BackgroundDisorders of sex development (DSD) are congenital conditions in which chromosomal, gonadal, or phenotypic sex is atypical. Clinical management of DSD is often difficult and currently only 13% of patients receive an accurate clinical genetic diagnosis. To address this we have developed a massively parallel sequencing targeted DSD gene panel which allows us to sequence all 64 known diagnostic DSD genes and candidate genes simultaneously.ResultsWe analyzed DNA from the largest reported international cohort of patients with DSD (278 patients with 46,XY DSD and 48 with 46,XX DSD). Our targeted gene panel compares favorably with other sequencing platforms. We found a total of 28 diagnostic genes that are implicated in DSD, highlighting the genetic spectrum of this disorder. Sequencing revealed 93 previously unreported DSD gene variants. Overall, we identified a likely genetic diagnosis in 43% of patients with 46,XY DSD. In patients with 46,XY disorders of androgen synthesis and action the genetic diagnosis rate reached 60%. Surprisingly, little difference in diagnostic rate was observed between singletons and trios. In many cases our findings are informative as to the likely cause of the DSD, which will facilitate clinical management.ConclusionsOur massively parallel sequencing targeted DSD gene panel represents an economical means of improving the genetic diagnostic capability for patients affected by DSD. Implementation of this panel in a large cohort of patients has expanded our understanding of the underlying genetic etiology of DSD. The inclusion of research candidate genes also provides an invaluable resource for future identification of novel genes.Electronic supplementary materialThe online version of this article (doi:10.1186/s13059-016-1105-y) contains supplementary material, which is available to authorized users.
These patients define a new disorder, nonclassic lipoid congenital adrenal hyperplasia, and represent a new cause of nonautoimmune Addison disease (primary adrenal failure).
These studies demonstrate that aromatase mutations can produce variable or "nonclassic" phenotypes in humans. Low residual aromatase activity may be sufficient for breast and uterine development to occur at puberty, despite significant androgenization in utero. Such phenotypic variability may be influenced further by modifying factors such as nonclassic pathways of estrogen synthesis, variability in coregulators, or differences in androgen responsiveness.
We implicate FGF8 in the etiology of recessive HPE and potentially septo-optic dysplasia/Moebius syndrome for the first time to our knowledge. Furthermore, FGF8 is important for the development of the ventral diencephalon, hypothalamus, and pituitary.
IGHD patients with severe growth failure and a positive family history should be screened for genetic mutations; the evolving endocrinopathy observed in some of these patients suggests the need for long-term follow-up.
PROP1 mutations are rare in sporadic cases of CPHD, although the prevalence rises if there is a positive family history or if the patients are carefully selected with respect to the endocrine and neuroradiological phenotype. There is considerable phenotypic variability in families with the same mutation, indicating the role of other genetic or environmental factors on phenotypic expression. Finally, the pituitary enlargement that is observed in patients with PROP1 mutations can wax and wane in size before eventual involution.
The way disorders of sex development (DSD) are viewed and managed in different cultures varies widely. They are complex conditions and even well-educated lay people find them difficult to understand, but when families are very poor and lacking in basic education, and the health system is starved of resources, traditional beliefs, folk remedies and prejudice combine to make the lives of children and adults with DSD extremely difficult and sad. Rumour and discrimination isolate them from their communities and they become devalued. People with DSDs desire the same things in life as everyone else-to find someone who will love them, to be valued as human beings, to feel at home in their own bodies, to be able to have satisfactory sexual relations should these be desired, to be able to trust their medical advisers and to be integrated into the general community. Long term outcome studies have been published from many countries, but these studies have not necessarily been critical of the values that underpinned the type of treatment given to the patients. There is a need for standardized instruments that would allow a true comparison of the quality of outcomes from the patients' perspective. Much could be done to improve equity between rich and poor countries for the benefit of people with DSDs. A focus on developing cheap, robust diagnostic tests, making essential medicines available for all, training surgeons to do better operations, educating health professionals, families and the general community in order to break down prejudice against people with DSDs, and training mental health workers in this specialized field, would do much to alleviate the burden of the condition.
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