(A) Pedigree diagram showing all four investigated nuclear families (families 1–4), which interlink into a single extended family. Segregation of the two mutations identified (c.776C>A [p.Ser259∗] is denoted by X, and c.714_731dup [p.Met241_Gln246dup] is denoted by Dup) is shown (all genotypings were validated by dideoxy sequence analysis).