Susana Kofman-Alfaro

46,XX Sex Reversal

In humans, sexual differentiation is directed by SRY, a master regulatory gene located at the Y chromosome. This gene initiates the male pathway or represses the female pathway by regulating the transcription of downstream genes; however, the precise mechanisms by which SRY acts are largely unknown. Moreover, several genes have recently been implicated in the development of the bipotential gonad even before SRY is expressed. In some individuals, the normal process of sexual differentiation is altered and a sex reversal disorder is observed. These subjects present the chromosomes of one sex but the physical attributes of the other. Over the past years, considerable progress has been achieved in the molecular characterization of these disorders by using a combination of strategies including cell biology, animal models, and by studying patients with these pathologic entities.

Male pseudohermaphroditism due to primary 5α-reductase deficiency: Variation in gender identity reversal in seven Mexican patients from five different pedigrees

In the present study, we describe the clinical, endocrinological, psychosexual and biochemical features of 7 Mexican male pseudohermaphrodites with primary 5α-reductase deficiency in whom heterogeneity in the pattern of gender identity change at puberty was observed. The patients belonged to 5 different pedigrees from diverse locations in Mexico. Six of them were admitted to the Hospital during or after puberty. The one prepubertal subject was the sibling of a previously studied patient. Basal serum gonadotropins were determined by double antibody radioimmunoassay. Basal and choriog-onadotropin (CG)-stimulated concentrations of androstenedione (A), testosterone (T) and dihydrotestosterone (DHT) were determined by radioimmunoassay after extraction and separation by celite chromatography. Urinary aetiocholanolone, androsterone and C19 and C21 5β/5α metabolite ratios were analyzed by capillary gas chromatography. Enzyme activity and androgen receptors were studied in fibroblasts cultured from genital skin. Psychological assessment was performed using the Bender-Gestalt Wechsler Adult Intelligence Scale, the Rorschach Ink Blot and the Thematic Apperception Tests. All 7 patients were unambiguously reared as females; three spontaneously changed their gender identity and role from female to male after puberty, another one changed during psychotherapy at the end of puberty. Two patients (one prepubertal and the other pubertal) have been under therapy during 1.5 years, but due to familial and social factors a female gender has prevailed. The remaining patient consulted at age 15 because of virilization; her female gender identity did not change after more than one year of treatment and due to the fact she was depressed and had suicidal tendencies, the penis and testes were removed. Immediately after starting to feminize with exogenous estrogens, she changed her gender identity and role. Baseline serum T concentrations were normal in 4 of the postpubertal cases, while 2 had low levels; DHT values were low to low normal. In all 7 cases the T/DHT (pre and/or post CG) ratio was increased while high urinary aetiocholanolone/androsterone ratios and C19 and C21 5β/5α metabolite ratios were always documented. Five subjects had decreased 5α-reductase activity in fibroblasts cultured from genital skin, whilst the remaining 2 had a normal activity. A normal amount and stability of the androgen receptor at 42C was detected in all cases. This report confirms and extends previous studies that patients with primary 5α-reductase deficiency, despite being reared as females, generally change their gender role during or after puberty due to virilization of their external genitalia and theoretically to the masculinization of the brain. The development and course of this change also depends on the subject’s personality traits, personal insight and the sociocultural factors sorrounding him.

A great diversity of Amerindian mitochondrial DNA ancestry is present in the Mexican mestizo population

There are limited data on mitochondrial DNA (mtDNA) variation in the Mexican mestizo population. To examine the genetic diversity and matrilineal ancestry, the full mtDNA hypervariable regions I and II were sequenced in 270 unrelated mestizos from different regions of Mexico. A total of 202 different haplotypes were identified and the haplotype diversity was 0.9945. Amerindian haplotypes predominated in the sample with a proportion of 93.3%, followed by European (6.0%) and African haplotypes (0.7%). The frequency of the Amerindian haplogroups A2, B2, C1 and D1 was 51.1, 17.8, 18.5 and 5.9%, respectively. The frequency of Amerindian haplogroups was higher in the central region than in Mexico City, whereas it was the contrary for European haplogroups. This difference was accounted principally by the high frequency of B2 haplotypes in the central region. The minimum spanning network, the mismatch distribution and Tajimas D neutrality test suggest a population expansion for each Amerindian haplogroup, which could be initiated more recently for haplogroups A2 and D1. The present knowledge combined with other nuclear genetic markers will be essential in future association studies to correct for genetic substructure in mestizo populations.

Participation of OCT3/4 and β-catenin during dysgenetic gonadal malignant transformation

Gonadoblastoma (GB) is an in situ tumor consisting of a heterogeneous population of mature and immature germ cells, other cells resembling immature Sertoli/granulosa cells, and Leydig/lutein-like cells, may also be present. GB almost exclusively affects a subset of patients with intersex disorders and in 30% of them overgrowth of the germinal component of the tumor is observed and the lesion is term dysgerminoma/seminoma. Several pathways have been proposed to explain the malignant process, and abnormal OCT3/4 expression is the most robust risk factor for malignant transformation. Some authors have suggested that OCT3/4 and beta-catenin might both be involved in the same oncogenic pathway, as both genes are master regulators of cell differentiation and, overexpression of either gene may result in cancer development. The mechanism by which beta-catenin participates in GB transformation is not completely clear and exploration of the E-cadherin pathway did not conclusively show that this pathway participated in the molecular pathogenesis of GB. Here we analyze seven patients with mixed gonadal dysgenesis and GB, in an effort to elucidate the participation of beta-catenin and E-cadherin, as well as OCT3/4, in the oncogenic pathways involved in the transformation of GB into seminoma/dysgerminoma. We conclude that the proliferation of immature germ cells in GB may be due to an interaction between OCT3/4 and accumulated beta-catenin in the nuclei of the immature germ cells.

