Nonsense mutations FERMT3, encoding kindlin-3, result in the LAD1v syndrome. (A) A homozygous c.1525 C>T mutation in exon 12 results in p.Arg509X in patients from the previously described families 1 to 7, and a homozygous c.1717 C>T mutation in exon 14 yields p.Arg573X in family 8. Y and R refer to base position mixtures of C/T and G/A, respectively.(B) Heterozygotes show preferential presence of normal transcripts over mutated FERMT3 transcripts, as shown for families 1 to 7. (C) Irrespective of the mutation, the protein kindlin-3 is undetectable at the expected relative molecular mass of 76 kDa in the platelets of LAD1v patients (and leukocytes, data not shown); the 25-kDa control protein glyceraldehyde-3-phosphate dehydrogenase was observed in all lanes serving as loading control.