Pedigree, thyroid function tests results, and mutations identified in family 1 (A) and family 2 (B). Generations are indicated with Roman numerals, and individuals with Arabic numbers above each symbol. Laboratory data are aligned below each symbol. Vertical shading of symbols indicates heterozygous for the mutation and horizontal shading of the symbols indicates homozygosity for the mutation. Abnormal values are in bold type. LT4, levothyroxine; TT4, total thyroxine; TT3, total triiodothyronine; fT4, free thyroxine; TSH, thyrotropin; Tg, thyroglobulin; TPOAb, thyroid peroxidase antibody; TgAb; thyroglobulin antibody. International System of Units: TT4, μg/dL = 12.87 nmol/L; TT3, ng/dL = 0.0154 nmol/L; fT4, ng/dL = 12.87 pmol/L; TBG, μg/mL = 0.0185 μmol/L.