Birth defects or congenital anomalies are one of the major causes of disability in developed and developing countries. Data on birth defects from population-based studies originating from developing countries are lacking. Increasingly, there is a shift to genetic testing and genomics study of birth defects. However, the translation from bench findings to bedside medicine has been muted. There is a need to address this imbalance where congenital anomalies remained the top etiology for neonatal mortality in developing countries. To build capacity in low resource countries, there is a need for accurate collection and ascertainment of birth defects in developing countries. The systematic collection and analysis of data on major birth defects using birth defects registries (BDRs) are an integral part of all clinical genetic services. Healthcare planners in developing countries must be aware of the advantages and limitations of BDRs. Despite the advent of the genomics era, BDRs are essential to the planning and developing care and prevention services at local and national levels, particularly in low resource or developing countries.
The story of clinical genetics is a relatively new one, first spearheaded by paediatrics but increasingly, has taken root in all branches of medicine leading to ‘personalised medicine’. There are expectations that this revolution in genetics will pave the way to genomic medicine and a cure for all inherited disorders. The development of the field of Clinical Genetics and genetic counselling in Malaysia is still in its infancy. Using evidence-based data on genetic disorders such as birth defects, inborn errors of metabolism, genetic syndromes, neurological disorders and hereditary cancers, that hitherto have not been well documented in Malaysia, this review article will focus on findings and issues that will present a unique insight and opportunity to understanding the complex genetic counselling issues related to clinical genetics in Malaysia.
The United Nations General Assembly adopted the 2030 Agenda for Sustainable Development in November 2015 which included a set of 17 measurable "sustainable development goals" (SDGs). The SDGs included targets to end preventable deaths of newborns and children under 5 years of age by 2030, universal health care coverage, reduction of premature mortality from noncommunicable diseases (NCDs) by 33% as well as support the development and research for medicines for both communicable and NCDs. Although some successes were achieved in combating communicable diseases and improved childhood mortality rates, health systems in Asia are generally characterized by lack of accurate epidemiological information on congenital disorders, lack of human and financial resources, and inadequate focus on public health strategies to ensure targeted interventions, low level knowledge on congenital disorders amongst the community and healthcare providers and the ethical dilemma of managing rare congenital disorders in an environment of low national health expenditures. These bottlenecks must be addressed systematically and interventions such as the use of innovative epidemiological tools to overcome lack of data, increased efforts to standardize rare disease nomenclature and classification and renewed interest in birth defects registries by countries in the region must be considered. Targeted curative and public health approaches currently used in thalassaemia and neural tube defects may be used for other congenital disorders in Asian countries. The implementation of congenital disorders-related research, prevention, care, and treatment delivery services must be integrated into existing health systems in order to be effective to achieve the targets of SDG2030.
Genetic counseling service is urgently required in developing countries. In Malaysia, the first medical genetic service was introduced in 1994 at one of the main teaching hospitals in Kuala Lumpur. Two decades later, the medical genetic services have improved with the availability of genetic counseling, genetic testing and diagnosis, for both paediatric conditions and adult-onset inherited conditions, at four main centers of medical genetic services in Malaysia. Prenatal diagnosis services and assisted reproductive technologies are available at tertiary centres and private medical facilities. Positive developments include governmental recognition of Clinical Genetics as a subspecialty, increased funding for genetics services, development of medical ethics guidelines, and establishment of support groups. However, the country lacked qualified genetic counselors. Proposals were presented to policy-makers to develop genetic counseling courses. Challenges encountered included limited resources and public awareness, ethical dilemmas such as religious and social issues and inadequate genetic health professionals especially genetic counselors.
We report the first two Malaysian children with partial deletion 9p syndrome, a well delineated but rare clinical entity. Both patients had trigonocephaly, arching eyebrows, anteverted nares, long philtrum, abnormal ear lobules, congenital heart lesions and digital anomalies. In addition, the first patient had underdeveloped female genitalia and anterior anus. The second patient had hypocalcaemia and high arched palate and was initially diagnosed with DiGeorge syndrome. Chromosomal analysis revealed a partial deletion at the short arm of chromosome 9. Karyotyping should be performed in patients with craniostenosis and multiple abnormalities as an early syndromic diagnosis confers prognostic, counselling and management implications.
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.
Beta-thalassaemia major is one of the commonest genetic disorders in South East Asia. The strategy for the community control of beta-thalassaemia major requires the characterisation of the spectrum of beta-globin gene mutations in any multi-ethnic population. There is only a single report of mutation analyses of the beta-globin gene in an isolated Kadazandusun community in Kota Belud, Sabah, Malaysia, which showed the presence of a common 45 kb deletion.
