FG Syndrome Type 1 is a rare syndrome associated with a mutation in mediator complex subunit 12 (MED12).


Synonyms: FGS1, Opitz-Kaveggia Syndrome


Chromosome: Xq13

Gene affected: MED12 with p.Arg961Trp


Inheritance: X-linked


Clinical features:

(1) The condition affects male offspring of heterozygous female carriers.

(2) intellectual disability

(3) hypotonia

(4) constipation and/or anorectal abnormalities (imperforate anus, other)

(5) behavioral issues (attention-seeking, hyperactive, friendly)

(6) relative macrocephaly


Facial features

(1) small and simple ears

(2) prominent forehead

(3) downward slanting palpebral fissures

(4) ocular hypertelorism

(5) frontal hair upsweep


Other findings:

(1) broad thumbs and great toes

(2) abnormalities of the corpus callosum


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