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  1. Thong MK, Yunus ZM
    Ann Acad Med Singap, 2008 Dec;37(12 Suppl):66-5.
    PMID: 19904455
    Issues pertaining to the diagnosis and management of inborn errors of metabolism (IEM) in Malaysia included low awareness of atypical and variable presentations in IEMs leading to delayed diagnosis or treatment, absence of reliable population data on IEMs and involvement of multiple siblings in the same family due to consanguinity. The importance of careful family history taking and genetic counselling are emphasised. Selected testing of ill infants and children for IEM yielded a positive 2% (264/13,500) results for IEMs in Malaysia. Out of the 264 patients, the spectrum of IEMs in Malaysia included organic acidurias (98), aminoacidopathies (78), urea cycle defects (54), neurotransmitter conditions (12) and lysosomal disorders, mainly mucopolysaccharidosis (14). Confirmatory studies of IEMs are an important aspect of management of IEMs. There is a need for more metabolic specialists and funding for diagnosis and treatment of IEMs in Malaysia. Long-term care issues and cost-effectiveness of IEM therapy, supportive and preventive aspects will need further studies in Malaysia.
  2. Yunus ZM, Kamaludin DA, Mamat M, Choy YS, Ngu L
    JIMD Rep, 2012;5:99-107.
    PMID: 23430924 DOI: 10.1007/8904_2011_105
    INTRODUCTION: Maple Syrup Urine Disease (MSUD) is an autosomal recessive disorder caused by defects in the branched-chain α-ketoacid dehydrogenase complex resulting in accumulation of branched-chain amino acids (BCAAs) and corresponding branched-chain ketoacids (BCKAs) in tissues and plasma, which are neurotoxic. Early diagnosis and subsequent nutritional modification management can reduce the morbidity and mortality. Prior to 1990s, the diagnosis of MSUD and other inborn errors of metabolism (IEM) in Malaysia were merely based on clinical suspicion and qualitative one-dimensional thin layer chromatography technique. We have successfully established specific laboratory diagnostic techniques to diagnose MSUD and other IEM. We described here our experience in performing high-risk screening for IEM in Malaysia from 1999 to 2006. We analysed the clinical and biochemical profiles of 25 patients with MSUD.

    METHODS: A total of 12,728 plasma and urine samples from patients suspected of having IEM were received from physicians all over Malaysia. Plasma amino acids quantitation using fully automated amino acid analyzer and identification of urinary organic acids using Gas Chromatography Mass Spectrometry (GCMS). Patients' clinical information were obtained from the request forms and case records Results: Twenty-five patients were diagnosed MSUD. Nineteen patients (76%) were affected by classical MSUD, whereas six patients had non-classical MSUD. Delayed diagnosis was common among our case series, and 80% of patients had survived with treatment with mild-to-moderate learning difficulties.

    CONCLUSION: Our findings suggested that MSUD is not uncommon in Malaysia especially among the Malay and early laboratory diagnosis is crucial.

  3. Omar A, Jalil JA, Shakrin NM, Ngu LH, Yunus ZM
    Mol Genet Metab Rep, 2019 Jun;19:100469.
    PMID: 31193155 DOI: 10.1016/j.ymgmr.2019.100469
    Introduction: Mucopolysaccharidoses (MPS) are a group of inherited disorders caused by the deficiency of a specific lysosomal enzyme involved in glycosaminoglycans (GAGs) degradation. This enzyme deficiency leads to accumulation of GAGs in the lysosomes, resulting in organ dysfunction and enlargement. We aimed to detect cases of MPS in patients with suggestive signs and symptoms.

    Methods: This was a 2-year cross-sectional study conducted during June 2014 to May 2016. Urine and whole blood samples were taken from high-risk MPS patients. All urine samples were analysed for GAGs and characterised by high resolution electrophoresis (HRE). Whole blood was collected in ethylenediaminetetraacetic acid (EDTA) tube and analysed for specific enzymes based on the clinical history and HRE findings.

    Results: From the 60 samples tested, 15 were positive for MPS; (Type I = 1), (Type II = 4), (Type IIIA = 3), (Type IVA = 1), (Type VI = 6). The overall prevalence of MPS among high-risk Malaysian patients was 26% (95% CI 14.72% to 37.86%). One patient had mucolipidosis. The mean age of patients when diagnosed was 5 years old. Patients with MPS were more likely to present with hepatosplenomegaly compared to other symptoms (OR = 0.974, p 

