Genetic testing
Variants in GNB1 can be identified using molecular genetic testing, either directly by sequencing of the GNB1 gene or by exome/genome sequencing.
Molecular characteristics
Most variants that have been detected in the GNB1 gene have been missense variants, however, frameshift and splice site variants have also been reported (GenBank: NM_002074.4). Most variants cluster in exons 5 and 6 of the gene, which are part of the sequence relevant for the interaction between Gα and Gβγ in the G protein complex. The most observed substitution affects the p.Ile80 residue encoded in exon 6, with 28% of reported affected individuals carrying a variant at this residue. Other recurrent variants include p.Leu95Pro, p.Asp118Gly, and and p.Lys78Arg. and M101V?
Genotype- Phenotype correlations
Dystonia and growth delay were observed more frequently in patients carrying variants in the p.Ile80 residue, suggesting a potential genotype-phenotype correlation.