ClinVar

Description

The p.Arg484Gln variant in FLNA has been reported in two Turkish brothers (age of onset: 16 and 11; with healthy parents and grandparents) with occipital lobe epilepsy and epileptic status in sleep. They are diagnosed as periventricular nodular heterotopia (PVNH), which is a cell migration disorder. Heterozygous mother is asymptomatic, and healthy father carries the reference allele. Generally, heterozygous females carrying PVNH-related missense mutations have mild or no symptoms as in the mother. This is the reason of the presence of this variant (rs782371735) in the population databases (e.g. ExAC 0.009%). On the other hand, only a few males (<40) can survive, and they should have compensating mechanisms for the function of FLNA. Therefore, we investigated the etiology of the disease by observing the impact of PVNH-related FLNA mutations found in the liveborn males on the structure and dynamics of FLNA protein via molecular dynamics (MD) simulations. For the p.Arg484Gln variant, MD studies showed that the mutation does not lead to a general misfolding or permanent loss of function. Instead, it may cause a temporary dysfunction since we observed significant changes in the fluctuations (higher), solvent-accessible surface area (lower), conformational space and local interactions (i.e. H-bonds and salt bridges within 10 Ã… of the mutation site) in the half of the MD simulations. This event might lead to formation of nodules in the periventricular region and might also compensate the cell migration function. Thus, the males who have this variant can survive with the only copy of mutated FLNA.