Novel mutations of ABCB6 associated with autosomal dominant dyschromatosis universalis hereditaria.
OBJECTIVE
Dyschromatosis 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.


METHODS
Skin 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.


RESULTS
Histopathological 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.


CONCLUSIONS
Our data add new variants to the repertoire of ABCB6 mutations with DUH.
Institute of Laboratory Medicine, Jinling Hospital, Nanjing University School of Medicine, Nanjing, PR China.
Ying-Xia
YX
Cui
Xin-Yi
XY
Xia
Yang
Y
Zhou
Lin
L
Gao
Xue-Jun
XJ
Shang
Tong
T
Ni
Wei-Ping
WP
Wang
Xiao-Buo
XB
Fan
Hong-Lin
HL
Yin
Shao-Jun
SJ
Jiang
Bing
B
Yao
Yu-An
YA
Hu
Gang
G
Wang
Xiao-Jun
XJ
Li
D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000328:Adult; D044466:Asian People; D005260:Female; D008040:Genetic Linkage / Q000235:genetics; D020022:Genetic Predisposition to Disease; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D009154:Mutation; D010375:Pedigree; D010859:Pigmentation Disorders / Q000151:congenital* / Q000235:genetics; D012873:Skin Diseases, Genetic / Q000235:genetics*
C107991:ABCB6 protein, human; D018528:ATP-Binding Cassette Transporters