Dystroglycanopathy with two novel POMT1 mutations in a Chinese boy with developmental delay and muscular dystrophy

Alpha-dystroglycanopathies are a group of diseases due to reduced glycosylation of alpha-dystroglycan, which commonly result from mutations in POMT1, POMT2, and POMGnT1. Patients with alpha-dystroglycanopathies present with muscular, cerebral, and ocular involvements with differing severities. We reported a boy who presented with muscular dystrophy, developmental delay, and non-specific white matter lesions. Mutation analysis of POMT1 was performed and revealed two novel mutations, a substitution mutation (c.176T>G) and a duplication mutation (c.2059dupC) which results in premature termination of translation. In-silico prediction in five different platforms concurred that the substitution is damaging, and functional studies by immunofluorescence revealed lack of staining in the carbohydrate moiety of alpha-dystroglycan, confirming the molecular findings in a functional manner. In conclusion, we reported the first case of genetically confirmed alpha-dystroglycanopathy due to mutations in POMT1 in Chinese.

Lathosterolosis: a disorder of cholesterol biosynthesis resembling smith-lemli-opitz syndrome

Lathosterolosis is an inborn error of cholesterol biosynthesis due to deficiency of the enzyme 3-beta-hydroxysteroid-delta-5-desaturase (or sterol-C5-desaturase or SC5D). This leads to a block in conversion of lathosterol into 7-dehydrocholesterol. Only three patients with lathosterolosis have been reported in literature, of which one survived. We report a patient with dysmorphism, multiple congenital anomalies, and developmental delay, initially suspected to have Smith-Lemli-Opitz syndrome, who was later found to have elevated levels of lathosterol in both plasma and fibroblasts. Genetic study confirmed a compound heterozygous mutation in the sterol-C5-desaturase-like (SC5DL) gene on chromosome 11q23. Simvastatin was started as a treatment therapy and it resulted in normalization of blood lathosterol level and improvement in the neurodevelopmental profile. However, additional patients are needed for better delineation of the clinical spectrum, genotype-phenotype correlation, and potential efficacy of simvastatin treatment in this rare disorder. If the presence of distinctive facial features and limb anomalies raise the suspicion of a cholesterol biosynthesis defect, testing of full sterol profile is warranted as normal cholesterol or 7-dehydrocholesterol levels cannot rule out the diagnosis of cholesterol synthesis defect like lathosterolosis.

Diagnosis of dihydropyrimidinase deficiency in a Chinese boy with dihydropyrimidinuria

Dihydropyrimidinase deficiency is an autosomal recessive inborn error of metabolism characterised by the presence of dihydropyrimidinuria. Its clinical presentation is variable and has also been reported in asymptomatic subjects. We report the first case of dihydropyrimidinase deficiency in Hong Kong, which is also the first reported in a Chinese subject. The patient was a 32-month-old boy who presented with language development delay. Biochemical analysis confirmed markedly increased urinary excretion of dihydrouracil and dihydrothymine, whilst DNA testing confirmed that the patient was compound heterozygous for two missense mutations, one known (p.R302Q) and the other was novel (p.N16K).

Arginase deficiency with new phenotype and a novel mutation: contemporary summary

In areas without expanded newborn screening, instead of presenting neonatally, patients with arginase deficiency typically present with spastic paraplegia in early childhood. Diagnosis of this rare neurometabolic disease poses the first challenge because it is often misdiagnosed as cerebral palsy during initial stages. We describe arginase deficiency in a 20-year-old woman with spastic paraplegia, progressive dystonia, dementia, peripheral neuropathy, epilepsy, liver cirrhosis, and non-B/non-C hepatocellular carcinoma. A novel homozygous mutation NM_000045.2 (ARG1):c.673del (p.Arg225GlyfsX5) was detected. We suggest that all children presenting with progressive neurodegeneration or spastic paraplegia in the absence of risk factors for cerebral palsy should be screened for inborn errors of metabolism, including arginase deficiency. For monitoring urea cycle defects, noninvasive imaging screening for liver fibrosis and hepatocellular carcinoma can help ensure early detection, with potential treatment implications.

