Figure 2. Family Trees Demonstrating Examples of the Various Types of FIPA Families. In some AIP mutation-negative FIPA families unaffected obligate carriers can be identified by their position in the family tree, while in other family’s possible carriers of the unidentified gene cannot be identified. AIP mutation-positive kindreds can be ‘families’ or simplex cases. Most XLAG kindreds are simplex cases with females having de novo germline mutations while males have somatic mosaic mutations.