Urine organic acid as the first clue towards aromatic L-amino acid decarboxylase (AADC) deficiency in a high prevalence area.

Background: Aromatic L-amino acid decarboxylase deficiency is a rare neurometabolic disease due to impaired decarboxylation of neurotransmitter precursors to its active form.

Case: We retrospectively reviewed 8 cases from 2008 to 2019 with cerebrospinal fluid neurotransmitter analysis performed at our centre. All cases had an elevated urine vanillactic acid and, in most cases, with N-acetylvanilalanine detected.

Clinical and pathological characterization of FLNC-related myofibrillar myopathy caused by founder variant c.8129G>A in Hong Kong Chinese.

FLNC-related myofibrillar myopathy could manifest as autosomal dominant late-onset slowly progressive proximal muscle weakness; involvements of cardiac and/or respiratory functions are common. We describe 34 patients in nine families of FLNC-related myofibrillar myopathy in Hong Kong ethnic Chinese diagnosed over the last 12 years, in whom the same pathogenic variant c.8129G>A (p.

NMR-based urinalysis for rapid diagnosis of β-ureidopropionase deficiency in a patient with Dravet syndrome.

Background: Beta-ureidopropionase deficiency is a rare inborn error of metabolism (IEM) affecting pyrimidine metabolism. To-date, about 30 genetically confirmed cases had been reported. The clinical phenotypes of this condition are variable; some patients were asymptomatic while some may present with developmental delay or autistic features.

2,4-Dinitrophenol: a threat to Chinese body-conscious groups.

2,4-Dinitrophenol (2,4-DNP), a yellowish compound, has historically been used in the manufacture of dyes, explosives, and fungicides. As it uncouples mitochondrial oxidative phosphorylation, the compound was also used as an antiobesity agent early in the past century. The compound was subsequently banned by the United States Food and Drug Administration in 1938 due to its potentially fatal adverse effects, including hyperthermia, cataract, agranulocytosis, hepatoxicity, nephrotoxicity, and cardiotoxicity.

Inborn errors of metabolism and expanded newborn screening: review and update.

Inborn errors of metabolism (IEM) are a phenotypically and genetically heterogeneous group of disorders caused by a defect in a metabolic pathway, leading to malfunctioning metabolism and/or the accumulation of toxic intermediate metabolites. To date, more than 1000 different IEM have been identified. While individually rare, the cumulative incidence has been shown to be upwards of 1 in 800.

Simultaneous detection of 22 toxic plant alkaloids (aconitum alkaloids, solanaceous tropane alkaloids, sophora alkaloids, strychnos alkaloids and colchicine) in human urine and herbal samples using liquid chromatography-tandem mass spectrometry.

A liquid chromatography-tandem mass spectrometry method for simultaneous detection of 22 toxic plant alkaloids, including aconitum alkaloids and their hydrolyzed products (aconitine, hypaconitine, mesaconitine, yunaconitine, crassicauline A, benzoylaconine, benzoylmesaconine, benzoylhypaconine, deacetylyunaconitine, deacetylcrassicauline A), solanaceous tropane alkaloids (atropine, anisodamine, scopolamine, anisodine), sophora alkaloids (matrine, sophoridine, oxymatrine, cytisine, N-methylcytisine), strychnos alkaloids (brucine, strychnine) and colchicine, in herbal and urine samples was developed and validated. Following sample preparation by liquid-liquid extraction, chromatographic separation was achieved on Eclipse XDB C8 column. Identification was based on two multiple reaction monitoring transitions and the relative ion intensity.

Hyperekplexia: a Chinese adolescent with 2 novel mutations of the GLRA1 gene.

Hyperekplexia is a rare neurologic disorder, characterized by excessive startle response to unexpected stimuli. There are 3 cardinal features: generalized stiffness immediately after birth that normalizes during the first year of life; excessive startle reflex to unexpected (particularly auditory) stimuli; and a short period of generalized stiffness following the startle response while patient cannot elicit voluntary movements. Awareness of this condition will avoid misdiagnosis of disorders like epilepsy.

Electronic chemical pathology consultation service and dried blood spot metabolic screening in hospital patients.

Aim: Inborn errors of metabolism (IEM) are an unpopular and difficult subject and most clinicians are unfamiliar with them. Although chemical pathologists have a long-standing practice in advising test strategy and result interpretation especially from primary care, such consultations are usually informal, unstructured and those related to IEM are infrequently requested. This study aims to provide a formal electronic consultation service and to apply tandem mass spectrometry-based dried blood spot metabolic screening (DBSM) as a rapid first-line test for patients suspected of IEM.

Molecular diagnosis for a fatal case of very long-chain acyl-CoA dehydrogenase deficiency in Hong Kong Chinese with a novel mutation: a preventable death by newborn screening.

Very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency is one of the most common fatty acid oxidation defects that cause sudden unexpected deaths in infants. The death attributed to VLCAD deficiency can be prevented by early diagnosis with expanded newborn screening using tandem mass spectrometry. A favorable outcome can be achieved with early diagnosis and prompt treatment.

Aconite poisoning over 5 years: a case series in Hong Kong and lessons towards herbal safety.

Background: Aconite poisoning is a severe, life-threatening poisoning related to the use of traditional Chinese medicine (TCM). Despite current legislation, repeated poisoning cases are steadily encountered.

Objective: The aim of the study was to summarize the clinical features and to elucidate the causative and contributory factors leading to aconite poisoning.

A case of early-onset obesity, hypocortisolism, and skin pigmentation problem due to a novel homozygous mutation in the proopiomelanocortin (POMC) gene in an Indian boy.

