Fig. 1

Family pedigree

Blackened squares, affected males; diagonal slash, deceased; open symbols, unaffected; circle with a black central point, obligate carriers; circle with a question mark, a female of unknown carrier status. Individual identification numbers are indicated at the upper left of the symbol(s). Age is in years (y.) or months (m.), at present or at time of death. Generation is indicated to the right with a Roman numeral. Dashed vertical line indicate that there are additional family members who are not informative. Proband (II-2) is designated by an arrow.