Mental Retardation, X-Linked, Syndromic 33

What is Mental Retardation, X-Linked, Syndromic 33?

It is a rare genetic syndrome and neurodevelopmental disorder characterized by intellectual disability and psychomotor delay. The syndrome, due to the way in which it is inherited, is most severe in males.

What gene changes cause Mental Retardation, X-Linked, Syndromic 33?

Changes to the TAF1 gene are responsible for causing the syndrome. This is also linked to dystonia-parkinsonism syndrome. It is inherited in an X-linked recessive pattern.

Syndromes inherited in an X-linked recessive pattern generally only affect males. Males only have one X chromosome, and so one copy of a gene mutation on it causes the syndrome. Females, with two X chromosomes, only one of which will be mutated, are not likely to be affected.

What are the main symptoms of Mental Retardation, X-Linked, Syndromic 33?

Intellectual disability and global developmental delay affecting all areas of development are main symptoms of the syndrome. Some individuals are diagnosed with autistic features.

Growth delay, both before and after birth, is another main symptom.

Unique facial features of the syndrome include a small head, low set and protruding ears, a long face, a pointed chin and sagging cheeks. Individuals also suffer from recurrent ear infections and in some cases hearing loss too.

How does someone get tested for Mental Retardation, X-Linked, Syndromic 33?

The initial testing for Mental Retardation, X-Linked, Syndromic 33 can begin with facial analysis screening, through the FDNA Telehealth telegenetics platform, which can identify the key markers of the syndrome and outline the need for further testing. A consultation with a genetic counselor and then a geneticist will follow.

Based on this clinical consultation with a geneticist, the different options for genetic testing will be shared and consent will be sought for further testing.

Medical information on Mental Retardation, X-Linked, Syndromic 33

O'Rawe et al., (2015) reported a cohort of males including male sibs, with intellectual problems and facial dysmorphism. They had prominent ears and supraorbital ridges, a long philtrum, down-slanting fissures, a long face, sagging cheeks and pointed chin. In some, there were dystonic features and in some the features were progressive. There were 2 cases with TAF1 duplications who facially were milder, but had progressive neurological signs.
In a cohort of 405 families with X linked intellectual disability, Hu et. al. (2016) found six male patients with two families with missense mutations in the TAF1 gene. Intellectual disability was accompanied with spastic paraplegia in one family and dysmorphic features in the other.
Fifty six families with West syndrome were analyzed by Peng et. al. (2018). Two families with missense mutations in the TAF1 gene (inherited from the mother) were identified.

* This information is courtesy of the L M D.
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