In search of the diagnosis, and the patient: transient galactosemia demystified after 14 years

Infantile galactosemia can be caused by inborn errors of galactose metabolism or other rare causes like Fanconi-Bickel syndrome, congenital porto-systemic shunting and multiple hepatic arterio-venous malformations. All these disease entities are however not commonly seen. We report a case of transient infantile galactosemia who first presented in the 1990s, for which no underlying pathology could be identified despite extensive investigations. The diagnosis had not been apparent until after more than a decade, at that time the patient was lost to contact. Considering the potential diagnosis an important and significant one, efforts were made by the case pathologists and clinicians to search for the patient. Ethical dilemmas were encountered during the search of the patient, which involved issues of patient confidentiality and autonomy, and the doctors' duty-to-care. Modern biochemical and molecular testing confirmed the diagnosis after the patient was finally found. The case illustrates the power of molecular testing to retrospectively diagnose an inherited metabolic disease when biochemical abnormalities have subsided, the value of an accurate and precise diagnosis, and the importance of appropriate genetic counselling in an apparently asymptomatic patient in the era of personalized medicine.

Genetic diagnosis of severe myoclonic epilepsy of infancy (Dravet syndrome) with SCN1A mutations in the Hong Kong Chinese patients

Epilepsy is a clinically and genetically heterogeneous group of disorders. The advent of molecular genetics brings unprecedented advancement in diagnostic molecular pathology and reduces over-reliance on traditional clinical classification. Severe myoclonic epilepsy of infancy or Dravet syndrome is a catastrophic infantile-onset epilepsy. We report two unrelated Hong Kong Chinese patients with this condition presenting with febrile seizures, epilepsy with different semiologies, psychomotor retardation, and recurrent status epilepticus. Two different mutations were characterised, viz NM_001165963.1: c.680T>G; NP_001159435.1: p.I227S and NM_001165963.1: c.3953T>G; NP_001159435.1: p.L1318R (novel). Genetic characterisation conveys a definitive diagnosis and is important from the perspective of selecting anti-epileptic drug therapy and genetic counselling.

Dark matter results from 100 live days of XENON100 data

We present results from the direct search for dark matter with the XENON100 detector, installed underground at the Laboratori Nazionali del Gran Sasso of INFN, Italy. XENON100 is a two-phase time-projection chamber with a 62 kg liquid xenon target. Interaction vertex reconstruction in three dimensions with millimeter precision allows the selection of only the innermost 48 kg as the ultralow background fiducial target. In 100.9 live days of data, acquired between January and June 2010, no evidence for dark matter is found. Three candidate events were observed in the signal region with an expected background of (1.8 ± 0.6) events. This leads to the most stringent limit on dark matter interactions today, excluding spin-independent elastic weakly interacting massive particle (WIMP) nucleon scattering cross sections above 7.0 × 10(-45) cm(2) for a WIMP mass of 50 GeV/c(2) at 90% confidence level.

Persistent hypocalcaemia in a Chinese girl due to a novel de-novo activating mutation of the calcium-sensing receptor gene

A significant proportion of patients formerly diagnosed with idiopathic hypoparathyroidism actually have activating mutation of the calcium-sensing receptor (CaSR) gene. Awareness of the possibility of activating mutation of CaSR gene in patients with sporadic idiopathic hypoparathyroidism is important because of its relevance to clinical management. This report is of a novel activating mutation of the CaSR gene identified in a 10-year-old Chinese girl who was initially diagnosed as having idiopathic hypoparathyroidism at 6 years of age after presenting with seizures. Her serum calcium level was difficult to maintain near the lower limit of normal despite treatment with high-dose calcitriol. Treatment with calcitriol produced significantly elevated urinary calcium-to-creatinine ratio. Direct sequencing of the CaSR gene showed a novel heterozygous mutation (p.Q735P (c.2204A>C)). Molecular genetic analysis of her parents demonstrated that both parents did not harbour the child's mutation, indicating that her mutation had arisen de novo.