We studied 253 women with a pregnancy complicated by a birth defect and 506 controls to determine the frequency and type of prenatal tests and the types of defects detected antenatally. Most women had at least one ultrasound examination, but the frequency of other screening tests was low. Only 38 (15%) of defects were detected antenatally (37 by ultrasound). Birth prevalence is unlikely to be affected by pregnancy termination.
The beta-thalassaemia mutations in 20 Malaysian children with beta-thalassaemia major were characterised by using a multi-modal approach, consisting of a slot-blot hybridisation with selected allele-specific oligonucleotides (ASO), followed by reverse dot-blot assay (RDB), amplification refractory mutation system (ARMS) and genomic sequencing. This strategy yielded a 94.4% mutation detection rate. The 6 most common mutations were codons 41/42 (-TTCT), IVS II nt 654(C --> T), IVS I nt 5(G --> C), IVS I nt 1(G -->T), codon 35 (-C) and codon 19 (A --> G), which accounted for 83.3% of all mutations detected. A strategy of initial screening with the above 6 selected ASOs for slot-blot hybridisation followed by RDB assay for the less common Asian mutations would give a mutation identification of 91.7%. Another feasible approach would be to analyse alleles from a particular racial group, by a judicious selection of 4 ASOs common to that particular subpopulation and then supplement this with RDB assay. This could yield a 100% coverage for the Chinese subpopulation in Malaysia. With these strategies, a practical approach has been identified to overcome the pitfalls posed by the molecular heterogeneity of beta-thalassaemia to enable prenatal diagnosis and carrier screening to be carried out. Regional collaborative studies are to be encouraged as an indispensable tool in providing better health care services to our patients.
The finding of a supernumerary or marker chromosome in a karyotype poses difficulty in genetic counselling. The true incidence and significance of this chromosomal aberration is unknown in Malaysia. We report two patients who presented with supernumerary chromosomes in mosaic Turner syndrome.
Birth defects are one of the leading causes of paediatric disability and mortality in developed and developing countries. Data on birth defects from population-based studies originating from developing countries are lacking. One of the objectives of this study was to determine the epidemiology of major birth defects in births during the perinatal period in Kinta district, Perak, Malaysia over a 14-month period, using a population-based birth defect register. There were 253 babies with major birth defects in 17,720 births, giving an incidence of 14.3/1000 births, a birth prevalence of 1 in 70. There were 80 babies with multiple birth defects and 173 with isolated birth defects. The exact syndromic diagnosis of the babies with multiple birth defects could not be identified in 18 (22.5%) babies. The main organ systems involved in the isolated birth defects were cardiovascular (13.8%), cleft lip and palate (11.9%), clubfeet (9.1%), central nervous system (CNS) (including neural tube defects) (7.9%), musculoskeletal (5.5%) and gastrointestinal systems (4.7%), and hydrops fetalis (4.3%). The babies with major birth defects were associated with lower birth weights, premature deliveries, higher Caesarean section rates, prolonged hospitalization and increased specialist care. Among the cohort of babies with major birth defects, the mortality rate was 25.2% during the perinatal period. Mothers with affected babies were associated with advanced maternal age, birth defects themselves or their relatives but not in their other offspring, and significantly higher rates of previous abortions. The consanguinity rate of 2.4% was twice that of the control population. It is concluded that a birth defects register is needed to monitor these developments and future interventional trials are needed to reduce birth defects in Malaysia.
Distal renal tubular acidosis (RTA) and hereditary elliptocytosis (HE) are apparently distinct, genetic conditions. We report a family with 3 children having both hereditary elliptocytosis and distal renal tubular acidosis. The simultaneous occurrence of these two conditions in three siblings could be due to covariations in the same family, although a possible contiguous gene syndrome for distal RTA and HE cannot be excluded. This report emphasises the importance of excluding a renal tubular defect in any child who presents with elliptocytosis and failure to thrive.
We report the occurrence of X-linked lymphoproliferative disease (XLP) in two brothers in a Malaysian family. In this disorder, a primary Epstein-Barr virus (EBV) infection is followed by an abnormal proliferation of transformed B-cells that cannot be controlled by suppressor T-cells, leading to the development of deranged immune function. This results in fatal infectious mononucleosis, acquired hypogammaglobulinaemia, virus-infected haemophagocytic syndrome and non-Hodgkin's lymphoma. The diagnosis should be considered when there is a family history of any male having a fulminant course of infectious mononucleosis, an otherwise benign disease. Early diagnosis is important as bone marrow transplantation is the only curative option in this disorder.
