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Siu WK, Lam CW, Mak CM, Lau ETK, Tang MHY, Tang WF, Poon-Mak RSM, Lee CC, Hung SF, Leung PWL, Kwong KL, Yau EKC, Ng GSF, Fong NC, Chan KY. Diagnostic yield of array CGH in patients with autism spectrum disorder in Hong Kong. Clin Transl Med 2016; 5:18. [PMID: 27271878 PMCID: PMC4896892 DOI: 10.1186/s40169-016-0098-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 05/04/2016] [Indexed: 11/25/2022] Open
Abstract
Background Chromosomal microarray offers superior sensitivity for identification of submicroscopic copy number variants (CNV) and it is advocated to be the first tier genetic testing for patients with autism spectrum disorder (ASD). In this regard, diagnostic yield of array comparative genomic hybridization (CGH) for ASD patients is determined in a cohort of Chinese patients in Hong Kong. Methods A combined adult and paediatric cohort of 68 Chinese ASD patients (41 patients in adult group and 27 patients in paediatric group). The genomic DNA extracted from blood samples were analysed by array CGH using NimbleGen CGX-135K oligonucleotide array. Results We identified 15 CNV and eight of them were clinically significant. The overall diagnostic yield was 11.8 %. Five clinically significant CNV were detected in the adult group and three were in the paediatric group, providing diagnostic yields of 12.2 and 11.1 % respectively. The most frequently detected CNV was 16p13.11 duplications which were present in 4 patients (5.9 % of the cohort). Conclusions In this study, a satisfactory diagnostic yield of array CGH was demonstrated in a Chinese ASD patient cohort which supported the clinical usefulness of array CGH as the first line testing of ASD in Hong Kong. Electronic supplementary material The online version of this article (doi:10.1186/s40169-016-0098-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Wai-Kwan Siu
- Department of Pathology, The University of Hong Kong, 102 Pokfulam Road, Hong Kong, China.,Kowloon West Cluster Laboratory Genetics Service, Department of Pathology, Princess Margaret Hospital, Hong Kong, China
| | - Ching-Wan Lam
- Department of Pathology, The University of Hong Kong, 102 Pokfulam Road, Hong Kong, China.
| | - Chloe Miu Mak
- Kowloon West Cluster Laboratory Genetics Service, Department of Pathology, Princess Margaret Hospital, Hong Kong, China
| | - Elizabeth Tak-Kwong Lau
- Department of Obstetrics and Gynaecology, The University of Hong Kong, Queen Mary Hospital, Hong Kong, China
| | - Mary Hoi-Yin Tang
- Department of Obstetrics and Gynaecology, The University of Hong Kong, Queen Mary Hospital, Hong Kong, China
| | - Wing-Fai Tang
- Department of Obstetrics and Gynaecology, The University of Hong Kong, Queen Mary Hospital, Hong Kong, China
| | | | - Chi-Chiu Lee
- Department of Psychiatry, Kwai Chung Hospital, Hong Kong, China
| | - Se-Fong Hung
- Department of Psychiatry, Kwai Chung Hospital, Hong Kong, China
| | | | - Karen Ling Kwong
- Department of Paediatrics and Adolescent Medicine, Tuen Mun Hospital, Hong Kong, China
| | - Eric Kin-Cheong Yau
- Department of Paediatrics and Adolescent Medicine, Princess Margaret Hospital, Hong Kong, China
| | - Grace Sui-Fun Ng
- Department of Paediatrics and Adolescent Medicine, Princess Margaret Hospital, Hong Kong, China
| | - Nai-Chung Fong
- Department of Paediatrics and Adolescent Medicine, Princess Margaret Hospital, Hong Kong, China
| | - Kwok-Yin Chan
- Department of Paediatrics and Adolescent Medicine, Princess Margaret Hospital, Hong Kong, China
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Law CY, Chang STL, Cho SY, Yau EKC, Ng GSF, Fong NC, Lam CW. Clinical whole-exome sequencing reveals a novel missense pathogenic variant of GNAO1 in a patient with infantile-onset epilepsy. Clin Chim Acta 2015; 451:292-6. [PMID: 26485252 DOI: 10.1016/j.cca.2015.10.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 10/13/2015] [Accepted: 10/13/2015] [Indexed: 02/08/2023]
Abstract
