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Fulltext Identification of mutations in Malaysian patients with argininosuccinate lyase (ASL) deficiency

Ali EZ, Yakob Y, Ngu LH

Mol Genet Metab Rep, 2019 Dec;21:100525.
PMID: 31709144 DOI: 10.1016/j.ymgmr.2019.100525

Argininosuccinate lyase (ASL) deficiency impairs the function of the urea cycle that detoxifies blood ammonia in the body. Mutation that occurs in the ASL gene is the cause of occurrence of ASL deficiency (ASLD). This deficiency causes hyperammonemia, hepatopathy and neurodevelopmental delay in patients. In this study, the clinical characteristics and molecular analysis of 10 ASLD patients were presented. 8 patients were associated with severe neonatal onset, while the other 2 were associated with late onset. Molecular analysis of ASL gene identified four new missense variants, which were c.778C>T, p.(Leu260Arg), c.1340G>C, p.(Ser447Thr), c.436C>G, p.(Arg146Gly) and c.595C>G, p.(Leu199Val) and four reported missense variants, which were c.638G>A, p.(Arg213Gln); c.556C>T, p.(Arg186Trp), c.578G>A, p.(Arg193Gln) and c.436C>G, p.(Arg146Trp). In silico servers predicted all new and reported variants as disease-causing. Structural examination exhibited that all pathogenic variants affected the stability of the tetrameric ASL structure by disturbing the bonding pattern with the neighboring residues.
Conclusion: This study revealed the genetic heterogeneity among Malaysian ASL patients. This study has also expanded the mutational spectrum of the ASL.
Adrenal insufficiency in a child with MELAS syndrome

Afroze B, Amjad N, Ibrahim SH, Humayun KN, Yakob Y

Brain Dev, 2014 Nov;36(10):924-7.
PMID: 24508408 DOI: 10.1016/j.braindev.2013.12.009

Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) are established subgroups of mitochondrial encephalomyopathy. m.3243A>G a common point mutation is detected in tRNA in majority of patients with MELAS phenotype whereas m.8344A>G point mutation in tRNA is observed, in MERRF phenotype. Adrenal insufficiency has not been reported in mitochondrial disease, except in Kearns-Sayre Syndrome (KSS), which is a mitochondrial deletion syndrome. We report an unusual presentation in a five year old boy who presented with clinical phenotype of MELAS and was found to have m.8344A>G mutation in tRNA. Addison disease was identified due to hyperpigmentation of lips and gums present from early childhood. This is the first report describing adrenal insufficiency in a child with MELAS phenotype.
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 .
Fulltext Biochemical and molecular characteristics of Malaysian patients with lysinuric protein intolerance

Habib A, Azize NA, Yakob Y, Md Yunus Z, Wee TK

Malays J Pathol, 2016 Dec;38(3):305-310.
PMID: 28028301 MyJurnal

Lysinuric protein intolerance (LPI) is an inborn error of dibasic amino acid transport due to a defect in the dibasic amino acid transporter in the renal and intestine and has a heterogenous presentation. Three Malaysian patients with LPI were studied and their biochemical and molecular findings compared. There were differences and similarities in the biochemical and molecular findings. Molecular analysis of SLC7A7 gene revealed a novel mutation c.235G>A; p.(Gly79Arg) in exon three in Patient 1 and a mutation c.1417C>T; p.(Arg473*) in exon 10 in patient 2 and 3. The degree of concentration of dibasic amino acids may determine the type of disease of the cell membrane transport, however, a positive molecular confirmation will secure the diagnosis.
Fulltext Late-Onset Glycogen Storage Disease Type II (Pompe's Disease) with a Novel Mutation: A Malaysian Experience

