IFIH1 and Aicardi-Goutieres syndrome: Moreover, clinical non-penetrance is an established feature of certain AGS genotypes (in particular, a study of patients with autosomal dominant MDA5 (melanoma differentiation associated protein 5)-associated disease identified 13.5% (10 of 74) of all defined mutation carriers, to be clinically asymptomatic – with seven of these individuals aged greater than 50 years (54)).