SYT1-associated neurodevelopmental disorder explained

SYT1-associated neurodevelopmental disorder
Synonyms:	Baker-Gordon syndrome
Field:	Medical genetics, neurology

SYT1-associated neurodevelopmental disorder, also known as Baker-Gordon syndrome, is a rare genetic disorder caused by mutations in the synaptotagmin-1 (SYT1) gene.^[1]

Signs and symptoms

Patients present with neurodevelomental impairments and symptoms including:

• Infantile hypotonia
• Congenital ophthalmic abnormalities
• Childhood onset hyperkinetic movement disorder
• Stereotypical motor behaviour
• Moderate to profound developmental delay or intellectual disability
• Sleep disturbance
• Episodic agitation

Epileptic seizures are not a feature of this disorder (despite abnormal EEG) and head circumference is typically normal.

Genetics

This condition is caused by heterozygous mutations in the SYT1 gene, located on the long arm of chromosome 12 (12q21.2), which are inherited in an autosomal dominant fashion.

Pathogenesis

Synaptotagmin-1 is a predominantly presynaptic Ca²⁺-sensor involved in synaptic vesicle exocytosis and endocytosis. In SYT1-associated neurodevelopmental disorder, mutations disrupt synaptotagmin-1 function causing a reduction in neurotransmitter release.^[1]

Diagnosis

This disorder may be suspected on the basis of the clinical features listed above and abnormal EEG recording. Diagnosis is made through genetic testing with sequencing of the SYT1 gene.

Management

At present, only supportive management of symptoms is available as there is no known curative treatment for this condition.

History

The first case of SYT1-associated neurodevelopmental disorder was described in 2015^[2] and it was classified as a syndrome in 2018.^{[1] [3]} It was named after Sarah Gordon and Kate Baker, who first discovered and described it.^[1]

Notes and References

1. Baker K, Gordon SL, Melland H, Bumbak F, Scott DJ, Jiang TJ, Owen D, Turner BJ, Boyd SG, Rossi M, Al-Raqad M, Elpeleg O, Peck D, Mancini GM, Wilke M, Zollino M, Marangi G, Weigand H, Borggraefe I, Haack T, Stark Z, Sadedin S, Tan TY, Jiang Y, Gibbs RA, Ellingwood S, Amaral M, Kelley W, Kurian MA, Cousin MA, Raymond FL . 6 . SYT1-associated neurodevelopmental disorder: a case series . Brain . 141 . 9 . 2576–2591 . September 2018 . 30107533 . 6113648 . 10.1093/brain/awy209 . free .
2. Baker K, Gordon SL, Grozeva D, van Kogelenberg M, Roberts NY, Pike M, Blair E, Hurles ME, Chong WK, Baldeweg T, Kurian MA, Boyd SG, Cousin MA, Raymond FL . 6 . Identification of a human synaptotagmin-1 mutation that perturbs synaptic vesicle cycling . The Journal of Clinical Investigation . 125 . 4 . 1670–8 . April 2015 . 25705886 . 4396464 . 10.1172/JCI79765 . free .
3. Web site: OMIM entry: Baker-Gordon Syndrome .