Turner syndrome and sexual differentiation of the brain: implications for understanding male-biased neurodevelopmental disorders

Turner syndrome (TS) is one of the most common sex chromosome abnormalities. Affected individuals often show a unique pattern of cognitive strengths and weaknesses and are at increased risk for a number of other neurodevelopmental conditions, many of which are more common in typical males than typical females (e.g., autism and attention-deficit hyperactivity disorder). This phenotype may reflect gonadal steroid deficiency, haploinsufficiency of X chromosome genes, failure to express parentally imprinted genes, and the uncovering of X chromosome mutations. Understanding the contribution of these different mechanisms to outcome has the potential to improve clinical care for individuals with TS and to better our understanding of the differential vulnerability to and expression of neurodevelopmental disorders in males and females. In this paper, we review what is currently known about cognition and brain development in individuals with TS, discuss underlying mechanisms and their relevance to understanding male-biased neurodevelopmental conditions, and suggest directions for future research

Disorders of sex development: effect of molecular diagnostics

Disorders of sex development (DSDs) are a diverse group of conditions that can be challenging to diagnose accurately using standard phenotypic and biochemical approaches. Obtaining a specific diagnosis can be important for identifying potentially life-threatening associated disorders, as well as providing information to guide parents in deciding on the most appropriate management for their child. Within the past 5 years, advances in molecular methodologies have helped to identify several novel causes of DSDs; molecular tests to aid diagnosis and genetic counselling have now been adopted into clinical practice. Occasionally, genetic profiling of embryos prior to implantation as an adjunct to assisted reproduction, prenatal diagnosis of at-risk pregnancies and confirmatory testing of positive results found during newborn biochemical screening are performed. Of the available genetic tests, the candidate gene approach is the most popular. New high-throughput DNA analysis could enable a genetic diagnosis to be made when the aetiology is unknown or many differential diagnoses are possible. Nonetheless, concerns exist about the use of genetic tests. For instance, a diagnosis is not always possible even using new molecular approaches (which can be worrying for the parents) and incidental information obtained during the test might cause anxiety. Careful selection of the genetic test indicated for each condition remains important for good clinical practice. The purpose of this Review is to describe advances in molecular biological techniques for diagnosing DSDs

A del(X)(p11) carrying SRY sequences in an infant with ambiguous genitalia

BACKGROUND: SRY (sex-determining region, Y) is the gene responsible of gonadal differentiation in the male and it is essential for the regular development of male genitalia. Translocations involving the human sex chromosomes are rarely reported, however here we are reporting a very rare translocation of SRY gene to the q -arm of a deleted X chromosome. This finding was confirmed by cytogenetic, fluorescent in situ hybridization (FISH) and polymerase chain reaction (PCR). CASE PRESENTATION: A 7-month infant was clinically diagnosed as an intersex case, with a phallus, labia majora and minora, a blind vagina and a male urethra. Neither uterus nor testes was detected by Ultrasonography. G-banding of his chromosomes showed 46,X,del(X)(p11) and fluorescent in situ hybridization (FISH) analysis showed a very small piece from the Y chromosome translocated to the q-arm of the del(X). Polymerase chain reaction (PCR) analysis revealed the presence of material from the sex-determining region Y (SRY) gene. CONCLUSION: It is suggested that the phenotype of the patient was caused by activation of the deleted X chromosome with SRY translocation, which is responsible for gonadal differentiation