Fu Liong H, Abdul Wahab SA, Yakob Y, Lock Hock N, Thong WK, Viswanathan S

Case Rep Neurol Med, 2014;2014:926510.
PMID: 25093132 DOI: 10.1155/2014/926510

Pompe's disease (acid maltase deficiency, glycogen storage disease type II) is an autosomal recessive disorder caused by a deficiency of lysosomal acid α-1,4-glucosidase, resulting in excessive accumulation of glycogen in the lysosomes and cytoplasm of all tissues, most notably in skeletal muscles. We present a case of adult-onset Pompe's disease with progressive proximal muscles weakness over 5 years and respiratory failure on admission, requiring prolonged mechanical ventilation. Electromyography showed evidence of myopathic process with small amplitudes, polyphasic motor unit action potentials, and presence of pseudomyotonic discharges. Muscle biopsy showed glycogen-containing vacuoles in the muscle fibers consistent with glycogen storage disease. Genetic analysis revealed two compound heterozygous mutations at c.444C>G (p.Tyr148∗) in exon 2 and c.2238G>C (p.Trp746Cys) in exon 16, with the former being a novel mutation. This mutation has not been reported before, to our knowledge. The patient was treated with high protein diet during the admission and subsequently showed good clinical response to enzyme replacement therapy with survival now to the eighth year. Conclusion. In patients with late-onset adult Pompe's disease, careful evaluation and early identification of the disease and its treatment with high protein diet and enzyme replacement therapy improve muscle function and have beneficial impact on long term survival.
Fulltext Clinical, biochemical and mutational findings in biotinidase deficiency among Malaysian population

Mardhiah M, Azize NAA, Yakob Y, Affandi O, Hock NL, Rowani MR, et al.

Mol Genet Metab Rep, 2020 Mar;22:100548.
PMID: 32300527 DOI: 10.1016/j.ymgmr.2019.100548

Introduction: Biotinidase deficiency (BD) is an autosomal recessively inherited disorder characterized by developmental delay, seizures, hypotonia, ataxia, skin rash/eczema, alopecia, conjunctivitis/visual problem/optic atrophy and metabolic acidosis. Delayed diagnosis may lead to irreversible neurological damage.
Methodology: Clinically suspected patients were screened for biotinidase level by a fluorometry method. Profound BD patients were confirmed by mutation analysis of BTD gene.
Results: 9 patients had biotinidase activity of less than 77 U. 3 patients (33%) had profound BD while 6 patients (67%) had partial BD. Compound heterozygous mutations were detected at c.98_104delinsTCC p.(Cys33Phefs*36) in Exon 2 and c.833T>C p.(Leu278Pro) in Exon 4 in two patients and a homozygous mutation at c.98_104delinsTCC p.(Cys33Phefs*36) in Exon 2 in another patient.
Conclusion: Correct diagnosis lead to early treatment and accurate management of patient. Biochemical screening of BD in symptomatic child is prerequisite to determine enzyme status however molecular confirmation is vital in differentiating individuals with profound biotinidase deficiency from partial biotinidase deficiency and also individuals' carriers.
Fulltext Molecular analysis of fragile X syndrome (FXS) among Malaysian patients with developmental disability

Ali EZ, Yakob Y, Md Desa N, Ishak T, Zakaria Z, Ngu LK, et al.

Malays J Pathol, 2017 08;39(2):99-106.
PMID: 28866690 MyJurnal

Fragile X syndrome (FXS) is a neurodevelopmental disorder commonly found worldwide, caused by the silencing of fragile X mental retardation 1 (FMR1) gene on the X-chromosome. Most of the patients lost FMR1 function due to an expansion of cytosine-guanine-guanine (CGG) repeat at the 5' untranslated region (5'UTR) of the gene. The purpose of this study is to identify the prevalence of FXS and characterize the FMR1 gene CGG repeats distribution among children with developmental disability in Malaysia. Genomic DNA of 2201 samples from different ethnicities (Malays, Chinese, Indian and others) of both genders were PCR-amplified from peripheral blood leukocytes based on specific primers at 5'UTR of FMR1 gene. Full mutations and mosaics were successfully identified by triple methylation specific PCR (ms-PCR) and subsequently verified with FragilEase kit. The findings revealed for the first time the prevalence of FXS full mutation in children with developmental disability in Malaysia was 3.5%, a slightly higher figure as compared to other countries. Molecular investigation also identified 0.2% and 0.4% probands have permutation and intermediate alleles, respectively. The CGG repeats length observation showed 95% of patients had normal alleles within 11 to 44 CGG repeats; with 29 repeats found most common among Malays and Indians while 28 repeats were most common among Chinese. In conclusion, this is the first report of prevalence and characterisation of CGG repeats that reflects genetic variability among Malaysian ethnic grouping.
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.
Fulltext Molecular, Biochemical, and Clinical Characterization of Thirteen Patients with Glycogen Storage Disease 1a in Malaysia

