Further delineate the clinical and molecular spectrum of recessive pathogenic SLC6A9 variants

Targeted gene/genes/phenotype under study : SLC6A9

Abstract :

Up to date 6 patients have been reported with recessive pathogenic SLC6A9 variants, responsible for Glycine transporter 1 encephalopathy (OMIM# 617301; glycine encephalopathy with normal serum glycine, GLYT1 transporter dysfunction, and nonketotic hyperglycinemia). Patients present with neonatal respiratory failure, inital hypotonia followed by limb hypertonia, severe developmental delay, arthrogryposis, startle like responses to noise or tactile stimulation and similar dysmorphic features. CSF levels of glycine are mildly elevated in these patients, whereas serum glycine levels are normal.

We have recently identified 3 novel patients from 2 unrelated families with pathogenic SLC6A9 recessive variants and consistent phenotype. With the help of GeneDx, another patient has been identified. We aim to find more families to collect clinical and molecular data, pictures, cerebral imaging, biochemical results, in order to publish a new series of patients to further delineate this genetic disease.

Coordinating clinician : Dr Sandra Whalen

Institution :

Clinical Genetics Department

Armand Trousseau Hospital – APHP

26 Avenue du Dr Arnold Netter, 75012 Paris


Contact : sandra.whalen@aphp.fr

Specific requirements beyond clinical data and genotype data sharing:

  • Re-analysis of DNA samples Y/N : N
  • Resampling of patients Y/N : N
  • Linked to a transnational /basic research project? Y/N : N