FLNA p.V528M substitution is neither associated with bilateral periventricular nodular heterotopia nor with macrothrombocytopenia

Filamin A is encoded by the FLNA gene on chromosome Xq28 and functions in cross-linking actin filaments into orthogonal networks in the cortical cytoplasm. FLNA p.V528M was initially detected in a female autopsy case of X-linked bilateral periventricular nodular heterotopia (BPNH), a neuronal migration disorder characterized by subependymal nodules of gray matter. During our mutation analysis of FLNA in a boy with apparent X-linked thrombocytopenia, we detected the p.V528M variant. The patient, mother and sister, who were heterozygous for the substitution, did not have BPNH. We observed an allele frequency of 4.8% in healthy control Japanese, but did not observe the variant in Caucasian subjects. Hemizygous controls had a normal platelet count and size. We suggest that p. V528M is neither associated with BPNH nor with thrombocytopenia and giant platelets, and represents a functional polymorphism. Journal of Human Genetics (2010) 55, 844-846; doi:10.1038/jhg.2010.114; published online 16 September 2010