Parents

Prevalence
So far, only 3 unrelated patients with an heterozygous mutation truncating the LAMB1 protein have been reported in the medical literature. Nevertheless, more individuals will likely be found now that the MRI/clinical picture and the responsible mutations have been reported.

Main clinical features and inheritance
Heterozygous pathogenic variants in the LAMB1 gene (only one of the 2 LAMB1 alleles is mutated) cause episodic memory dysfunction starting around 60 years old and diffuse white matter hypersignals on cerebral MRI. The disease is inherited as an autosomal dominant manner but the penetrance is unknown (percentage of individuals who carry the mutation who will develop the disease).

Diagnosis
LAMB1 variants can be identified using molecular genetic testing, either by either direct sequencing of the LAMB1 gene or exome/genome sequencing.