Abdul Wahab SA, Yakob Y, Mohd Khalid MKN, Ali N, Leong HY, Ngu LH

Genet Res (Camb), 2022;2022:5870092.
PMID: 36160031 DOI: 10.1155/2022/5870092

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 G6PC 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.
METHODS: The information about 13 clinically classified GSD1a patients was retrospectively studied. The G6PC mutation analysis was performed by PCR-DNA sequencing.
RESULTS: Patients were presented with hepatomegaly (92%), hypoglycaemia (38%), poor weight gain (23%), and short stature (15%). Mutation analysis revealed nine heterozygous mutations; eight previously reported mutations (c.155 A > T, c.209 G > A, c.226 A > T, c.248 G > A, c.648 G > T, c.706 T > A, c.1022 T > A, c.262delG) and a novel mutation (c.325 T > C). The most common mutation found in Malaysian patients was c.648 G > T in ten patients (77%) of mostly Malay ethnicity, followed by c.248 G > A in 4 patients of Chinese ethnicity (30%). A novel missense mutation (c.325 T > C) was predicted to be disease-causing by various in silico software.
CONCLUSIONS: The establishment of G6PC molecular genetic testing will enable the detection of presymptomatic patients, assisting in genetic counselling while avoiding the invasive methods of liver biopsy.
Carbamoylphosphate synthetase 1 (CPS1) deficiency: clinical, biochemical, and molecular characterization in Malaysian patients

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.
Fulltext Clinical and Mutational Analysis of the GCDH Gene in Malaysian Patients with Glutaric Aciduria Type 1

Abdul Wahab SA, Yakob Y, Abdul Azize NA, Md Yunus Z, Huey Yin L, Mohd Khalid MK, et al.

Biomed Res Int, 2016;2016:4074365.
PMID: 27672653

Glutaric aciduria type 1 (GA1) is an autosomal recessive metabolic disorder caused by deficiency of glutaryl-CoA dehydrogenase enzyme encoded by the GCDH gene. In this study, we presented the clinical and molecular findings of seven GA1 patients in Malaysia. All the patients were symptomatic from infancy and diagnosed clinically from large excretion of glutaric and 3-hydroxyglutaric acids. Bidirectional sequencing of the GCDH gene revealed ten mutations, three of which were novel (Gln76Pro, Glu131Val, and Gly390Trp). The spectrum of mutations included eight missense mutations, a nonsense mutation, and a splice site mutation. Two mutations (Gln76Pro and Arg386Gln) were homozygous in two patients with parental consanguinity. All mutations were predicted to be disease causing by MutationTaster2. In conclusion, this is the first report of both clinical and molecular aspects of GA1 in Malaysian patients. Despite the lack of genotype and phenotype correlation, early diagnosis and timely treatment remained the most important determinant of patient outcome.
Spectrum of germ-line RB1 gene mutations in Malaysian patients with retinoblastoma

Mohd Khalid MK, Yakob Y, Md Yasin R, Wee Teik K, Siew CG, Rahmat J, et al.

Mol Vis, 2015;21:1185-90.
PMID: 26539030

The availability of molecular genetic testing for retinoblastoma (RB) in Malaysia has enabled patients with a heritable predisposition to the disease to be identified, which thus improves the clinical management of these patients and their families. In this paper, we presented our strategy for performing molecular genetic testing of the RB1 gene and the findings from our first 2 years of starting this service.
Fulltext Methanolic Extract of Clinacanthus nutans Exerts Antinociceptive Activity via the Opioid/Nitric Oxide-Mediated, but cGMP-Independent, Pathways

Abdul Rahim MH, Zakaria ZA, Mohd Sani MH, Omar MH, Yakob Y, Cheema MS, et al.

Evid Based Complement Alternat Med, 2016;2016:1494981.
PMID: 27190528 DOI: 10.1155/2016/1494981

