ObjectiveDyschromatosis universalis hereditaria (DUH) is a rare heterogeneous pigmentary genodermatosis, which was first described in 1933. The genetic cause has recently been discovered by the discovery of mutations in ABCB6. Here we investigated a Chinese family with typical features of autosomal dominant DUH and 3 unrelated patients with sporadic DUH.MethodsSkin tissues were obtained from the proband, of this family and the 3 sporadic patients. Histopathological examination and immunohistochemical analysis of ABCB6 were performed. Peripheral blood DNA samples were obtained from 21 affected, 14 unaffected, 11 spouses in the family and the 3 sporadic patients. A genome-wide linkage scan for the family was carried out to localize the causative gene. Exome sequencing was performed from 3 affected and 1 unaffected in the family. Sanger sequencing of ABCB6 was further used to identify the causative gene for all samples obtained from available family members, the 3 sporadic patients and a panel of 455 ethnically-matched normal Chinese individuals.ResultsHistopathological analysis showed melanocytes in normal control’s skin tissue and the hyperpigmented area contained more melanized, mature melanosomes than those within the hypopigmented areas. Empty immature melanosomes were found in the hypopigmented melanocytes. Parametric multipoint linkage analysis produced a HLOD score of 4.68, with markers on chromosome 2q35-q37.2. A missense mutation (c.1663 C>A, p.Gln555Lys) in ABCB6 was identified in this family by exome and Sanger sequencing. The mutation perfectly cosegregated with the skin phenotype. An additional mutation (g.776 delC, c.459 delC) in ABCB6 was found in an unrelated sporadic patient. No mutation in ABCB6 was discovered in the other two sporadic patients. Neither of the two mutations was present in the 455 controls. Melanocytes showed positive immunoreactivity to ABCB6.ConclusionOur data add new variants to the repertoire of ABCB6 mutations with DUH.
A stable-label i.v./oral study design was conducted to investigate the pharmacokinetics (PK) of odanacatib. Healthy, postmenopausal women received oral doses of unlabeled odanacatib administered simultaneously with a reference of 1 mg i.v. stable 13 C-labeled odanacatib. The absolute bioavailability of odanacatib was 30% at 50 mg (the phase 3 dose) and 70% at 10 mg, which is consistent with solubility-limited absorption. Odanacatib exposure (area under the curve from zero to infinity) increased by 15% and 63% when 50 mg was administered with low-fat and high-fat meals, respectively. This magnitude of the food effect is unlikely to be clinically important. The volume of distribution was ∼100 liters. The clearance was ∼0.8 l/h (13 ml/min), supporting that odanacatib is a low-extraction ratio drug. Population PK modeling indicated that 88% of individuals had completed absorption of >80% bioavailable drug within 24 hours, with modest additional absorption after 24 hours and periodic fluctuations in plasma concentrations contributing to late values for time to C max in some subjects.
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