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Fulltext Alkaptonuria - more than meets the eye

Ong SG, Chen BC

Med J Malaysia, 2013;68(1):67-8.
PMID: 23466771 MyJurnal

An elderly gentleman with chronic lower back and bilateral knee pain was found to have clinical and radiographic findings consistent with alkaptonuria. Diagnosis was confirmed by the detection of elevated homogentisic acid level in the urine using gas chromatography-mass spectrometry.
Fulltext Argininosuccinic aciduria: clinical and biochemical phenotype findings in Malaysian children

Chen BC, Ngu LH, Zabedah MY

Malays J Pathol, 2010 Dec;32(2):87-95.
PMID: 21329179 MyJurnal

Argininosuccinic aciduria is an inborn error of the urea cycle caused by deficiency of argininosuccinate lyase (ASL). ASL-deficient patients present with progressive intoxication due to accumulation of ammonia in the body. Early diagnosis and treatment of hyperammonemia are necessary to improve survival and prevent long-term handicap. Two clinical phenotypes have been recognized--neonatal acute and milder late-onset form. We investigated patients with hyperammonemia by a stepwise approach in which quantitative amino acids analysis was the core diagnostic procedure. Here, we describe the clinical phenotypes and biochemical characteristics in diagnosing this group of patients. We have identified 13 patients with argininosuccinic aciduria from 2003 till 2009. Ten patients who presented with acute neonatal hyperammonemic encephalopathy had markedly elevated blood ammonia (> 430 micromol/L) within the first few days of life. Three patients with late-onset disease had more subtle clinical presentations and they developed hyperammonemia only during the acute catabolic state at two to twelve months of age. Their blood ammonia was mild to moderately elevated (> 75-265 micromol/L). The diagnosis was confirmed by detection of excessive levels of argininosuccinate in the urine and/or plasma. They also have moderately increased levels of citrulline and, low levels of arginine and ornithine in their plasma. Two patients succumbed to the disease. To date, eleven patients remained well on a dietary protein restriction, oral ammonia scavenging drugs and arginine supplementation. The majority of them have a reasonable good neurological outcome.
Fulltext Mitochondrial Neurogastrointestinal Encephalomyopathy Disease in Three Siblings from Pakistan with a Novel Mutation

Durrani S, Chen BC, Yakob Y, Hian LS, Afroze B

J Pediatr Genet, 2019 Mar;8(1):15-19.
PMID: 30775048 DOI: 10.1055/s-0038-1661411

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare multisystem autosomal recessive disorder. The disease is clinically heterogeneous with gastrointestinal symptoms of intestinal dysmotility and cachexia as well as neurological symptoms of ophthalmoplegia, neuropathy, sensorineural hearing impairment, and diffuse leukoencephalopathy being most prominent. MNGIE is caused by mutations in TYMP , a gene that encodes thymidine phosphorylase (TP)-a cytosolic enzyme. Mutations in TYMP lead to very low TP catalytic activity, resulting in dramatically increased thymidine and deoxyuridine in plasma. We describe the clinical, biochemical, and neuroimaging findings of three boys with MNGIE from a Pakistani family with a novel homozygous mutation, c.798_801dupCGCG p. (Ala268Argfs*?), in exon 7 of TYMP .
Effectiveness of amylmetacresol and 2,4-dichlorobenzyl alcohol throat lozenges in patients with acute sore throat due to upper respiratory tract infection: a systematic review protocol

Tan TW, Chen BC, Tan HL, Chang CM

JBI Database System Rev Implement Rep, 2017 Apr;15(4):862-872.
PMID: 28398972 DOI: 10.11124/JBISRIR-2016-003034

REVIEW QUESTION/OBJECTIVE: This review aims to determine the best available evidence related to the effectiveness of amylmetacresol and 2,4-dichlorobenzyl alcohol throat lozenges in patients with acute sore throat due to upper respiratory tract infection (URTI). The objective is to examine the analgesic properties of amylmetacresol and 2,4-dichlorobenzyl alcohol (AMC/DCBA) throat lozenge comparing with placebo for the relief of pain in patients with acute sore throat due to URTIs.The review question is:More specifically, the objectives are to.
Fulltext Molybdenum cofactor deficiency in a Malaysian child

