Challenges in clinical and laboratory diagnosis of androgen insensitivity syndrome: a case report

<p>Abstract</p> <p>Introduction</p> <p>Androgen is a generic term usually applied to describe a group of sex steroid hormones. Androgens are responsible for male sex differentiation during embryogenesis at the sixth or seventh week of gestation, triggering the development of the testes and penis in male fetuses, and are directed by the testicular determining factor: the gene <it>SRY </it>(sex determining region on Y chromosome) located on the short arm of chromosome Y. The differentiation of male external genitalia (penis, scrotum and penile urethra) occurs between the 9th and 13th weeks of pregnancy and requires adequate concentration of testosterone and the conversion of this to another more potent androgen, dihydrotestosterone, through the action of 5α-reductase in target tissues.</p> <p>Case presentation</p> <p>This report describes the case of a teenage girl presenting with a male karyotype, and aims to determine the extension of the mutation that affected the AR gene. A Caucasian girl aged 15 was referred to our laboratory for genetic testing due to primary amenorrhea. Physical examination, karyotype testing and molecular analysis of the androgen receptor were critical in making the correct diagnosis of complete androgen insensitivity syndrome.</p> <p>Conclusions</p> <p>Sex determination and differentiation depend on a cascade of events that begins with the establishment of chromosomal sex at fertilization and ends with sexual maturation at puberty, subsequently leading to fertility. Mutations affecting the <it>AR </it>gene may cause either complete or partial androgen insensitivity syndrome. The case reported here is consistent with complete androgen insensitivity syndrome, misdiagnosed at birth, and consequently our patient was raised both socially and educationally as a female. It is critical that health care providers understand the importance of properly diagnosing a newborn manifesting ambiguous genitalia. Furthermore, a child with a pseudohermaphrodite phenotype should always undergo adequate endocrine and genetic testing to reach a conclusive diagnosis before gender is assigned and surgical interventions are carried out. Our results show that extreme care must be taken in selecting the genetic tools that are utilized for the diagnosis for androgen insensitivity syndrome.</p

Banded karyotype of Nelore cattle (Bos taurus indicus Linnaeus, 1758)

Chromosome banding techniques were applied and standardized to obtain karyotype characteristics for the first time in Brazil of Nelore cattle – Bos taurus indicus Linnaeus, 1758 – (bovine subspecies most prominent in Brazilian livestock). Blood samples were collected from the animals of the School of Agrarian and Biological Sciences of the Pontifical Catholic University of Goiás, two males and two females of pure breed. These samples were submitted to the cell culture method to study metaphase chromosomes. Chromosome banding techniques (C, G and NOR) revealed the karyotype architecture of Nelore cattle common with that of other breeds of zebu cattle formerly karyotyped. The diploid chromosome number was invariably normal, 2n = 60. C-banding revealed C-positive heterochromatin in centromeric regions almost in all chromosomes. G-banding presented the expected band pattern in the respective chromosome pairs in correspondence with the established chromosomal patterns for the species. Ag-staining for nucleolus organizer regions (AgNOR) was identified on the telomeric end of the long arm in 7 autosomal chromosomes. In this study we found more regions in chromosomes with staining than presented in the literature for the Bos indicus group (BIN). These NOR regions were repeated on the same chromosomes for the 4 animals studied

Morphometric and genetic differentiation among populations of Eupemphix nattereri (Amphibia, Anura, Leiuperidae) from central Brazil

To assess genetic structure and phenotypic diversity of Eupemphix nattereri Steindachner, 1863, morphometric and molecular analyses were carried out for nine populations from the State of Goiás. A total of 11 morphometric traits were evaluated and genetic information was estimated using RAPD markers. Genetic and phenotypic distances were determined as a function of geographical origin. Correlation among genetic, morphometric, micro, and macroenviromental were analyzed by the Mantel test. Genetic data indicated high levels of genetic diversity (&#934;st= 0.3) among the nine populations. Mantel tests did not reveal a significant positive correlation between genetic and geographical distances, indicating that locally geographical populations were not genetically similar, even in distances smaller than 50 km. Discriminant analysis on 11 morphometric measurements showed a high divergence among the nine populations. However, a marginally significant correlation (P=0.08) between genetic and morphometric distances was found. The observed correlation was not causal in terms of the relationship between phenotype and genotype, but indicated common spatial structures. Thus, our results suggest that isolation-by-distance processes may explain population divergence in Eupemphix nattereri