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At a glance

It is a medical condition characterized by severe mental retardation affecting mostly males. It is associated with childhood-onset obesity. The phenotype is variable, combining gynecomastia, obesity, speech disability, hypogonadism, short stature, and small hands/feet.

Synonyms

X-Linked Mental Retardation Syndromic 6; X-Linked Mental Retardation Gynecomastia Obesity Syndrome; Mental Retardation X-Linked Gynecomastia Obesity Syndrome.

History

The first report of a family affected with mental retardation linked to an X-linked inheritance was in 1943 by Martin and Bell. However, it is only in 1991 that it was recognized as a separate entity when Wilson studied 14 males from three successive generations that presented hypogonadism, mental retardation, gynecomastia, short stature, and short hands/feet.

Incidence

The exact incidence remains unknown.

Genetic inheritance

It is a very rare syndrome affecting mostly males in the complete form. Females have generally a milder phenotype. It is believed to be inherited as an X-linked recessive inheritance trait and it is the result of a mutation in the HDAC8 gene, located on the q arm of chromosome 13.1.

Pathophysiology

It is believed that Wilson-Turner Syndrome (WTS) results from a underdeveloped histone deacetylase 8 and enzyme coded on the HDAC8 gene. Histone deacetylase 8 seems to regulate and stabilize the cell’s genetic information, repairing damaged DNA, and controlling gene activity. Males present increased plasmatic estrogen and androgen hormones than normal. Hypogonadism and gynecomastia result from this endocrine abnormality. Most of the facial deformities caused by the HDAC8 mutation include prominent supraorbital ridges and high cheekbones. Researchers have also linked the HDAC8 gene to obesity.

Diagnosis

The most notable features are mental disability, severe childhood obesity, hypogonadism, gynecomastia, and distinct facial features. The diagnosis is based upon a clinical evaluation, and molecular genetic testing for mutations in the HDAC8 gene. In order to be diagnosed with Wilson-Turner Syndrome, affected males must have mild to moderate intellectual disability, childhood obesity, short hands/feet, gynecomastia, and hypogonadism. Affected females have less severe clinical manifestations than males. It is reported that female carriers have none or mild symptoms.

Clinical aspects

Probable developmental anomaly of the central nervous system, dysfunction of the hypothalamic pituitary-gonadal axis, with secondary rather than primary gonadal insufficiency. Principal features are mental retardation, obesity, gynecomastia, speech difficulties, emotional lability, tapering fingers, and small feet. Many other signs have been occasionally described.

Precautions before anesthesia

For elective surgical procedures, it is highly recommended to obtain a consultation in endocrinology. The potential association between obesity and Type 2 diabetes must be considered. Also, the presence of facial features that may impact on the management of the airway is important.

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