Heterogeneous mutations of the ATP2C1 gene causing Hailey-Hailey disease in Hong Kong Chinese

BACKGROUND

Hailey-Hailey disease (HHD) is a rare autosomal dominant dermatosis. It causes suprabasilar acantholysis leading to vesicular and crusted erosions affecting the flexures. Mutation of ATP2C1 gene encoding the human secretory pathway Ca(2+) /Mn(2+) -ATPase (hSPCA1) was identified to be the cause of this entity.

OBJECTIVE

The aim of this study was to study the mutational profile of the ATP2C1 gene in Hong Kong Chinese patients with HHD.

METHODS

Patients with the clinical diagnosis of HHD proven by skin biopsy were included in this study. Mutation analysis was performed in 17 Hong Kong Chinese patients with HHD.

RESULTS

Ten mutations in the ATP2C1 gene were found. Six of these were novel mutations. The novel mutations included a donor splice site mutation (IVS22+1G>A); a missense mutation (c.1049A>T); two deletion mutations (c.185_188delAGTT and c.923_925delAAG); an acceptor splice site mutation (IVS21-1G>C) and an insertion mutation (c.2454dupT).

CONCLUSION

The six novel mutations provide additions to the HHD mutation database. No hot-spot mutation was found and high allelic heterogeneity was demonstrated in the Hong Kong Chinese patients.

First dark matter results from the XENON100 experiment

The XENON100 experiment, in operation at the Laboratori Nazionali del Gran Sasso in Italy, is designed to search for dark matter weakly interacting massive particles (WIMPs) scattering off 62 kg of liquid xenon in an ultralow background dual-phase time projection chamber. In this Letter, we present first dark matter results from the analysis of 11.17 live days of nonblind data, acquired in October and November 2009. In the selected fiducial target of 40 kg, and within the predefined signal region, we observe no events and hence exclude spin-independent WIMP-nucleon elastic scattering cross sections above 3.4 × 10⁻⁴⁴  cm² for 55  GeV/c² WIMPs at 90% confidence level. Below 20  GeV/c², this result constrains the interpretation of the CoGeNT and DAMA signals as being due to spin-independent, elastic, light mass WIMP interactions.

Diagnosis of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes in a Chinese family by PCR/restriction enzyme analysis

The clinical presentation and the biochemical and molecular genetic findings are described in a 13 year old Chinese boy with MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes). The diagnosis was initially suspected because of the characteristic clinical features and the strong family history of convulsions. Using polymerase chain reaction-restriction enzyme analysis, the heteroplasmic nt3243 A-->G mutation in mtDNA of peripheral blood leucocytes and a muscle sample was demonstrated. The oligosymptomatic relatives were then screened by this method and the degree of heteroplasmy was analysed. This appears to be the first report of a MELAS family in Hong Kong with this described mutation. Molecular genetic techniques are advantageous in the diagnosis of MELAS.

A novel duplication at the putative DNA polymerase alpha arrest site and a founder mutation in Chinese in the IVD gene underlie isovaleric acidaemia

Isovaleric acidaemia is a rare inherited organic acidaemia associated with a characteristic odour in affected patients. Fewer than 40 causative mutations have been reported to date. We report a case in a Hong Kong Chinese neonate who presented with respiratory distress and acute encephalopathy requiring aggressive resuscitation and treatment. Residual gross motor developmental delay was still observed at the age of 16 months. The child was subsequently found to harbour a known missense mutation (c.A1199G [p.Y371C]) and a novel 4-bp duplication (c.1148_1151dupGCTA [p.Y355X]) in the IVD gene. We suggest that the former is a founder mutation in the Chinese population and propose an explanation for the duplication event. Strategies that may achieve early diagnosis and prompt treatment include raising awareness of this condition, implementation of a tandem mass spectrometry neonatal screening programme, and local acquisition of appropriate medications for these metabolic diseases.

Biochemical and molecular characterization of tyrosine hydroxylase deficiency in Hong Kong Chinese

Tyrosine hydroxylase deficiency is a rare neurotransmitter disorder affecting the rate-limiting step in catecholamine biosynthesis. There are about 40 cases reported worldwide. Here, we report the biochemical and molecular findings of eight unrelated Chinese patients with tyrosine hydroxylase deficiency. We have identified eight novel mutations with 5 missense, 2 nonsense and 1 splicing mutations in the TH gene, namely p.R153X, p.R169X, p.G294R, p.G315S, p.A385V, p.I394T, p.G408R, and c.1163+5G>C. The mutations of the TH gene in Chinese are heterogeneous.