BACKGROUND The cause of infantile-onset epilepsy is complex and is not easily recognized clinically, particularly in paediatric patients who present with non-specific neurological signs, no radiological abnormalities and no metabolic changes. CASE We report a case of infantile-onset epilepsy in a 10-month-old Chinese girl who presented with non-specific neurological signs, no radiological abnormalities and no biochemical disturbances. She first presented at birth with twitching movements and convulsions of an unknown aetiology. Ambulatory EEG showed epileptic rhythmic activities, the presence of asynchrony and runs of sharp waves over the right parietal and central areas. Given the non-specific neurological features and negative structural and biochemical findings, we applied clinical whole-exome sequencing (WES) to determine the underlying aetiology. WES revealed a novel heterozygous missense pathogenic variant, GNAO1:NM_020988.2:c.118G>A; NP_066268.1:p.Gly40Arg. A genetic analysis of the family confirmed the variant identified is a de novo mutation. CONCLUSIONS Clinical WES can streamline genetic analysis and sort out pathogenic genes in an unbiased approach. GNAO1 is a disease-causing gene for the autosomal dominant form of early infantile epileptic encephalopathy. The novel pathogenic variant identified in this case should contribute to our understanding of the expanding spectrum of infantile-onset epilepsy.
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Affiliation(s)
- Chun-Yiu Law
- Department of Pathology, The University of Hong Kong, Hong Kong, China
| | | | - Sun Young Cho
- Department of Laboratory Medicine, School of Medicine, Kyung Hee University, Seoul, Korea
| | - Eric Kin-Cheong Yau
- Department of Paediatrics and Adolescent Medicine, Princess Margaret Hospital, Hong Kong, China
| | - Grace Sui-Fun Ng
- Department of Paediatrics and Adolescent Medicine, Princess Margaret Hospital, Hong Kong, China
| | - Nai-Chung Fong
- Department of Paediatrics and Adolescent Medicine, Princess Margaret Hospital, Hong Kong, China
| | - Ching-Wan Lam
- Department of Pathology, The University of Hong Kong, Hong Kong, China.
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Lam CW, Li CK, Lai CK, Tong SF, Chan KY, Ng GSF, Yuen YP, Cheng AWF, Chan YW. DNA-based diagnosis of isolated sulfite oxidase deficiency by denaturing high-performance liquid chromatography. Mol Genet Metab 2002; 75:91-5. [PMID: 11825068 DOI: 10.1006/mgme.2001.3267] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Isolated sulfite oxidase deficiency is a rare autosomal recessive disease, characterized by severe neurological abnormalities, seizures, mental retardation, and dislocation of the ocular lenses, that often leads to death in infancy. There is a special demand for prenatal diagnosis, since no effective treatment is available for isolated sulfite oxidase deficiency. Until now, the cDNA sequence of the sulfite oxidase (SUOX) gene has been available, but the genomic sequence of the SUOX gene has not been published. In this study, we have performed a DNA-based diagnosis of isolated sulfite oxidase deficiency in a Chinese patient. To do so, we designed oligonucleotide primers for amplification of the predicted exons and intron-exon boundaries of the SUOX gene obtained from the completed draft version of the human genome. Using overlapping PCR products, we confirmed the flanking intronic sequences of the coding exons and that the entire 466-residue mature peptide is encoded by the last exon of the gene. We then performed mutation detection using denaturing high-performance liquid chromatography (DHPLC). The DHPLC chromatogram of exon 2b showed the presence of heteroduplex peaks only after mixing of the mutant DNA with the wild-type DNA, indicating the presence of a homozygous mutation. Direct DNA sequencing showed a homozygous base substitution at codon 160, changing the codon from CGG to CAG, which changes the amino acid from arginine to glutamine, i.e., R160Q. The DNA-based diagnosis of isolated sulfite oxidase deficiency will enable us to make an accurate determination of carrier status and to perform prenatal diagnosis of this disease. The availability of the genomic sequences of human genes from the completed draft human genome sequence will simplify the development of molecular genetic diagnoses of human diseases from peripheral blood DNA.
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Affiliation(s)
- Ching-Wan Lam
- Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China.
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