Nonsense mutations in the PAX3 gene cause Waardenburg syndrome type I in two Chinese patients.
BACKGROUND
Waardenburg syndrome type I (WS1) is an autosomal dominant disorder characterized by sensorineural hearing loss, pigmental abnormalities of the eye, hair and skin, and dystopia canthorum. The gene mainly responsible for WS1 is PAX3 which is involved in melanocytic development and survival. Mutations of PAX3 have been reported in familiar or sporadic patients with WS1 in several populations of the world except Chinese. In order to explore the genetic background of Chinese WS1 patients, a mutation screening of PAX3 gene was carried out in four WS1 pedigrees.


METHODS
A questionnaire survey and comprehensive clinical examination were conducted in four Chinese pedigrees of WS1. Genomic DNA from each patient and their family members was extracted and exons of PAX3 were amplified by PCR. PCR fragments were ethanol-purified and sequenced in both directions on an ABI_Prism 3100 DNA sequencer with the BigDye Terminator Cycle Sequencing Ready Reaction Kit. The sequences were obtained and aligned to the wild type sequence of PAX3 with the GeneTool program.


RESULTS
Two nonsense PAX3 mutations have been found in the study population. One is heterozygous for a novel nonsense mutation S209X. The other is heterozygous for a previously reported mutation in European population R223X. Both mutations create stop codons leading to truncation of the PAX3 protein.


CONCLUSIONS
This is the first demonstration of PAX3 mutations in Chinese WS1 patients and one of the few examples of an identical mutation of PAX3 occurred in different populations.
Yang
Shu-Zhi
SZ
Department of Otolaryngology Head and Neck Surgery, First Affiliated Hospital to Chinese General Hospital of PLA, Beijing 100037, China.
Cao
Ju-Yang
JY
Zhang
Rui-Ning
RN
Liu
Li-Xian
LX
Liu
Xin
X
Zhang
Xin
X
Kang
Dong-Yang
DY
Li
Mei
M
Han
Dong-Yi
DY
Yuan
Hui-Jun
HJ
Yang
Wei-Yan
WY
D018389:Codon, Nonsense; D005260:Female; D006801:Humans; D008297:Male; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics*; D014849:Waardenburg Syndrome / Q000235:genetics*
D018389:Codon, Nonsense; D000072041:PAX3 Transcription Factor; C489409:PAX3 protein, human; D051761:Paired Box Transcription Factors