The objectives of the present study were to determine the mechanisms of antinociceptive effect of methanol extract of Clinacanthus nutans (Acanthaceae) leaves (MECN) using various animal nociceptive models. The antinociceptive activity of orally administered 10% DMSO, 100 mg/kg acetylsalicylic acid (ASA), 5 mg/kg morphine, or MECN (100, 250, and 500 mg/kg) was determined using the acetic acid-induced abdominal constriction (ACT), formalin-induced paw licking (FT), and hot plate tests (HPT). The role of opioid and nitric oxide/cyclic guanosine monophosphate (NO/cGMP) systems was also investigated. The results showed that MECN produced a significant (p < 0.05) antinociceptive response in all nociceptive models with the recorded ED50 value of 279.3 mg/kg for the ACT, while, for the early and late phases of the FT, the value was >500 mg/kg or 227.7 mg/kg, respectively. This antinociceptive activity was fully antagonized by naloxone (a nonselective opioid antagonist) but was partially reversed by l-arginine (l-arg; a nitric oxide [NO] precursor), Nω-nitro-l-arginine methyl ester hydrochloride (l-NAME; an NO synthase inhibitor), or their combinations thereof. In contrast, 1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one (ODQ; a soluble guanylyl cyclase inhibitor) enhanced the extract's antinociception. UHPLC analysis revealed the presence of several flavonoid-based compounds with antinociceptive action. In conclusion, MECN exerted the peripherally and centrally mediated antinociceptive activity via the modulation of the opioid/NO-mediated, but cGMP-independent, systems.
Progressive ataxia, ophthalmoparesis, and hypogonadotropic hypogonadism in a family with a novel variant in the KIFBP gene

Ooi JCE, Azman A, Chan MY, Toh ESY, Seo GH, Kim JH, et al.

Clin Genet, 2024 Feb;105(2):228-230.
PMID: 37903629 DOI: 10.1111/cge.14448

A novel homozygous variant in KIFBP was identified in a consanguineous family with four sibs affected by Goldberg-Sphrintzen Syndrome (GOSHS). We report for the first time, early-adulthood-onset progressive ataxia, opthalmoparesis, and hypogonadotropic hypogonadism in GOSHS.
Fulltext Frequency of Spinocerebellar Ataxia type 1, 2, 3,6 and 7 and clinical profile of Spinocerebellar Ataxia type 3 in Malaysia

Mohamed Ibrahim N, Lau YH, Ariffin N, Md Desa SH, Azizan E, Chin LK, et al.

Cerebellum & ataxias, 2020;7:11.
PMID: 32922823 DOI: 10.1186/s40673-020-00120-2

Spinocerebellar ataxias (SCA) are highly heterogenous group of neurodegenerative diseases causing progressive cerebellar dysfunction. We report the first description of relative frequencies of the common SCA mutations and of phenotypic characteristics of SCA3 patients among Malaysians. Pooled data from adult Malaysian patients who had undergone genetic testing for SCA 1,2,3,6 and 7 at UKM Medical Centre and Institute for Medical Research from 2017 to 2020 were analysed. Fifteen patients with SCA 3 had detailed clinical phenotype evaluation using Inventory for Non -Ataxia Signs (INAS) and Ataxia Severity evaluation using the Scale for Assessment and Rating of Ataxia (SARA). Out of 152 adults patients who were tested for common SCA mutations, 64(42.1%) patients were tested positive for either SCA 1,2,3,6 or 7. Of the 64 positive cases, 44 (68.9%) patients were diagnosed with SCA 3 followed by SCA 2 in 13(20.3%) patients and SCA 1 in 5 (7.8%) patients. Our findings suggest that Malay race had the highest frequency of SCA (n = 34, 50%), followed by the Chinese (n = 16, 23.5%) and approximately 60 (93.8%) SCA patients had first degree family history. In conclusion, SCA 3 is the commonest SCA in Malaysia, followed by SCA 2 and SCA 1. It is important to develop a proper registry of SCA patients to further understand the true prevalence and local impact of the disease in Malaysia.
Fulltext Novel mutations associated with carnitine-acylcarnitine translocase and carnitine palmitoyl transferase 2 deficiencies in Malaysia

Habib A, Azize NAA, Rahman SA, Yakob Y, Suberamaniam V, Nazri MIBA, et al.