Hereditary spastic paraplegia: identification of an SPG3A gene mutation in a Chinese family

Hereditary spastic paraplegias are a heterogeneous group of chronic central motor system disorders, characterised by progressive lower limb spasticity. Hereditary spastic paraplegia is clinically classified into pure and complicated forms, by the absence or presence of additional neurological or extra-neurological features. Hereditary spastic paraplegias follow all modes of inheritance and the pure-form autosomal dominant type is the one most commonly reported. Spastic paraplegia 4, autosomal dominant (SPG4, MIM#182601) and spastic paraplegia 3, autosomal dominant (SPG3A, MIM#182600), account for most autosomal dominant hereditary spastic paraplegias. Using DNA mutation analysis, the authors identified an SPG3A missense mutation (p.R239C) in a Chinese family where three members have early-onset pure spastic paraplegia. To our knowledge, this is the first report of a gene mutation in hereditary spastic paraplegias in our locality. DNA-based diagnosis plays a key role in the early diagnosis of familial hereditary spastic paraplegias.

Effects of glycemic index meal and CHO-electrolyte drink on cytokine response and run performance in endurance athletes

OBJECTIVE

To examine the effect of the glycemic index (GI) of a pre-exercise (PRE-ex) meal on plasma cytokine responses and endurance performance when carbohydrate-electrolyte (CHO-E) drink was consumed during exercise.

METHODS

Eight endurance-trained male runners (age: 28.6+/-2.7 years; body mass: 61.9+/-1.71 kg; V O(2max): 58.5+/-1.6 ml kg(-1)min(-1)) completed three trials in a randomized order. The pre-exercise meal consisted of either high-GI (HGI) (GI=83), low-GI (LGI) foods (GI=36) or control (CON) (low energy sugar-free jelly) was given to the participant 2h before a 21-km performance run on a level treadmill. During each trial, 2 ml kg(-1) BM of 6.6% CHO-E solution was consumed immediately before exercise and every 2.5-km afterward. Blood samples were collected before (pre-meal), and 120 min after ingestion the meal (120 min), immediately (POST), and 60 min (POST-60 min) after exercise.

RESULTS

No difference was found in time to complete the 21-km run between LGI and HGI. The interleukin-6 (IL-6) level increased by more than 100 times immediately after exercise in the three trials and returned to the basal level only on LGI at POST-60 min. In contrast, interleukin-2 (IL-2) level showed a transitory decrease at POST on CON (p<0.001). Glucose concentrations did not recover to the pre-meal level by POST-60 min on HGI only. Cortisol concentrations increased throughout the exercise and were lower on LGI when compared with CON (p<0.05) at POST-60 min.

CONCLUSIONS

HGI and LGI demonstrated similar performance when CHO-E solution was consumed during a 21-km run. However, pre-exercise LGI meal attenuated the increases in cortisol and quickened the recovery of the increased IL-6 value.

A novel CASR gene mutation in an octogenarian with asymptomatic hypercalcaemia

An increasing number of patients are diagnosed with primary hyperparathyroidism after having hypercalcaemia detected incidentally during routine biochemical screening. Many are asymptomatic at the time of diagnosis. An 80-year-old woman was found to have asymptomatic hypercalcaemia. Initial investigations suggested a diagnosis of primary hyperparathyroidism. Subsequent investigations revealed that, in fact, she had familial hypocalciuric hypercalcaemia. Direct DNA sequencing of the calcium-sensing receptor (CASR) gene confirmed that the patient was heterozygous for c.2501delC, a novel frame shift mutation predicted to cause loss of function of the CASR gene. Several other family members were subsequently found to carry the same mutation. Suspected cases of hypocalciuric hypercalcaemia should be confirmed by detection of mutations within the CASR gene. Establishing the correct diagnosis will enable the patient and family members to avoid unnecessary investigations or operations.