ESCO2 spectrum disorder is an autosomal recessive developmental disorder characterized by growth retardation, symmetrical mesomelic limb malformation, and distinctive facies with microcephaly, with a wide phenotypic continuum that ranges from Roberts syndrome (MIM #268300) at the severe end to SC phocomelia (MIM #269000) at the milder end. ESCO2 encodes a 601-amino acid protein belonging to the Eco1/Ctf7 family of acetyltransferases that is involved in the establishment of sister chromatid cohesion, which is essential for accurate chromosome segregation and genomic stability and thus belongs to a group of disorders called "cohesinopathies". We describe a 15-year-old Malaysian female who presented with the characteristic triad of ESCO2 spectrum disorder, with an equivocal chromosomal breakage study and normal karyotyping findings. She was initially suspected to have mosaic Fanconi anemia but whole exome sequencing (WES) showed a likely pathogenic homozygous splice variant c.955 + 2_955+5del in the ESCO2 gene. During the 15-year diagnostic odyssey, she developed type 2 diabetes mellitus, primary ovarian insufficiency, increased optic cup-to-disc ratio with tortuous vessels bilaterally, and an evolving but distinct facial and skin hypopigmentation phenotype. Of note, there was an absence of learning disabilities. Our findings provide further evidence for ESCO2 spectrum disorder in an Asian child and contribute to defining the clinical and radiographic spectrum.
This study aimed to determine the prevalence and early outcome of neural tube defects (NTDs) in Malaysia. This prospective study included all neonates with NTDs (spina bifida, anencephaly, encephalocoele) born in 2009 in 32 Malaysian hospitals in the Malaysian National Neonatal Network. The prevalence of NTDs was 0.42 per 1000 live births, being highest among the indigenous people of Sarawak (1.09 per 1000 live births) and lowest among Malaysians of Chinese descent (0.09 per 1000 live births). The most common type of NTDs was anencephaly (0.19 per 1000 live births), followed by spina bifida (0.11 per 1000 live births) and encephalocoele (0.07 per 1000 live births). Majority of the infants with anencephaly (94.5%, n = 51), 45.8% (n = 11) with encephalocoele and 9.5% (n = 4) with spina bifida died. The median duration of hospital stay was 4 (range: 0-161) days.
There are few reports of congenital disorders of glycosylation (CDGs) in the Asian population, although they have been reported worldwide. We identified a Malaysian infant female at 2 days of life with CDG type Ia. The diagnosis was suspected on the basis of inverted nipples and abnormal fat distribution. She had cerebellar hypoplasia and developed coagulopathy, hypothyroidism and severe pericardial effusion and died at 7 months of life. The diagnosis was supported by abnormal serum transferrin isoform pattern that showed elevated levels of the disialotransferrin isoform and trace levels of the asialotransferrin isoform. Enzyme testing of peripheral leukocytes showed decreased level of phosphomannomutase (PMM) activity (0.6 nmol/min per mg protein, normal range 1.6-6.2) and a normal level of phosphomannose isomerase activity (19 nmol/min per mg protein, normal range 12-25), indicating a diagnosis of CDG type Ia. Mutation study of the PMM2 gene showed the patient was heterozygous for both the common p.R141H (c.422T>A) mutation and a novel sequence change in exon 7, c.618C>A. The latter change is predicted to result in the replacement of the highly conserved phenylalanine residue at position 206 with a leucine residue (p.F206L) and occurs in the same codon as the previously reported p.F206S mutation. Analysis of 100 control chromosomes has shown that the p.F206L sequence change is not present, making it highly likely that this change is functionally important. To the best of our knowledge, this is the first report of CDG in the Malay population. Prenatal diagnosis was successfully performed in a subsequent pregnancy for this family.
Clinical data on Duchenne muscular dystrophy (DMD) are lacking in developing countries. The objective of this study was to delineate the demographic characteristics, investigations, and outcome of 21 Malaysian males diagnosed with DMD over a period of 10 years. Mean age presentation was 3 years 8 months (SD 23mo; range 10 to 84mo), mean duration from first presentation to diagnosis was 3y 7mo (SD 26mo; range 5 to 84) and the mean age for loss of ambulation was 11 years (SD 25mo; range 102 to 168). There was family history of DMD in five of the 21 patients. Muscle biopsy showed confirmatory findings of DMD in the 16 patients tested. Molecular genetic analysis showed dystrophin gene deletions in 11 of these 16 patients. Four and seven of the students stopped schooling and had learning difficulties, respectively; only nine had satisfactory school performances. Eight out of 14 patients evaluated were classified as having severe to total dependency levels on the modified Barthel Index for activities of daily living assessment. DMD is associated with significant medical and social needs for a developing country such as Malaysia. Earlier referral, genetic counselling, and provision of support and rehabilitative services are the main priorities.