  4. Omar A, Jalil JA, Shakrin NM, Ngu LH, Yunus ZM
    Data Brief, 2019 Aug;25:104377.
    PMID: 31516928 DOI: 10.1016/j.dib.2019.104377
    This article contains information related to a recent study "Selective screening for detection of mucopolysaccharidoses (MPS) in Malaysia; A Two-year Study" Affandi et al., 2019. Any patient registered under government healthcare facilities in Malaysia and fit at least two inclusion criteria were included in this selective screening. Urine and blood from these high risk patients were obtained and analysed for glycosaminoglycans (GAGs) level before characterization using high resolution electrophoresis (HRE). Thereafter, enzyme assay for different types of MPS based on result of HRE were determined using specific substrate. Demographic data as well as laboratory findings were tabulated and analysed. The data of this study demonstrate between clinical presentation and laboratory findings among high risk patients of MPS and can be employed to improve diagnosis of MPS.
  5. Zahid M, Khan AH, Yunus ZM, Chen BC, Steinmann B, Johannes H, et al.
    J Pak Med Assoc, 2019 Mar;69(3):432-436.
    PMID: 30890842
    In spite of the efforts and interventions by the Government of Pakistan and The World Health Organization, the neonatal mortality in Pakistan has declined by only 0.9% as compared to the global average decline of 2.1% between 2000 and 2010. This has resulted in failure to achieve the global Millennium Development Goal 4. Hypoxic-ischaemic encephalopathy, still birth, sepsis, pneumonia, diarrhoea and birth defects are commonly attributed as leading causes of neonatal mortality in Pakistan. Inherited metabolic disorders often present at the time of birth or the first few days of life. The clinical presentation of the inherited metabolic disorders including hypotonia, seizure and lactic acidosis overlap with clinical features of hypoxic-ischaemic encephalopathy and sepsis. Thus, these disorders are often either missed or wrongly diagnosed as hypoxicischaemic encephalopathy or sepsis unless the physicians actively investigate for the underlying inherited metabolic disorders. We present 4 neonates who had received the diagnosis of hypoxic-ischaemic encephalopathy and eventually were diagnosed to have various inherited metabolic disorders. Neonates with sepsis and hypoxic-ischaemic encephalopathy-like clinical presentation should be evaluated for inherited metabolic disorders.
  6. Chen BC, McGown IN, Thong MK, Pitt J, Yunus ZM, Khoo TB, et al.
    J Inherit Metab Dis, 2010 Dec;33 Suppl 3:S159-62.
    PMID: 20177786 DOI: 10.1007/s10545-010-9056-z
    Most cases of adenylosuccinate lyase (ADSL OMIM 103050) deficiency reported to date are confined to the various European ethnic groups. We report on the first Malaysian case of ADSL deficiency, which appears also to be the first reported Asian case. The case was diagnosed among a cohort of 450 patients with clinical features of psychomotor retardation, global developmental delay, seizures, microcephaly and/or autistic behaviour. The patient presented with frequent convulsions and severe myoclonic jerk within the first few days of life and severe psychomotor retardation. The high performance liquid chromatography (HPLC) profile of the urine revealed the characteristic biochemical markers of succinyladenosine (S-Ado) and succinyl-aminoimidazole carboximide riboside (SAICAr). The urinary S-Ado/SAICAr ratio was found to be 1.02 (type I ADSL deficiency). The patient was compound heterozygous for two novel mutations, c.445C > G (p.R149G) and c.774_778insG (p.A260GfsX24).
  7. Ali EZ, Khalid MK, Yunus ZM, Yakob Y, Chin CB, Abd Latif K, et al.
    Eur J Pediatr, 2016 Mar;175(3):339-46.
    PMID: 26440671 DOI: 10.1007/s00431-015-2644-z
    Carbamoyl phosphate synthetase 1 (CPS1) deficiency is a rare autosomal recessive disorder of ureagenesis presenting as life-threatening hyperammonemia. In this study, we present the main clinical features and biochemical and molecular data of six Malaysian patients with CPS1 deficiency. All the patients have neonatal-onset symptoms, initially diagnosed as infections before hyperammonemia was recognized. They have typical biochemical findings of hyperglutaminemia, hypocitrullinemia, and low to normal urinary excretion of orotate. One neonate succumbed to the first hyperammonemic decompensation. Five neonatal survivors received long-term treatment consisting of dietary protein restriction and ammonia-scavenging drugs. They have delayed neurocognitive development of varying severity. Genetic analysis revealed eight mutations in CPS1 gene, five of which were not previously reported. Five mutations were missense changes while another three were predicted to create premature stop codons. In silico analyses showed that these new mutations affected different CPS1 enzyme domains and were predicted to interrupt interactions at enzyme active sites, disturb local enzyme conformation, and destabilize assembly of intact enzyme complex.

    CONCLUSION: All mutations are private except one mutation; p.Ile1254Phe was found in three unrelated families. Identification of a recurrent p.Ile1254Phe mutation suggests the presence of a common and unique mutation in our population. Our study also expands the mutational spectrum of the CPS1 gene.

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