Proopiomelanocortin (POMC) is the polypeptide precursor of several biologically active melanocortin peptides that have important roles in the regulation of food intake and energy homeostasis, adrenal steroidogenesis, melanocyte stimulation, and immune modulation. Mutation of the POMC gene has been associated with adrenal insufficiency, early-onset obesity, and red hair pigmentation. We describe an Indian boy with secondary hypocortisolism, hyperphagia, early-onset obesity, and skin pigmentation problem.

Personalized medicine switching from insulin to sulfonylurea in permanent neonatal diabetes mellitus dictated by a novel activating ABCC8 mutation.

Background: Neonatal diabetes mellitus (NDM) is a rare but important condition affecting approximately 1 in 100,000 newborns. Permanent form requires life-long treatment with difficulties in long-term compliance and metabolic complications. Exact genetic diagnosis can enable improved outcome and patient satisfaction by switching insulin injection to oral sulfonylureas.

Non-invasive urinary screening for aromatic L-amino acid decarboxylase deficiency in high-prevalence areas: a pilot study.

Background: The diagnosis of aromatic L-amino acid decarboxylase (AADC) deficiency, one of the pediatric neurotransmitter disorders, is classically made with plasma enzyme level or cerebrospinal fluid (CSF) neurotransmitter profile, while both are technically demanding and the latter requires the invasive lumbar puncture. So far less than 100 cases have been reported worldwide with 20% from Taiwan. It was postulated that the condition might have been under-diagnosed among Chinese populations and a non-invasive screening tool should be developed in areas with high prevalence.

Phenylketonuria in Hong Kong Chinese: a call for hyperphenylalaninemia newborn screening in the Special Administrative Region, China.

Hyperphenylalaninemia is one of the commonest inborn errors of metabolism affecting approximately 1 in 15,000 livebirths. Among Chinese, BH4 deficiency leading to hyperphenylalaninemia is much commoner than in Caucasians. Exact diagnosis is important for the treatment and genetic counseling.

Novel nonsense CDC73 mutations in Chinese patients with parathyroid tumors.

Hyperparathyroidism-jaw tumor syndrome (HPT-JT) is an autosomal dominant disease characterized by the occurrences of parathyroid tumors and ossifying fibroma of maxilla/mandible. It is caused by mutations in CDC73 gene and mutation carriers are at increased risk of parathyroid carcinoma. Hyperparathyroidism could be the sole manifestation.

Fatal viral infection-associated encephalopathy in two Chinese boys: a genetically determined risk factor of thermolabile carnitine palmitoyltransferase II variants.

Influenza-associated encephalopathy (IAE) is a potentially fatal neurological complication of influenza infection usually in the presence of high and persistent fever. Thermolabile carnitine palmitoyltransferase II enzyme (CPT-II) predisposes IAE, so far only described in Japanese. As the genetic origins of Japanese and Chinese are alike, similar genetic risk factors in CPT-II are expected.

Analysis of inborn errors of metabolism: disease spectrum for expanded newborn screening in Hong Kong.

Background: Data of classical inborn errors of metabolism (IEM) of amino acids, organic acids and fatty acid oxidation are largely lacking in Hong Kong, where mass spectrometry-based expanded newborn screening for IEM has not been initiated. The current study aimed to evaluate the approximate incidence, spectrum and other characteristics of classical IEM in Hong Kong, which would be important in developing an expanded newborn screening program for the local area.

Methods: The laboratory records of plasma amino acids, plasma acylcarnitines and urine organic acids analyses from year 2005 to 2009 inclusive in three regional chemical pathology laboratories providing biochemical and genetic diagnostic services for IEM were retrospectively reviewed.

Molecular basis of von Hippel-Lindau syndrome in Chinese patients.

Background: Von Hippel-Lindau (VHL) syndrome is an autosomal dominant familial cancer syndrome predisposing the affected individuals to multiple tumours in various organs. The genetic basis of VHL in Southern Chinese is largely unknown. In this study, we characterized the mutation spectrum of VHL in nine unrelated Southern Chinese families.

Role of postmortem genetic testing demonstrated in a case of glutaric aciduria type II.

Glutaric aciduria type II, or multiple acyl-CoA dehydrogenase deficiency, is a rare metabolic disorder inherited in an autosomal recessive manner. The condition can be caused by mutations in at least 3 genes, including ETFA, ETFB, and ETFDH. When this potentially lethal disorder is known for its clinical and biochemical heterogeneity, mutation analysis will be an invaluable part of diagnosis.

Identification of a novel vardenafil analogue in herbal product.

A new herbal health product marketed for enhancing erectile function, namely Power58 Platinum, was purchased over-the-counter in Hong Kong. The product was tested for adulteration with sildenafil, tadalafil, and vardenafil as well as their structurally modified analogues. A new analogue of vardenafil, in which the N-ethylpiperazine ring and the sulphonyl group were removed from the vardenafil structure, was identified in the product.

Mitochondrial DNA deletion in a girl with Fanconi's syndrome.

We report a sporadic large-scale mitochondrial deletion in a paediatric patient with Fanconi's syndrome. Renal biopsy disclosed chronic interstitial nephritis. Ultrastructural examination of the renal tissue showed many giant atypical mitochondria.

A novel mutation (C271F) in the Notch3 gene in a Chinese man with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.

Background: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an adult-onset hereditary condition caused by mutations in the Notch3 gene. A Chinese man was studied.

Method: Electronic microscopy examination of skin biopsy.

Risk of vitamin A toxicity from candy-like chewable vitamin supplements for children.

Numerous vitamin supplements are available over-the-counter to the general public. Some such supplements are available as candy-like chewable preparations to encourage consumption by children. We report 3 cases of overdose of such preparations.