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.

Novel PPOX exonic mutation inducing aberrant splicing in a patient with homozygous variegate porphyria.

Introduction: Variegate porphyria (VP; OMIM 176200) is one of the acute hepatic porphyrias, and it is characterized by the partial deficiency of protoporphyrinogen oxidase (PPOX). The unusual homozygous variant with mutations on both alleles of PPOX is distinguished with general heterozygous VP by several typical points such as severe defect in PPOX enzyme activity, early onset of photosensitivity before puberty, and skeletal deformity.

Material And Method: In this study, we describe a very rare case of autosomal recessive form of true homozygous VP found in a Chinese patient with consanguineous parents.

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.

NMR-based urinalysis for beta-ketothiolase deficiency.

Background: Beta-ketothiolase deficiency is a rare inborn errors of metabolism (IEM) affecting the catabolism of isoleucine, characterized by severe ketoacidosis in children of 6 to 24months old. A prompt diagnosis is of paramount importance as the metabolic decompensation can be effectively reverted by glucose infusion and health outcomes are improved on a protein-restricted diet. Currently, majority of the laboratory diagnosis were made based on mass-spectrometry and molecular genetics while little is mentioned on the advancement of nuclear magnetic resonance (NMR) spectroscopy for the diagnosis of this condition.

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.

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.

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.

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.

Confirmation of gelsemium poisoning by targeted analysis of toxic gelsemium alkaloids in urine.

The gelsemium plants are highly poisonous but toxicological evaluation of suspected poisoning cases has been hampered by the chemical complexity of the gelsemium toxins involved. A novel liquid chromatography-tandem mass spectrometry protocol was optimized for the collective detection of gelsemine and related alkaloids from Gelsemium elegans. The screening protocol was applied to the clinical investigation of unexplained intoxications following the ingestion of seemingly nontoxic herbs.

Hepatitis induced by Teucrium viscidum.

Introduction: In Hong Kong, Chinese medicine is popular and coexists with orthodox Western medicine. Despite a long history of use, many herbs have not been submitted to rigorous scientific testing and there are reports of hepatotoxicity. We describe a woman who developed acute hepatitis after drinking an herbal remedy containing Teucrium viscidum.

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.

A report of two families with sarcosinaemia in Hong Kong and revisiting the pathogenetic potential of hypersarcosinaemia.

Introduction: Sarcosinaemia is a rare metabolic disorder which has not been reported in Asia.

Clinical Picture: The urine samples of 2 patients were screened as a routine metabolic screening offered for patients with mental retardation in our hospital. We used gas chromatography-mass spectrometry (GC-MS) which is capable of detecting abnormal pattern in amino acids and organic acids.

Hidden aconite poisoning: identification of yunaconitine and related aconitum alkaloids in urine by liquid chromatography-tandem mass spectrometry.

Poisoning from aconite occurs worldwide as a result of misuse of the potent plant. Laboratory investigation into suspected intoxication cases is challenging because the content of toxic aconitum alkaloids varies depending on the plant source, market processing, dosing protocol, hydrolytic degradation, and metabolic transformation. Using a triple-quadrupole tandem mass spectrometer, a group screening method was developed based on the mass-fragmentographic scheme of common aconitum alkaloids.

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.

Detection of Herba Aristolochia Mollissemae in a patient with unexplained nephropathy.

The authors report a case of unexplained nephropathy 2 months after ingestion of Herba Aristolochia Mollissemae in a patient with long-standing Crohn's disease and recently diagnosed carcinoma of the colon. It presented as a relentlessly progressing hypocellular interstitial nephritis 5 months after cessation of an earlier course of mesalazine. The patient finally had end-stage renal failure 12 months after taking herbs and required hemodialysis.

Novel mutations of the AGXT gene causing primary hyperoxaluria type 1.

Background: Primary hyperoxaluria type 1 (PH1), an inherited cause of nephrolithiasis, is due to a functional defect of the liver-specific peroxisomal enzyme alanine:glyoxylate aminotransferase (AGT). A definitive PH1 diagnosis can be established by analyzing AGT activity in liver tissue or mutation analysis of the AGXT gene.

Methods: The molecular basis of PH1 in three Chinese patients, two with adult-onset and one with childhood-onset recurrent nephrolithiasis, was established by analyzing the entire AGXT gene.

DNA-based diagnosis of isolated sulfite oxidase deficiency by denaturing high-performance liquid chromatography.

Isolated sulfite oxidase deficiency is a rare autosomal recessive disease, characterized by severe neurological abnormalities, seizures, mental retardation, and dislocation of the ocular lenses, that often leads to death in infancy. There is a special demand for prenatal diagnosis, since no effective treatment is available for isolated sulfite oxidase deficiency. Until now, the cDNA sequence of the sulfite oxidase (SUOX) gene has been available, but the genomic sequence of the SUOX gene has not been published.