Ngu LH, Afroze B, Chen BC, Affandi O, Zabedah MY

Singapore Med J, 2009 Oct;50(10):e365-7.
PMID: 19907877

Molybdenum cofactor deficiency is a rare autosomal recessive disorder with devastating neurological manifestations, characterised by neonatal-onset encephalopathy mimicking hypoxic-ischaemic insult, intractable seizure, and feeding and respiratory difficulties. It is often fatal in the early life. We report an affected 8-year-old boy, who presented with severe neurological manifestations since birth, but without clinically-significant seizure. Molybdenum cofactor deficiency must be included in the differential diagnosis of patients presenting with unexplained encephalopathy in the newborn period, and whose neuroimaging findings are consistent with hypoxic ischaemic encephalopathy. The classic laboratory hallmark of this disorder is low serum uric acid, positive urine sulphite dipstick test, and elevated urinary S-sulphocysteine, hypoxanthine and xanthine.
Fulltext Dihydropyrimidine dehydrogenase deficiency in two malaysian siblings with abnormal MRI findings

Chen BC, Mohd Rawi R, Meinsma R, Meijer J, Hennekam RC, van Kuilenburg AB

Mol Syndromol, 2014 Dec;5(6):299-303.
PMID: 25565930 DOI: 10.1159/000366074

Dihydropyrimidine dehydrogenase (DPD) deficiency is an autosomal recessive disorder of the pyrimidine metabolism. Deficiency of this enzyme leads to an accumulation of thymine and uracil and a deficiency of metabolites distal to the catabolic enzyme. The disorder presents with a wide clinical spectrum, ranging from asymptomatic to severe neurological manifestations, including intellectual disability, seizures, microcephaly, autistic behavior, and eye abnormalities. Here, we report on an 11-year-old Malaysian girl and her 6-year-old brother with DPD deficiency who presented with intellectual disability, microcephaly, and hypotonia. Brain MRI scans showed generalized cerebral and cerebellar atrophy and callosal body dysgenesis in the boy. Urine analysis showed strongly elevated levels of uracil in the girl and boy (571 and 578 mmol/mol creatinine, respectively) and thymine (425 and 427 mmol/mol creatinine, respectively). Sequence analysis of the DPYD gene showed that both siblings were homozygous for the mutation c.1651G>A (pAla551Thr).
Inherited metabolic disorders presenting as hypoxic ischaemic encephalopathy: A case series of patients presenting at a tertiary care hospital in Pakistan

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.
Fulltext Fructose-1,6-bisphosphatase deficiency as a cause of recurrent hypoglycemia and metabolic acidosis: Clinical and molecular findings in Malaysian patients

Moey LH, Abdul Azize NA, Yakob Y, Leong HY, Keng WT, Chen BC, et al.

Pediatr Neonatol, 2018 08;59(4):397-403.
PMID: 29203193 DOI: 10.1016/j.pedneo.2017.11.006

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. Their clinical and laboratory data were collected retrospectively.
RESULTS: All the patients presented with recurrent episodes of hypoglycemia, metabolic acidosis, hyperlactacidemia and hepatomegaly. All of them had the first metabolic decompensation prior to 2 years old. The common triggering factors were vomiting and infection. Biallelic mutations in FBP1 gene (MIM*611570) were identified in all seven patients confirming the diagnosis of FBPase deficiency. In four patients, genetic study was prompted by detection of glycerol or glycerol-3-phosphate in urine organic acids analysis. One patient also had pseudo-hypertriglyceridemia. Seven different mutations were identified in FBP1, among them four mutations were new: three point deletions (c.392delT, c.603delG and c.704delC) and one splice site mutation (c.568-2A > C). All four new mutations were predicted to be damaging by in silico analysis. One patient presented in the neonatal period and succumbed due to sepsis and multi-organ failure. Among six survivors (current age ranged from 4 to 27 years), four have normal growth and cognitive development. One patient had short stature and another had neurological deficit following status epilepticus due to profound hypoglycemia.
CONCLUSION: FBPase deficiency needs to be considered in any children with recurrent hypoglycemia and metabolic acidosis. Our study expands the spectrum of FBP1 gene mutations.
Treatment of Lesch-Nyhan disease with S-adenosylmethionine: experience with five young Malaysians, including a girl

Chen BC, Balasubramaniam S, McGown IN, O'Neill JP, Chng GS, Keng WT, et al.