Pantothenate kinase-associated neurodegeneration in two Chinese children: identification of a novel PANK2 gene mutation

Pantothenate kinase-associated neurodegeneration (formerly Hallervorden-Spatz syndrome), the most prevalent form of neurodegeneration with brain iron accumulation, is a rare degenerative brain disease characterised by predominantly extrapyramidal dysfunction resulting from mutations in the PANK2 (pantothenate kinase 2) gene. Using DNA mutation analysis, the authors identified a novel missense mutation (P354L) in exon 4 of the PANK2 gene in an adolescent with classic pantothenate kinase-associated neurodegeneration. DNA-based diagnosis of pantothenate kinase-associated neurodegeneration plays a key role in determination, and can make the diagnosis more simply, directly, and economically because it obviates the need for unnecessary biochemical tests. Once pantothenate kinase-associated neurodegeneration-like symptoms are identified, mutation analysis and target screening for the family of the proband can provide efficient and accurate evidence of pantothenate kinase-associated neurodegeneration inheritance.

Determinants of chronic obstructive pulmonary disease in Chinese patients in Hong Kong

BACKGROUND

The prevalence of chronic obstructive pulmonary disease (COPD) is rising in many parts of the world. This is a study of risk factors for COPD in Chinese patients in Hong Kong.

DESIGN

Case-control study matched by sex and age (+/-5 years).

METHODS

A total of 289 consecutive patients with COPD were recruited from out-patient clinics while healthy controls were recruited from two sources: random population and community centres for senior citizens. All patients and controls underwent a questionnaire-based interview and spirometry.

RESULTS

The mean ages of COPD patients and controls were 71.1 +/- 9.4 and 67.5 +/- 9.3 years, respectively. The male to female ratio of COPD patients was 5 to 1. Smoking was found to be the most important determinant for COPD, followed by poor education and low body mass index adjusted for confounders. A dose-dependent relationship was found between the risk of COPD and pack-years smoked. Place of birth, exposure to environmental tobacco smoke and a history of asthma and tuberculosis were not associated with increased risk of COPD.

CONCLUSION

Despite a progressive reduction in prevalence, smoking remains the most important predictor of COPD in Hong Kong. Greater anti-smoking efforts are warranted.

A Chinese family with familial paraganglioma syndrome due to succinate dehydrogenase deficiency

We report the genetic characteristics of a family with familial paraganglioma syndrome. The index patient was diagnosed with carcinoid tumour of the bronchus at the age of 30 years then later diagnosed with bilateral phaeochromocytoma. His sister had bilateral carotid body tumours. Mutational analyses of succinate dehydrogenase B and SDHD on the index patient showed him to be heterozygous for the M1I mutation of the SDHD gene. A genetic analysis revealed that his sister also had succinate dehydrogenase deficiency with the same mutation. Pre-symptomatic testing confirmed the genetic diagnosis, and led to a clinical diagnosis in an otherwise asymptomatic sibling. Comparison with other known cases of M1I mutation suggests that this is a founder mutation in the Chinese population. Genetic analysis of the succinate dehydrogenase genes can provide a specific diagnosis and allow for genetic screening of at-risk individuals.

Carnitine-acylcarnitine translocase deficiency in three neonates presenting with rapid deterioration and cardiac arrest

We report on three Chinese neonates with carnitine-acylcarnitine translocase deficiency. They presented within the first 48 hours of life. Two neonates were found in cardiac arrest; one of them survived after resuscitation. The third neonate suddenly developed cardiorespiratory insufficiency and succumbed eventually. The clustering of three cases in 5 years suggests that carnitine-acylcarnitine translocase deficiency is not rare in our Chinese population. We advocate that investigation for metabolic diseases including carnitine-acylcarnitine translocase deficiency should be performed in cases of sudden infant death and unexplained abrupt clinical deterioration in the early neonatal period. Non-ketotic hypoglycaemia is an early clue. The mainstay of initial treatment is glucose infusion at a rate greater than 7 mg/kg/minute, which inhibits beta-oxidation of fatty acids (the defective enzymatic steps in carnitine-acylcarnitine translocase deficiency) and thus prevents the accumulation of toxic long-chain acylcarnitines.