Mutation analysis of seven patients with Waardenburg syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To perform genetic analysis for 7 patients with Waardenburg syndrome.</p><p><b>METHODS</b>Potential mutation of MITF, PAX3, SOX10 and SNAI2 genes was screened by polymerase chain reaction and direct sequencing. Functions of non-synonymous polymorphisms were predicted with PolyPhen2 software.</p><p><b>RESULTS</b>Seven mutations, including c.649-651delAGA (p.R217del), c.72delG (p.G24fs), c.185T>C (p.M62T), c.118C>T (p.Q40X), c.422T>C (p.L141P), c.640C>T (p.R214X) and c.28G>T(p.G43V), were detected in the patients. Among these, four mutations of the PAX3 gene (c.72delG, c.185T>C, c.118C>T and c.128G>T) and one SOX10 gene mutation (c.422T>C) were not reported previously. Three non-synonymous SNPs (c.185T>C, c.128G>T and c.422T>C) were predicted as harmful.</p><p><b>CONCLUSION</b>Genetic mutations have been detected in all patients with Waardenburg syndrome.</p>

Clinical classification and genetic mutation study of two pedigrees with type II Waardenburg syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the molecular etiology of two pedigrees affected with type II Waardenburg syndrome (WS2) and to provide genetic diagnosis and counseling.</p><p><b>METHODS</b>Blood samples were collected from the proband and his family members. Following extraction of genomic DNA, the coding sequences of PAX3, MITF, SOX10 and SNAI2 genes were amplified with PCR and subjected to DNA sequencing to detect potential mutations.</p><p><b>RESULTS</b>A heterozygous deletional mutation c.649_651delAGA in exon 7 of the MITF gene has been identified in all patients from the first family, while no mutation was found in the other WS2 related genes including PAX3, MITF, SOX10 and SNAI2.</p><p><b>CONCLUSION</b>The heterozygous deletion mutation c.649_651delAGA in exon 7 of the MITF gene probably underlies the disease in the first family. It is expected that other genes may also underlie WS2.</p>

Identification of a Novel De Novo Variant in the PAX3 Gene in Waardenburg Syndrome by Diagnostic Exome Sequencing: The First Molecular Diagnosis in Korea

Waardenburg syndrome (WS) is a clinically and genetically heterogeneous hereditary auditory pigmentary disorder characterized by congenital sensorineural hearing loss and iris discoloration. Many genes have been linked to WS, including PAX3, MITF, SNAI2, EDNRB, EDN3, and SOX10, and many additional genes have been associated with disorders with phenotypic overlap with WS. To screen all possible genes associated with WS and congenital deafness simultaneously, we performed diagnostic exome sequencing (DES) in a male patient with clinical features consistent with WS. Using DES, we identified a novel missense variant (c.220C>G; p.Arg74Gly) in exon 2 of the PAX3 gene in the patient. Further analysis by Sanger sequencing of the patient and his parents revealed a de novo occurrence of the variant. Our findings show that DES can be a useful tool for the identification of pathogenic gene variants in WS patients and for differentiation between WS and similar disorders. To the best of our knowledge, this is the first report of genetically confirmed WS in Korea.

Expression of nNOS, Pax3 and Cx43 proteins in early developing posterior horn of embryonic and fetal human spinal cord / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the distribution pattern of the expressions neuronal nitric oxide synthase (nNOS), Pax3 and connexin 43 (Cx43) proteins in the early developing posterior horn of embryonic and fetal human spinal cord.</p><p><b>METHODS</b>Immunohistochemistry was used to detect the expressions of nNOS, Pax3 and Cx43 proteins in the posterior horn of the spinal cord during the second, third and fourth month of human embryonic and fetal development.</p><p><b>RESULTS</b>In the second to fourth month of gestation, the expressions of nNOS and Pax3 proteins increased gradually from weak expression to strong expression in the posterior horn of the spinal cord. In the second to third month of development, Cx43 protein expression was negative in the posterior horn of the spinal cord, but positive in the myelin sheath. In the fourth month, positive Cx43 expression was detected in some of the cells in the posterior horn of the spinal cord.</p><p><b>CONCLUSION</b>nNOS, Pax3 and Cx43 proteins are closely related to the growth and development of the spinal cord in human embryos and fetuses.</p>

Expression of Cx43 and Pax3 in the small intestinal muscular layers of early human embryos / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the patterns of Cx43 and Pax3 protein expressions in the small intestinal muscular layers of human embryo during early development.</p><p><b>METHODS</b>Immunohistochemistry with SABC method was employed to examine the expression of Cx43 and Pax3 proteins in the muscular layers of the small intestine in early human embryos in the second to fourth months of gestation.</p><p><b>RESULTS</b>In the second month of gestation, the muscle layer of the small intestine was negative for Cx43 and Pax3 protein expressions. In the third month, Cx43 and Pax3 expressions were negative in the inner circular muscle layer, but some positive cells were found in the longitudinal muscle layer and the myenteric plexus. In the fourth month, positive expression of Cx43 and Pax3 proteins were seen in the entire muscle layer.</p><p><b>CONCLUSION</b>Cx43 and Pax3 proteins are closely related to the growth and development of the cells and tissues in the small intestinal muscle layer in human embryos.</p>

Nonsense mutations in the PAX3 gene cause Waardenburg syndrome type I in two Chinese patients / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSIONS</b>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.</p>

Expression of fusion gene PAX3/PAX7-FKHR and chromosomal aberration in rhabdomyosarcoma / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect the PAX3/PAX7-FKHR fusion transcripts to identify genetic alteration in embryonal rhabdomyosarcoma (ERMS) and alveolar rhabdomyosarcoma (ARMS) tissues.</p><p><b>METHODS</b>One-step reverse transcription- polymerase chain reaction (RT-PCR) were used to detect the expression of the PAX3/PAX7-FKHR fusion transcrips in 16 cases of rhabdomyosarcoma (7 cases of ARMS, 9 cases of ERMS) and 16 specimens were compared to the surrounding normal tissue. Comparative genomic hybridization (CGH) was employed to detect the genomic imbalance (DNA loss or amplification) in 16 RMS cases.</p><p><b>RESULTS</b>PAX3-FKHR fusion transcripts were positive in 3/7 and PAX 7-FKHR fusion transcripts were positive in 2/7 of ARMS patients, respectively, and were all negative in ERMS and Control tumors. There were different chromosome variations for each RMS, chromosome amplification was frequently seen in 1p36 (69%), 5q32 (56%), 8q21 (63%), 13q14 (69%), 19q (63%), 20q (56%). Chromosome loss was frequently seen in 3p21-pter (56%), 9p23-pter (50%), 10q (69%), 16/16q24 (56%).</p><p><b>CONCLUSION</b>One-step RT-PCR assay for detection specific fusion gene provides a useful tool for confirmation of the diagnosis of RMS in diagnostically difficult cases and in retrospective studies. Chimeric gene transcript resulting from specific chromosomal translocations is a reliable index for the molecular diagnosis of RMS.</p>