Clin Biochem, 2021 Dec;98:48-53.
PMID: 34626609 DOI: 10.1016/j.clinbiochem.2021.10.002

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. We reviewed medical records of six patients diagnosed with CACT and CPT2 deficiencies. They were identified from a selective high-risk screening of 50,579 patients from January 2010 until Jun 2020.
RESULTS: All six patients had either elevation of the long chain acylcarnitines and/or an elevated (C16 + C18:1)/C2 acylcarnitine ratio. SLC25A20 gene sequencing of patient 1 and 6 showed a homozygous splice site mutation at c.199-10 T > G in intron 2. Two novel mutations at c.109C > T p. (Arg37*) in exon 2 and at c.706C > T p. (Arg236*) in exon 7 of SLC25A20 gene were found in patient 2. Patient 3 and 4 (siblings) exhibited a compound heterozygous mutation at c.638A > G p. (Asp213Gly) and novel mutation c.1073 T > G p. (Leu358Arg) in exon 4 of CPT2 gene. A significant combined prevalence at 0.01% of CACT and CPT2 deficiencies was found in the symptomatic Malaysian patients.
CONCLUSIONS: The use of the (C16 + C18:1)/C2 acylcarnitine ratio in dried blood spot in our experience improves the diagnostic specificity for CACT/CPT2 deficiencies over long chain acylcarnitine (C16 and C18:1) alone. DNA sequencing for both genes aids in confirming the diagnosis.
Fulltext Genotype, phenotype and treatment outcomes of 17 Malaysian patients with infantile-onset Pompe disease and the identification of 3 novel GAA variants

Chan MY, Jalil JA, Yakob Y, Wahab SAA, Ali EZ, Khalid MKNM, et al.

Orphanet J Rare Dis, 2023 Aug 04;18(1):231.
PMID: 37542277 DOI: 10.1186/s13023-023-02848-6

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. This study aims to describe the clinical and molecular spectrum of Malaysian IOPD patients, and to analyze their long term treatment outcomes.
METHODS: Seventeen patients diagnosed with IOPD between 2000 and 2020 were included in this retrospective cohort study. Clinical and biochemical data were collated and analyzed using descriptive statistics. GAA enzyme levels were performed on dried blood spots. Molecular analysis of the GAA gene was performed by polymerase chain reaction and Sanger sequencing. Structural modelling was used to predict the effect of the novel mutations on enzyme structure.
RESULTS: Our cohort had a median age of presentation of 3 months and median age of diagnosis of 6 months. Presenting features were hypertrophic cardiomyopathy (100%), respiratory insufficiency (94%), hypotonia (88%), failure to thrive (82%), feeding difficulties (76%), and hepatomegaly (76%). Fourteen different mutations in the GAA gene were identified, with three novel mutations, c.1552-14_1552-1del, exons 2-3 deletion and exons 6-10 deletion. The most common mutation identified was c.1935C > A p.(D645E), with an allele frequency of 33%. Sixteen patients received ERT at the median age of 7 months. Overall survival was 29%. Mean age of death was 17.5 months. Our longest surviving patient has atypical IOPD and is currently 20 years old.
CONCLUSIONS: This is the first study to analyze the genotype and phenotype of Malaysian IOPD patients, and has identified the c.1935C > A p.(D645E) as the most common mutation. The three novel mutations reported in this study expands the mutation spectrum for IOPD. Our low survival rate underscores the importance of early diagnosis and treatment in achieving better treatment outcomes.
Fulltext Performance comparison of EasyFix G26 and HYDRASYS 2 SCAN for the detection of serum monoclonal proteins

Amin Nordin FD, Mohd Khalid MKN, Abdul Aziz SM, Mohamad Bakri NA, Ahmad Ridzuan SN, Abdul Jalil J, et al.

J Clin Lab Anal, 2020 Jun;34(6):e23254.
PMID: 32141626 DOI: 10.1002/jcla.23254

BACKGROUND: Serum protein electrophoresis (SPE) is a widely used laboratory technique to diagnose patients with multiple myeloma (MM) and other disorders related to serum protein. In patients with MM, abnormal monoclonal protein can be detected by SPE and further characterized using immunofixation electrophoresis (IFE). There are several semi-automated agarose gel-based systems available commercially for SPE and IFE. In this study, we sought to evaluate the analytical performance of fully automated EasyFix G26 (EFG26) and semi-automated HYDRASYS 2 SCAN (H2SCAN) for both SPE and IFE.
METHODS: Both instruments were operated according to manufacturer's instructions. Samples used include a commercially available normal control serum (NCS) and patients' specimens. The following were evaluated: precision and comparison studies for SPE, and reproducibility and comparison studies for IFE. Statistical analyses were performed using Microsoft Excel.
RESULTS: For SPE repeatability study, our results showed that EFG26 has higher coefficient of variation (%CV) compared with H2SCAN for both samples except for monoclonal component with %CV of 0.97% and 1.18%, respectively. Similar results were obtained for SPE reproducibility study except for alpha-1 (4.16%) and beta (3.13%) fractions for NCS, and beta fractions (5.36%) for monoclonal sample. Subsequently, reproducibility for IFE was 100% for both instruments. Values for correlation coefficients between both instruments ranged from 0.91 to 0.98 for the five classic bands.
CONCLUSION: Both instruments demonstrated good analytical performance characterized by high precision, reproducibility and correlation.
Fulltext Clinical, biochemical and genetic profiles of patients with mucopolysaccharidosis type IVA (Morquio A syndrome) in Malaysia: the first national natural history cohort study

