Publications by authors named "Lock Hock Ngu"

Neurodevelopmental disorder with or without autism or seizures (NEDAUS) is a neurodevelopmental disorder characterized by global developmental delay, speech delay, seizures, autistic features, and/or behavior abnormalities. It is caused by CUL3 (Cullin-3 ubiquitin ligase) haploinsufficiency. We collected clinical and molecular data from 26 individuals carrying pathogenic variants and variants of uncertain significance (VUS) in the CUL3 gene, including 20 previously unreported cases.

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Objective: The management of rare diseases is rarely addressed among policymakers and public communities. It is hindered by the lack of information on its epidemiology and burden, especially from the perspective of patients and families with rare diseases. This study aims to understand the perceptions of rare disease patients and their families in the management of rare diseases in Malaysia.

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Mucopolysaccharidosis (MPS) type II (Hunter syndrome) is a rare X-linked, recessive, lysosomal storage disorder caused by the deficit of the enzyme iduronate 2-sulfatase (IDS), resulting in accumulation of glycosaminoglycans (GAGs) impairing cellular function in multiple organ systems. Idursulfase (Elaprase, Takeda Pharmaceuticals) and idursulfase beta (Hunterase, GC Biopharma Corp.) are the two currently available enzyme replacement therapies (ERT) for MPS II in Malaysia.

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Background: Pompe disease is a rare glycogen storage disorder caused by deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA), leading to glycogen deposition in multiple tissues. Infantile-onset Pompe disease (IOPD) patients present within the first year of life with profound hypotonia and hypertrophic cardiomyopathy. Treatment with enzyme replacement therapy (ERT) has significantly improved survival for this otherwise lethal disorder.

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Article Synopsis
  • AADC deficiency is a rare genetic disorder that impacts the production of neurotransmitters like dopamine, norepinephrine, epinephrine, and serotonin, diagnosed via CSF/plasma analysis, AADC activity measurement, and genetic testing for the DDC gene.
  • In a study involving 348 patients, researchers identified 26 new DDC variants and analyzed their prevalence, finding that a specific splice variant, c.714+4A>T, was the most common, particularly prevalent in Taiwan and China.
  • The majority of identified genotypes were classified as pathogenic or likely pathogenic, with only one benign variant reported, and most AADC protein variants impacted protein function significantly based on their structural characteristics.*
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Background: Glycogen storage disease type 1a (GSD1a) is a rare autosomal recessive metabolic disorder characterized by hypoglycaemia, growth retardation, lactic acidosis, hepatomegaly, hyperlipidemia, and nephromegaly. GSD1a is caused by a mutation in the gene encoding glucose-6-phosphatase (G6Pase); an enzyme that catalyses the hydrolysis of glucose-6-phosphate (G6P) to phosphate and glucose.

Objective: To elaborate on the clinical findings, biochemical data, molecular genetic analysis, and short-term prognosis of 13 GSD1a patients in Malaysia.

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Peripheral demyelinating neuropathy, central dysmyelinating leukodystrophy, Waardenburg syndrome and Hirschsprung disease (PCWH) is a rare manifestation of Waardenburg-Shah syndrome associated with mutations in the gene. The phenotypic expression is variable, thus presenting a diagnostic challenge. Clinical manifestations of PCWH may mimic other neurocutaneous syndromes.

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Purpose: To compare patient care multipliers estimated from subjective evaluation against work sampling (WS) techniques in genetic nursing activities.

Methods: An observational WS technique was conducted from November to December 2019 with nine genetic nurses in a tertiary referral center in Malaysia. The WS activity instrument was devised, validated, and pilot tested.

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Labrune's syndrome, or leukoencephalopathy with brain calcifications and cysts (LCC), is a rare genetic syndrome with variable neurological presentations. Psychiatric manifestations and involuntary movements are uncommonly reported. We report the case of a 19-year-old female, initially diagnosed with Fahr's syndrome, who presented to us with acute psychosis, abnormal behavior and involuntary movements.

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Objective: Carnitine-acylcarnitine Translocase (CACT) deficiency (OMIM 212138) and carnitine palmitoyl transferase 2 (CPT2) deficiency (OMIM 60065050) are rare inherited disorders of mitochondrial long chain fatty acid oxidation. The aim of our study is to review the clinical, biochemical and molecular characteristics in children diagnosed with CACT and CPT2 deficiencies in Malaysia.

