Genome-wide linkage, exome sequencing and functional analyses identify ABCB6 as the pathogenic gene of dyschromatosis universalis hereditaria.
BACKGROUND
As a genetic disorder of abnormal pigmentation, the molecular basis of dyschromatosis universalis hereditaria (DUH) had remained unclear until recently when ABCB6 was reported as a causative gene of DUH.


METHODS
We performed genome-wide linkage scan using Illumina Human 660W-Quad BeadChip and exome sequencing analyses using Agilent SureSelect Human All Exon Kits in a multiplex Chinese DUH family to identify the pathogenic mutations and verified the candidate mutations using Sanger sequencing. Quantitative RT-PCR and Immunohistochemistry was performed to verify the expression of the pathogenic gene, Zebrafish was also used to confirm the functional role of ABCB6 in melanocytes and pigmentation.


RESULTS
Genome-wide linkage (assuming autosomal dominant inheritance mode) and exome sequencing analyses identified ABCB6 as the disease candidate gene by discovering a coding mutation (c.1358C>T; p.Ala453Val) that co-segregates with the disease phenotype. Further mutation analysis of ABCB6 in four other DUH families and two sporadic cases by Sanger sequencing confirmed the mutation (c.1358C>T; p.Ala453Val) and discovered a second, co-segregating coding mutation (c.964A>C; p.Ser322Lys) in one of the four families. Both mutations were heterozygous in DUH patients and not present in the 1000 Genome Project and dbSNP database as well as 1,516 unrelated Chinese healthy controls. Expression analysis in human skin and mutagenesis interrogation in zebrafish confirmed the functional role of ABCB6 in melanocytes and pigmentation. Given the involvement of ABCB6 mutations in coloboma, we performed ophthalmological examination of the DUH carriers of ABCB6 mutations and found ocular abnormalities in them.


CONCLUSIONS
Our study has advanced our understanding of DUH pathogenesis and revealed the shared pathological mechanism between pigmentary DUH and ocular coloboma.
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Hospital for Skin Diseases, Shandong University, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China ; Shandong Provincial Medical Center for Dermatovenereology, Jinan, Shandong, China.
Hong
H
Liu
Human Genetics, Genome Institute of Singapore, ASTAR, Singapore, Singapore.
Yi
Y
Li
Human Genetics, Genome Institute of Singapore, ASTAR, Singapore, Singapore.
Ken Kwok Hon
KK
Hung
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China.
Na
N
Wang
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China.
Chuan
C
Wang
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China.
Xuechao
X
Chen
Human Genetics, Genome Institute of Singapore, ASTAR, Singapore, Singapore.
Donglai
D
Sheng
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China.
Xi'an
X
Fu
Human Genetics, Genome Institute of Singapore, ASTAR, Singapore, Singapore.
Kelvin
K
See
Human Genetics, Genome Institute of Singapore, ASTAR, Singapore, Singapore.
Jia Nee
JN
Foo
Human Genetics, Genome Institute of Singapore, ASTAR, Singapore, Singapore.
Huiqi
H
Low
Human Genetics, Genome Institute of Singapore, ASTAR, Singapore, Singapore.
Herty
H
Liany
Human Genetics, Genome Institute of Singapore, ASTAR, Singapore, Singapore.
Ishak Darryl
ID
Irwan
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China.
Jian
J
Liu
Shandong Provincial Hospital for Skin Diseases, Shandong University, Jinan, Shandong, China ; Shandong Provincial Medical Center for Dermatovenereology, Jinan, Shandong, China.
Baoqi
B
Yang
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China.
Mingfei
M
Chen
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China.
Yongxiang
Y
Yu
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China.
Gongqi
G
Yu
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China.
Guiye
G
Niu
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China.
Jiabao
J
You
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China.
Yan
Y
Zhou
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China.
Shanshan
S
Ma
Shandong provincial Eye Hospital, Jinan, Shandong, China.
Ting
T
Wang
Shandong Provincial Hospital for Skin Diseases, Shandong University, Jinan, Shandong, China ; Shandong Provincial Medical Center for Dermatovenereology, Jinan, Shandong, China.
Xiaoxiao
X
Yan
National Skin Centre, Singapore, Singapore.
Boon Kee
BK
Goh
Institute of Medical Biology, ASTAR, Singapore, Singapore.
John E A
JE
Common
Institute of Medical Biology, ASTAR, Singapore, Singapore.
Birgitte E
BE
Lane
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China.
Yonghu
Y
Sun
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China.
Guizhi
G
Zhou
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China.
Xianmei
X
Lu
Weifang People's Hospital, Weifang, Shandong, China.
Zhenhua
Z
Wang
Shandong Provincial Hospital for Skin Diseases, Shandong University, Jinan, Shandong, China ; Shandong Provincial Medical Center for Dermatovenereology, Jinan, Shandong, China.
Hongqing
H
Tian
Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College Nanjing, Jiangsu, China.
Yuanhua
Y
Cao
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China.
Shumin
S
Chen
Shandong University, Jinan, Shandong, China.
Qiji
Q
Liu
Human Genetics, Genome Institute of Singapore, ASTAR, Singapore, Singapore ; School of Life Sciences, Anhui Medical University, Hefei, Anhui, China.
Jianjun
J
Liu
Shandong Provincial Institute of Dermatology and Venereology, Provincial Academy of Medical Science, Jinan, Shandong, China ; Shandong Provincial Hospital for Skin Diseases, Shandong University, Jinan, Shandong, China ; Shandong Provincial Key Lab for Dermatovenereology, Jinan, Shandong, China ; Shandong Provincial Medical Center for Dermatovenereology, Jinan, Shandong, China ; Shandong Clinical College, Anhui Medical University, Jinan, Shandong, China.
Furen
F
Zhang
D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D004252:DNA Mutational Analysis; D059472:Exome / Q000235:genetics*; D005192:Family Health; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D055106:Genome-Wide Association Study / Q000379:methods*; D006801:Humans; D007150:Immunohistochemistry; D008126:Lod Score; D008297:Male; D008544:Melanocytes / Q000378:metabolism; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010375:Pedigree; D010859:Pigmentation Disorders / Q000151:congenital* / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D012867:Skin / Q000378:metabolism / Q000473:pathology; D012873:Skin Diseases, Genetic / Q000235:genetics* / Q000378:metabolism; D015027:Zebrafish / Q000196:embryology / Q000235:genetics / Q000378:metabolism
C107991:ABCB6 protein, human; D018528:ATP-Binding Cassette Transporters