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.

Novel molecular defects in the androgen receptor gene of Mexican patients with androgen insensitivity

The androgen insensitivity syndrome (AIS) is an X‐linked form of male pseudohermaphroditism caused by mutations in the androgen receptor (AR) gene. In the present study, we analyzed the AR gene in 8 patients, 4 sporadic and 2 familial cases with the syndrome, using exon‐specific polymerase chain reaction, single‐stranded conformational polymorphism and sequencing analysis and identified six new single base mutations, including one nonsense mutation at the hinge region of the receptor. These molecular lesions occurred in the steroid‐binding domain (SBD) and all but one affected the first nucleotide of their respective codons. A nonsense mutation in exon 4, which converts a glutamine into a premature termination signal (Q657stop), a missense mutation changing arginine instead of glycine (G743R) and a conservative substitution of leucine with valine at amino acid 830 (L830V) were detected in patients with CAIS. Three other missense mutations located in exons 4 (L701I), 5 (A765S), and 6 (Q802R) were present in individuals bearing a partial form of AIS. These data allow us to reaffirm the view that nonsense mutations in the AR results almost invariably in a CAIS phenotype and underly the importance of the SBD for the AR functional activity.

Acrodysostosis in two generations: an autosomal dominant syndrome.

Acrodysostosis is a rare syndrome characterized by growth retardation, peripheral dysostosis and mental deficiency. X‐rays reveal generalized shortening of metacarpals, metatarsals and phalanges, hyperplasia of the first ray of the feet and premature skeletal maturation. Occasionally abnormal interpedicular spinal spaces, increased mandibular angle and hearing loss have been observed. We report a 19‐year‐old woman and her daughter examined at birth and subsequently at 6 years of age. The clinical and radiological characteristics are those of acrodysostosis. The syndrome is easily recognized at birth. The generalized corporal shortening is progressive and could be due to premature closing of epiphyses. The finding of an affected mother and her daughter support the postulate that acrodysostosis is inherited as an autosomal dominant syndrome.

Community Genetic Services in Latin America and Regional Network of Medical Genetics

The World Health Organization sponsored a Consultation on Community Genetic Services and a Regional Network of Medical Genetics in Latin America in Porto Alegre, Brazil, on June 19, 2003. The main recommendations of the meeting included: (a) the call for government funding of services, research and education in medical genetics; (b) the conduct of epidemiological research on the prevalence and types of birth defects, genetic disorders and genetic predispositions to common diseases; (c) the education of health professionals in genetics; (d) the education of genetic professionals in community health and public health genetics; (e) the fostering of interactions between clinical geneticists, public health personnel, primary health care workers and community organizations, and (f) a better planning of regionalized services to avoid duplication and inefficiency.

Congenital heart defect and conductive hypoacusia in a patient with the KBG syndrome

1977, Fryns et al. 1984, Soekarman et al. 1994). Recently, we had a patient with features compatible with the KBG syndrome. In addition, he presented stenosis of the left pulmonary artery and conductive bilateral hypoacusia. These findings have not previously been associated with this entity. Our patient was a 15-year-old male, born as the second of four children, after an uncomplicated pregnancy. Delivery was normal. His parents were consanguineous in the second degree. Clinical examination revealed short stature (117 cm), low weight (23 kg), mental retardation, brachycephaly, prominent forehead with low-set hair line, triangular face, synophrys, epicanthus with inner canthal distance 32 mm (50th centile) and outer canthal distance 95 m (75-97th centile), hypertelorism, lowset ears, broad nose with anteverted narines, large philtrum and micrognathia (Fig. 1). Macro-oligodontia and incisor-canine diastasis were observed (Fig. 2). Both hands showed transversal palmar

Unusual mixed gonadal dysgenesis associated with Müllerian duct persistence, polygonadia, and a 45,X/46,X,idic(Y)(p) karyotype

Mixed gonadal dysgenesis (MGD) is a developmental anomaly in which most of the patients have a dysgenetic testis, a contralateral streak and a 45,X/46,XY karyotype. This entity involves an heterogeneous group of gonadal and phenotypic abnormalities with a wide clinical spectrum. The phenotype depends on the ratio of testicular tissue which induces virilization. Although the karyotype in these patients is 45,X/46,XY, no genotype–phenotype correlation has been found to date. Müllerian ducts persistence (MDP) in MGD is rare; however, four patients with both entities and different karyotypes have been described. Here we present the data on a newborn patient with an atypical MGD associated with MDP, two left testes, a gonadal streak on the right, and absence of Wolffian derivatives. PCR analysis identified all the Y‐derived sequence tested in the father, while the patient had them all except the AZF b,c regions which were lost. FISH analysis of the paternal Y chromosome documented Yq paracentric inversion while the patients karyotype was 45,X/46,X,idic(Yp). No mutations were observed in MIS/MISRII genes.