Brain Dev, 2014 Aug;36(7):593-600.
PMID: 24055166 DOI: 10.1016/j.braindev.2013.08.013

BACKGROUND: Lesch-Nyhan disease (LND) is a rare X-linked recessive neurogenetic disorder caused by deficiency of the purine salvage enzyme hypoxanthine phosphoribosyltransferase (HPRT, EC 2.4.2.8) which is responsible for recycling purine bases into purine nucleotides. Affected individuals have hyperuricemia leading to gout and urolithiasis, accompanied by a characteristic severe neurobehavioural phenotype with compulsive self-mutilation, extrapyramidal motor disturbances and cognitive impairment.
AIM: For its theoretical therapeutic potential to replenish the brain purine nucleotide pool, oral supplementation with S-adenosylmethionine (SAMe) was trialed in 5 Malaysian children with LND, comprising 4 related Malay children from 2 families, including an LND girl, and a Chinese Malaysian boy.
RESULTS: Dramatic reductions of self-injury and aggressive behaviour, as well as a milder reduction of dystonia, were observed in all 5 patients. Other LND neurological symptoms did not improve during SAMe therapy.
DISCUSSION: Molecular mechanisms proposed for LND neuropathology include GTP depletion in the brain leading to impaired dopamine synthesis, dysfunction of G-protein-mediated signal transduction, and defective developmental programming of dopamine neurons. The improvement of our LND patients on SAMe, particularly the hallmark self-injurious behaviour, echoed clinical progress reported with another purine nucleotide depletion disorder, Arts Syndrome, but contrasted lack of benefit with the purine disorder adenylosuccinate lyase deficiency. This first report of a trial of SAMe therapy in LND children showed remarkably encouraging results that warrant larger studies.
KEYWORDS: Aggression; Dystonia; HGPRT; HPRT1; Lesch–Nyhan disease; S-adenosylmethionine; Self-injury
Adenylosuccinate lyase deficiency in a Malaysian patient, with novel adenylosuccinate lyase gene mutations

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).
Hyperexcretion of homocitrulline in a Malaysian patient with lysinuric protein intolerance

Habib A, Md Yunus Z, Azize NA, Ch'ng GS, Ong WP, Chen BC, et al.

Eur J Pediatr, 2013 Sep;172(9):1277-81.
PMID: 23358709 DOI: 10.1007/s00431-013-1947-1

Lysinuric protein intolerance (LPI; MIM 222700) is an inherited aminoaciduria with an autosomal recessive mode of inheritance. Biochemically, affected patients present with increased excretion of the cationic amino acids: lysine, arginine, and ornithine. We report the first case of LPI diagnosed in Malaysia presented with excessive excretion of homocitrulline. The patient was a 4-year-old male who presented with delayed milestones, recurrent diarrhea, and severe failure to thrive. He developed hyperammonemic coma following a forced protein-rich diet. Plasma amino acid analysis showed increased glutamine, alanine, and citrulline but decreased lysine, arginine and ornithine. Urine amino acids showed a marked excretion of lysine and ornithine together with a large peak of unknown metabolite which was subsequently identified as homocitrulline by tandem mass spectrometry. Molecular analysis confirmed a previously unreported homozygous mutation at exon 1 (235 G > A, p.Gly79Arg) in the SLC7A7 gene. This report demonstrates a novel mutation in the SLC7A7 gene in this rare inborn error of diamino acid metabolism. It also highlights the importance of early and efficient treatment of infections and dehydration in these patients.
CONCLUSION: The diagnosis of LPI is usually not suspected by clinical findings alone, and specific laboratory investigations and molecular analysis are important to get a definitive diagnosis.