Single Faulty Gene Causes Males to Develop as Females

Kathleen Blanchard's picture
The MAP3K1
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Researchers from the University of Melbourne have discovered a single faulty gene that causes some male embryos to develop as females, otherwise known as disorders of sexual development (DSD). The gene alteration leading to was discovered by the researchers in a group of patients that included two families with several members possessing the faulty gene.

According to study information, one in 4500 babies are born with "ambiguous genitalia". The NIH, describes characteristics that include small penis and scrotum that may look like labia, undescended testicles and urethral opening along, below or above the penis that also leads to the appearance of a female infant that actually has male chromosomes.

MAP3K1 gene singled out as cause of disorders of sex development

Andrew Sinclair, lead researcher from the University of Melbourne and Murdoch Childrens Research Institute said it is the MAP3K1 gene that becomes faulty, disrupting normal development of testicles.

β€œTo date, we know of only a small number of genes that are involved in gonad development, and can only diagnose about 20 per cent of DSD patients,” he said.

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Based on our study, we believe mutation of the MAP3K1 gene could be responsible for a further 20 per cent ...cases. This is a major breakthrough as the MAP3K1 gene provides new insights into normal testis development and significantly increases the number of DSD cases we can diagnose in the future.”

The gene disruption results in a male XY chromosome baby with female characteristics. Normally, females have two X chromosomes and males have an X and a Y. When the MAP3K1 gene becomes faulty, the infant is still a male, but has feminine characteristics.

Professor Sinclair explains DSD is a source of anxiety for parents and clinicians. Infants who would normally be born male but have ambiguous genitalia are at risk for physical and emotional health problems that includes cancer of the testicles.

Sinclair says understanding how a single faulty gene causes male embryos with XY chromosomes to develop more like females can help clinicians manage patients and provides comfort and understanding to those affected.

University of Melbourne

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