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Liu A.P.Y.,University of Hong Kong | Chow P.-C.,Queen Mary Hospital | Lee P.P.W.,University of Hong Kong | Mok G.T.K.,University of Hong Kong | And 9 more authors.
European Journal of Medical Genetics

22q11.2 deletion syndrome (22q11.2DS) is a multi-systemic disorder with high phenotypic variability. Under-diagnosis in adults is common and recognition of facial dysmorphic features can be affected by age and ethnicity. This study aims to determine the prevalence of undiagnosed 22q11.2DS in adult Chinese patients with conotruncal anomalies and to delineate their facial dysmorphisms and extra-cardiac manifestations. We recruited consecutively 156 patients with conotruncal anomalies in an adult congenital heart disease (CHD) clinic in Hong Kong and screened for 22q11.2DS using fluorescence-PCR and fluorescence in-situ hybridization. Assessment for dysmorphic features was performed by a cardiologist at initial screening and then by a clinical geneticist upon result disclosure. Clinical photographs were taken and childhood photographs collected. Eighteen patients (11.5%) were diagnosed with 22q11.2DS, translating into 1 previously unrecognized diagnosis of 22q11.2DS in every 10 adult patients with conotruncal anomalies. While dysmorphic features were detected by our clinical geneticist in all patients, only two-thirds were considered dysmorphic by our cardiologist upon first assessment. Evolution of facial dysmorphic features was noted with age. Extra-cardiac manifestations included velopharyngeal incompetence or cleft palate (44%), hypocalcemia (39%), neurodevelopmental anomalies (33%), thrombocytopenia (28%), psychiatric disorders (17%), epilepsy (17%) and hearing loss (17%). We conclude that under-diagnosis of 22q11.2DS in Chinese adults with conotruncal defects is common and facial dysmorphic features may not be reliably recognized in the setting of adult CHD clinic, referral for genetic evaluation and molecular testing for 22q11.2DS should be offered to patients with conotruncal defects. © 2014 Elsevier Masson SAS. Source

Beddow R.A.,Central and Southern Genetic Services | Smith M.,Central and Southern Genetic Services | Kidd A.,Cantebury Health Laboratory | Corbett R.,Christchurch Hospital | Hunter A.G.,Clinical Genetic Service
European Journal of Medical Genetics

We report an 18 year old patient with mild intellectual disability who was diagnosed with a late onset teratoid/rhabdoid tumour by histological and immunohistochemical studies. Array-CGH studies, performed on a peripheral blood sample, showed a 3.4. Mb deletion of chromosome 22q11.2, distal to the common DiGeorge syndrome (DGS) or Velocardiofacial syndrome (VCFs) region. This deletion is consistent with a diagnosis of distal 22q11.2 deletion syndrome. The deletion encompasses the INI1/SMARCB1 tumour suppressor gene. Biallelic inactivation of this gene is characteristic of atypical teratoid/rhabdoid tumours.Although several constitutional chromosome conditions are known to have increased susceptibility to various forms of cancer, very little is known regarding the magnitude of risk for malignancy associated with distal 22q11.2 deletion syndrome. In view of this finding we suggest that patients diagnosed with distal 22q11.2 deletion syndrome undergo careful prolonged monitoring for this type of tumour.This case demonstrates the need to carefully assess regions found to be deleted in individuals, referred for dysmorphia and/or developments delay, by array-CGH for the presence of genes known to be implicated in malignancy. © 2010 Elsevier Masson SAS. Source

Yeung K.S.,University of Hong Kong | Chee Y.Y.,University of Hong Kong | Luk H.M.,Clinical Genetic Service | Kan A.S.Y.,University of Hong Kong | And 6 more authors.
American Journal of Medical Genetics, Part A

