Genotype-phenotype correlations and putative modifier genes in SYNGAP1 Encephalopathy

Area of Science:

• Neuroscience
• Genetics
• Developmental Biology

Background:

• Synaptic Ras GTPase-Activating Protein 1 (SynGAP), encoded by the SYNGAP1 gene, is crucial for synaptic plasticity, neurodevelopment, and neuronal function.
• Pathogenic variants in SYNGAP1 cause SYNGAP1 Encephalopathy, a neurodevelopmental disorder with variable symptoms including intellectual disability, epilepsy, and autistic traits.
• Current understanding of genotype-phenotype correlations in SYNGAP1 Encephalopathy is limited, hindering personalized treatment strategies.

Purpose of the Study:

• To investigate the impact of SYNGAP1 gene variants and potential genetic modifiers on the clinical features of SYNGAP1 Encephalopathy.
• To identify novel pathogenic SYNGAP1 variants associated with the disorder.
• To explore how variant location and additional genetic factors contribute to phenotypic heterogeneity.

Main Methods:

• Analysis of a cohort of 44 extensively phenotyped cases with SYNGAP1 Encephalopathy.
• Genetic analysis to identify variants in SYNGAP1 and related genes.
• Correlation of genetic findings with detailed clinical characteristics.

Main Results:

• Identification of four previously unreported likely pathogenic SYNGAP1 variants.
• Patients with variants in the SynGAP PH domain showed milder phenotypes compared to others.
• Individuals with rare or low-frequency variants in SYNGAP1-related genes exhibited greater global disease severity.

Conclusions:

• The location of SYNGAP1 variants plays a role in determining the clinical presentation of SYNGAP1 Encephalopathy.
• Additional genetic modifiers likely contribute to the variability in disease severity and clinical manifestations.
• Further research with larger cohorts and functional studies is necessary to refine genotype-phenotype correlations and develop personalized management approaches.