Pedigree chart, homozygosity mapping, and capillary sequencing. A. The patient was born to consanguineous parents who were first cousins. No other members of the family have exhibited the same symptoms. B. Black bar indicates IBD. Relatively long segments of IBD exist on chromosomes 3, 17, and 21. C. Patient has a homozygous nonsense mutation of TTC19 (c.829C > T, p.Q277*).