Design And Methods: This is a retrospective study.

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Article Synopsis
  • Various algorithms have been developed to detect copy number variations (CNVs) using exome sequencing (ES), but optimizing these algorithms for improved performance remains unaddressed.
  • In a study involving 1199 samples, researchers employed both eXome Hidden Markov Model (XHMM) and modified Nord's method to enhance CNV detection by analyzing data from all unrelated samples simultaneously and separating male and female sequences to reduce biases.
  • The optimized protocol led to the identification of pathogenic CNVs in 34 of 763 patients (4.5%), with a notable increase in detection among epilepsy patients from 9.9% to 13.4% using the new method.
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Quantitative estimates for the global impact of COVID-19 on the diagnosis and management of patients with inborn errors of metabolism (IEM) are lacking. We collected relevant data from 16 specialized medical centers treating IEM patients in Europe, Asia and Africa. The median decline of reported IEM related services in March 1st-May 31st 2020 compared to the same period in 2019 were as high as 60-80% with a profound impact on patient management and care for this vulnerable patient group.

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  • Inherited cutis laxa is a genetic condition that causes sagging skin and involves premature aging of connective tissues, often leading to severe neurological issues in specific syndromes.
  • A patient exhibiting movement disorders, unusual physical features, and intellectual disability was studied, revealing a significant mutation in the PI4K2A gene that impacts the synthesis of phosphatidylinositol lipids.
  • The research highlights the crucial role of the PI4K2A enzyme in regulating intracellular signaling and potential connections between metabolic defects and neurological symptoms associated with cutis laxa.
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The ubiquitin-proteasome system is the principal system for protein degradation mediated by ubiquitination and is involved in various cellular processes. Cullin-RING ligases (CRL) are one class of E3 ubiquitin ligases that mediate polyubiquitination of specific target proteins, leading to decomposition of the substrate. Cullin 3 (CUL3) is a member of the Cullin family proteins, which act as scaffolds of CRL.

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Objective: Rare diseases are often underdiagnosed, and their management is frequently complicated by a lack of access to treatment and information about the diseases. To allow for better policy planning, we sought to examine the current status of managing rare diseases in Malaysia.

Methods: This study was conducted in two phases.

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Unlabelled: Argininosuccinate lyase (ASL) deficiency impairs the function of the urea cycle that detoxifies blood ammonia in the body. Mutation that occurs in the gene is the cause of occurrence of ASL deficiency (ASLD). This deficiency causes hyperammonemia, hepatopathy and neurodevelopmental delay in patients.

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Background: Mucopolysaccharidosis IVA (MPS IVA) is an autosomal recessive lysosomal storage disease due to N-acetylgalactosamine-6-sulfatase (GALNS) deficiency. It results in accumulation of the glycosaminoglycans, keratan sulfate and chondroitin-6-sulfate, leading to skeletal and other systemic impairments. Data on MPS IVA in Asian populations are scarce.

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Background: Glycogen storage disease type III is an autosomal recessive disorder that is caused by deficiencies of the glycogen debranching enzyme. Mutations within the AGL gene have been found to be heterogeneous, with some common mutations being reported in certain populations. The mutation spectrum of AGL gene in the multi-ethnic Malaysian population is still unknown.

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Maple syrup urine disease (MSUD) is a rare autosomal recessive metabolic disorder. This disorder is usually caused by mutations in any one of the genes; , and , which represent E1α, E1β and E2 subunits of the branched-chain α-keto acid dehydrogenase (BCKDH) complex, respectively. This study presents the molecular characterization of 31 MSUD patients.

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Ornithine transcarbamylase deficiency (OTCD), an X-linked disorder that results from mutations in the gene, causes hyperammonemia and leads to various clinical manifestations. Mutations occurring close to the catalytic site of OTCase can cause severe OTCD phenotypes compared with those caused by mutations occurring on the surface of this protein. In this study, we report two novel missense mutations, Q171H and N199H, found in Malaysian patients.

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Background: Fructose-1,6-bisphosphatase (FBPase) deficiency is a rare autosomal recessive inborn error of gluconeogenesis. We reported the clinical findings and molecular genetic data in seven Malaysian patients with FBPase deficiency.

Methods: All patients diagnosed with FBPase deficiency from 2010 to 2015 were included in this study.

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