X-chromatic mass, whereas males (46,XY) do not. Unfortunately, sex chromatin analysis fell out of common diagnostic use by geneticists shortly after the International Olympic Committee (IOC) began its implementation for gender verification. The lack of laboratories routinely performing the test aggravated the problem of errors in interpretation by inexperienced workers, yielding false-positive and false-negative results. However, an even greater problem is that there exist phenotypic females with male sex chromatin patterns (e.g. androgen insensitivity, XY gonadal dysgenesis). These individuals have no athletic advantage as a result of their congenital abnormality and reasonably should not be excluded from competition. That is, only the chromosomal (genetic) sex is analysed by sex chromatin testing, not the anatomical or psychosocial status. For all the above reasons sex chromatin testing unfairly excludes many athletes. Although the IOC offered follow-up physical examinations that could have restored eligibility for those 'failing' sex chromatin tests, most affected athletes seemed to prefer to 'retire'. All these problems remain with the current laboratory based gender verification test, polymerase chain reaction based testing of the SRY gene, the main candidate for male sex determination. Thus, this 'advance' in fact still fails to address the fundamental inequities of laboratory based gender verification tests. The IAAF considered the issue in 1991 and 1992, and concluded that gender verification testing was not needed. This was thought to be especially true because of the current use of urine testing to exclude doping: voiding is observed by an official in order to verify that a sample from a given athlete has actually come from his or her urethra. That males could masquerade as females in these circumstances seems extraordinarily unlikely. Screening for gender is no longer undertaken at IAAF competitions.

A regulatory cascade hypothesis for mammalian sex determination: SRY represses a negative regulator of male development

The mammalian Y chromosome carries the SRY gene, which determines testis formation. Here we review data on individuals who are XX but exhibit male characteristics: some have SRY; others do not. We have analyzed three families containing more than one such individual and show that these individuals lack SRY. Pedigree analysis leads to the hypothesis that they carry recessive mutations (in a gene termed Z) that allow expression of male characteristics. We propose that wild-type Z product is a negative regulator of male sex determination and is functional in wild-type females. In males, SRY product represses or otherwise negatively regulates Z and thereby allows male sex determination. This hypothesis can also explain other types of sex reversal in mammals, in particular, XY females containing SRY. Some of these individuals may have mutations at the Z locus rendering them insensitive to SRY. Recessive mutations (such as the polled mutation of goats) leading to sex reversal are known in a variety of animals and might be used to map and ultimately clone the human Z gene.