Syt1, also known as Synaptotagmin-1, is a well-known calcium sensor. It plays a crucial role in mediating the release of calcium-triggered neurotransmitters during regular synaptic vesicle exocytosis, which is essential for synaptic neurotransmission [1,3]. It is also involved in processes like migrasome formation [2]. Dysfunction of Syt1 can lead to severe neurological impairment, and genetic variants are associated with SYT1-associated neurodevelopmental disorder [1].

In a study of SYT1-associated neurodevelopmental disorder, 11 patients with de novo heterozygous missense mutations in SYT1 were described. These mutations affected highly conserved residues in the SYT1 C2B domain. Phenotypic features included infantile hypotonia, congenital ophthalmic abnormalities, and childhood-onset hyperkinetic movement disorders. Functional impact assessment in wild-type mouse primary hippocampal cultures showed that mutant forms of SYT1 had various effects on neurotransmitter release kinetics, with the severity of the affected individuals' phenotypes mirroring the disturbance to synaptic vesicle kinetics [3]. Another study reported a 21-year-old woman with a novel SYT1 gene variant presenting a complex phenotype including severe intellectual disability, epilepsy, and motor stereotypies, expanding the known SYT1-related clinical phenotype [4]. STON2 variations, which affect its interaction with Syt1, lead to deficits in synaptic transmission and schizophrenia-like behaviors in knockin mice, suggesting Syt1's role in synaptic function related to schizophrenia [5].

In conclusion, Syt1 is essential for synaptic neurotransmission and other biological processes. Studies using models such as patient cases and knockin mice have revealed its significant role in SYT1-associated neurodevelopmental disorder and in synaptic dysfunction related to schizophrenia, providing insights into the underlying mechanisms of these diseases.