Wereport on a baby girl with multiple congenital abnormalities, including cleft palate, intrauterine growth restriction, and double outlet right ventricle (DORV) with ventricular septal defect. She had an unbalanced chromosome translocation t (X;15) resulting in monosomy 15pter → p10 and trisomy Xq13.1 → q28. All three copies of Xq encompass the XIST gene. It is known that X chromosome inactivation could spread to the autosome part of an unbalanced translocation involving chromosome X and an autosome. To confirm the spread of X chromosome inactivation on chromosome 15, we evaluate the methylation change by the HumanMethylation450 BeadChip, a whole genome DNA methylation micorarray that includes 15,259 probes spanning 717 genes on chromosome 15. Results showed there was gain in DNA methylation of more than 20% in 586 CpG sites spanning the long arm of chromosome 15. We further examined the hypermethylated CpG sites located in CpG-island promoter, because genes subjected to X chromosome inactivation will have an increase in DNA methylation level in this region. A total of 75 sites representing 24 genes were hypermethylated. Nearly all of these probes are located in region proximal to the breakpoint, from 15q11.2 to 15q21.3 (35Mb) suggesting that X inactivation was spread to the proximal region of 15q. Gain of DNA methylation, especially in the CpG-island promoter, can result in functional inactivation of genes, and therefore could potentially worsen the phenotype of our patient. © 2014 Wiley Periodicals, Inc. Source

Luk H.M.,Clinical Genetic Service | Lo I.F.M.,Clinical Genetic Service
European Journal of Medical Genetics

AS(OMIM #105830) is a neurodevelopmental disease that characterized by severe intellectual disability, lack of speech, happy disposition, ataxia, epilepsy and distinct behavioural profile.A tertiary wide study was performed in Hong Kong with aim to examine the clinical and molecular features, genotype-phenotype correlation of the Angelman syndrome (AS) patients. There were total 55 molecularly confirmed AS between January 1995 to September 2015 for review. 65.5% of them were caused by maternal microdeletion, 10.9% by paternal uniparental disomy, 3.6% by imprinting center defect and 14.5% by UBE3A gene mutation. Genotype-phenotype correlation showed epilepsy and microcephaly is more common in microdeletion type as compared with non-microdeletional type. We have concluded that the incidence rate, clinical features and underlying genetic mechanisms in Hong Kong Chinese were comparable with other western populations. The overall average age of diagnosis in this cohort was 6.2 years old (95% C.I was 5.0-7.5 years old). It is hope that by increasing awareness and early referral could result in early diagnosis and better management for AS patient. © 2016 Elsevier Masson SAS. Source

Edwards J.J.,Mount Sinai School of Medicine | Martinelli S.,Oncology and Molecular Medicine | Pannone L.,Oncology and Molecular Medicine | Lo I.F.-M.,Clinical Genetic Service | And 5 more authors.
American Journal of Medical Genetics, Part A

The RASopathies are a relatively common group of phenotypically similar and genetically related autosomal dominant genetic syndromes caused by missense mutations affecting genes participating in the RAS/mitogen-activated protein kinase (MAPK) pathway that include Noonan syndrome (NS) and Noonan syndrome with multiple lentigines (NSML, formerly LEOPARD syndrome). NS and NSML can be difficult to differentiate during infancy, but the presence of multiple lentigines, café au lait spots, and specific cardiac defects facilitate the diagnosis. Furthermore, individual PTPN11 missense mutations are highly specific to each syndrome and engender opposite biochemical alterations on the function of SHP-2, the protein product of that gene. Here, we report on a 5-year-old male with two de novo PTPN11 mutations in cis, c.1471C>T (p.Pro491Ser), and c.1492C>T (p.Arg498Trp), which are associated with NS and NSML, respectively. This boy's phenotype is intermediate between NS and NSML with facial dysmorphism, short stature, mild global developmental delay, pulmonic stenosis, and deafness but absence of café au lait spots or lentigines. The double-mutant SHP-2 was found to be catalytically impaired. This raises the question of whether clinical differences between NS and NSML can be ascribed solely to the relative SHP-2 catalytic activity. © 2014 Wiley Periodicals, Inc. Source

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