Leong HY, Abdul Azize NA, Chew HB, Keng WT, Thong MK, Mohd Khalid MKN, et al.

Orphanet J Rare Dis, 2019 06 14;14(1):143.
PMID: 31200731 DOI: 10.1186/s13023-019-1105-6

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.
METHODS: This is a multicentre descriptive case series of 21 patients comprising all MPS IVA patients in Malaysia. Mutational analysis was performed by PCR and Sanger sequencing of the GALNS gene in 17 patients.
RESULTS: The patients (15 females and 6 males) had a mean age (± SD) of 15.5 (± 8.1) years. Mean age at symptom onset was 2.6 (± 2.1) years and at confirmed diagnosis was 6.9 (± 4.5) years. The study cohort included patients from all the main ethnic groups in Malaysia - 57% Malay, 29% Chinese and 14% Indian. Common presenting symptoms included pectus carinatum (57%) and genu valgum (43%). Eight patients (38%) had undergone surgery, most commonly knee surgeries (29%) and cervical spine decompression (24%). Patients had limited endurance with lower mean walking distances with increasing age. GALNS gene analysis identified 18 distinct mutations comprising 13 missense, three nonsense, one small deletion and one splice site mutation. Of these, eight were novel mutations (Tyr133Ser, Glu158Valfs*12, Gly168*, Gly168Val, Trp184*, Leu271Pro, Glu320Lys, Leu508Pro). Mutations in exons 1, 5 and 9 accounted for 51% of the mutant alleles identified.
CONCLUSIONS: All the MPS IVA patients in this study had clinical impairments. A better understanding of the natural history and the clinical and genetic spectrum of MPS IVA in this population may assist early diagnosis, improve management and permit timely genetic counselling and prenatal diagnosis.
Fulltext Prevalence of DDC genotypes in patients with aromatic L-amino acid decarboxylase (AADC) deficiency and in silico prediction of structural protein changes

Himmelreich N, Bertoldi M, Alfadhel M, Alghamdi MA, Anikster Y, Bao X, et al.

Mol Genet Metab, 2023 Jul;139(3):107624.
PMID: 37348148 DOI: 10.1016/j.ymgme.2023.107624

Aromatic L-amino acid decarboxylase (AADC) deficiency is a rare autosomal recessive genetic disorder affecting the biosynthesis of dopamine, a precursor of both norepinephrine and epinephrine, and serotonin. Diagnosis is based on the analysis of CSF or plasma metabolites, AADC activity in plasma and genetic testing for variants in the DDC gene. The exact prevalence of AADC deficiency, the number of patients, and the variant and genotype prevalence are not known. Here, we present the DDC variant (n = 143) and genotype (n = 151) prevalence of 348 patients with AADC deficiency, 121 of whom were previously not reported. In addition, we report 26 new DDC variants, classify them according to the ACMG/AMP/ACGS recommendations for pathogenicity and score them based on the predicted structural effect. The splice variant c.714+4A>T, with a founder effect in Taiwan and China, was the most common variant (allele frequency = 32.4%), and c.[714+4A>T];[714+4A>T] was the most common genotype (genotype frequency = 21.3%). Approximately 90% of genotypes had variants classified as pathogenic or likely pathogenic, while 7% had one VUS allele and 3% had two VUS alleles. Only one benign variant was reported. Homozygous and compound heterozygous genotypes were interpreted in terms of AADC protein and categorized as: i) devoid of full-length AADC, ii) bearing one type of AADC homodimeric variant or iii) producing an AADC protein population composed of two homodimeric and one heterodimeric variant. Based on structural features, a score was attributed for all homodimers, and a tentative prediction was advanced for the heterodimer. Almost all AADC protein variants were pathogenic or likely pathogenic.

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