To date, only ten individuals with GLYT1 encephalopathy from five unrelated families have been described in the literature, and all of them present two mutations in the SLC6A9 gene (autosomal recessive inheritance pattern). In all cases, parents were consanguineous.
The pathophysiologic mechanism of the disorder is loss of GLYT1 transporter function (or a severely diminished activity), which leads to high levels of the amino acid glycine in the synapses of the brain. This results in abnormal neurotransmitter signaling, which explains the clinical manifestations of the disease.
The molecular diagnosis of GLYT1 encephalopathy is established in a proband by identification of two mutations in the gene SLC6A9 by genetic testing.
SLC6A9