Novel in cis double MPL mutation is associated with familial CAMT type I. (A) Pedigree tree that illustrates the autosomal recessive transmission pattern in this family. Circles represent females and squares represent males. Open symbols indicate healthy family members, filled symbols indicate family members with CAMT type I, single horizontal line connecting 2 symbols indicates monozygotic twins, and slashes represent deceased family members. The genotypes of all family members are presented as genomic DNA sequencing chromatograms. Family members I.1, I.2, and II.1 are heterozygous for the 2 G117T mutation in exon 2 and the T814C mutation in exon 5. Family members II.2, II.3, and II.4 are homozygous for both mutations. (B) Schematic representation of the functional domains of the Tpo receptor and the location of extracellular G117T (K39N) polymorphism and T814C (W272R) mutation. C, cysteine residue; FN III, fibronectin III domain; SP, signal peptide; TM, transmembrane domain; Tyr, tyrosine residue.