Diagnostic yield of array CGH in patients with autism spectrum disorder in Hong Kong.

BACKGROUND: Chromosomal microarray offers superior sensitivity for identification of submicroscopic copy number variants (CNV) and it is advocated to be the first tier genetic testing for patients with autism spectrum disorder (ASD). In this regard, diagnostic yield of array comparative genomic hybridization (CGH) for ASD patients is determined in a cohort of Chinese patients in Hong Kong. METHODS: A combined adult and paediatric cohort of 68 Chinese ASD patients (41 patients in adult group and 27 patients in paediatric group). The genomic DNA extracted from blood samples were analysed by array CGH using NimbleGen CGX-135K oligonucleotide array. RESULTS: We identified 15 CNV and eight of them were clinically significant. The overall diagnostic yield was 11.8 %. Five clinically significant CNV were detected in the adult group and three were in the paediatric group, providing diagnostic yields of 12.2 and 11.1 % respectively. The most frequently detected CNV was 16p13.11 duplications which were present in 4 patients (5.9 % of the cohort). CONCLUSIONS: In this study, a satisfactory diagnostic yield of array CGH was demonstrated in a Chinese ASD patient cohort which supported the clinical usefulness of array CGH as the first line testing of ASD in Hong Kong.

NMR-based urinalysis for rapid diagnosis of ß-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. In severe cases, patients may present with profound neurological deficit including hypotonia, seizures and mental retardation. Using NMR-based urinalysis, this condition can be rapidly diagnosed within 15 min. CASE: An 11-month-old Chinese boy had dual molecular diagnoses, ß-ureidopropionase deficiency and Dravet syndrome. He presented with intractable and recurrent convulsions, global developmental delay and microcephaly. Urine organic acid analysis using GC-MS and NMR-based urinalysis showed excessive amount of ß-ureidopropionic acid and ß-ureidoisobutyric acid, the two disease-specific markers for ß-ureidopropionase deficiency. Genetic analysis confirmed homozygous known disease-causing mutation UPB1 NM_016327.2: c.977G>A; NP_057411.1:p.R326Q. In addition, genetic analysis for Dravet syndrome showed the presence of heterozygous disease-causing mutation SCN1A NM_001165963.1:c.4494delC; NP_001159435.1:p.F1499Lfs*2. CONCLUSIONS: The differentiation between Dravet syndrome and ß-ureidopropionase deficiency is clinically challenging since both conditions share overlapping clinical features. The detection of urine ß-ureidoisobutyric and ß-ureidopropionic acids using NMR or GC-MS is helpful in laboratory diagnosis of ß-ureidopropionase deficiency. The disease-causing mutation, c.977G>A of ß-ureidopropionase deficiency, is highly prevalent in Chinese population (allele frequency=1.7%); ß-ureidopropionase deficiency screening test should be performed for any patients with unexplained neurological deficit, developmental delay or autism.

Increasing the recipient benefit/donor risk ratio by lowering the graft size requirement for living donor liver transplantation.

In living donor liver transplantation (LDLT), a right liver graft is larger than a left liver graft and hence leads to better recipient survival. However, in comparison with donor left hepatectomy, donor right hepatectomy carries a higher donor risk. We estimated the expansion of the applicability of left liver living donor liver transplantation (LLDLT) by lowering the graft weight (GW)/standard liver volume (SLV) ratio in increments of 5%. Consecutive LDLT cases were included in this study. The results of computed tomography volumetry provided the graft volume measurements, and the GW was derived from the graft volume with the conversion factor of 1.19 mL/g. We tried to estimate how many more times LLDLT would have been feasible if the GW/SLV requirement had been lowered to 40%, 35%, 30%, or 25%. In all, 361 consecutive donor-recipient pairs underwent LDLT. Right liver living donor liver transplantation (RLDLT) accounted for 95% of the LDLT cases. Most recipients were male (74.2%), and most donors were female (60.4%). The median GW/SLV ratio was 46% (47% for RLDLT and 37% for LLDLT, P < 0.001). Two of the 218 female donors donated the left liver, and 12 of the 93 female recipients received a left liver. In 147 of the 173 cases (85%) when the donor was female and the recipient was male, the GW/SLV ratio did not reach 30%. LLDLT could have been performed more often than 5% of the time if a lower GW/SLV requirement had been adopted. With GW/SLV ratios ≥ 40%, ≥ 35%, ≥ 30%, and ≥ 25%, the proportion of LLDLT cases would have risen from 5% to 5.8%, 12.5%, 29.1%, and 62.3%, respectively. LLDLT could have been performed approximately twice as often with every 5% reduction of the GW/SLV requirement. In conclusion, lowering the graft size requirement could improve the applicability of LLDLT and hence reduce donor risk.

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. METHODS: Urine metabolic profiles performed by gas chromatography-mass spectrometry (GC-MS) in a 31-month period were retrospectively reviewed: those with vanilmandelic acid concentration lower than one percentile plus the presence of 3-o-methyldopa were defined as positive and the patients were further evaluated. RESULTS: Among 1046 metabolic profiles (from 845 patients) reviewed, 3 profiles from 2 patients were screened positive: both cases had compatible CSF neurotransmitter profiles and the diagnosis was further confirmed by genetic analysis of DDC gene. 13 negative urinary metabolic profiles from 7 patients who had CSF neurotransmitters analyzed were identified as controls: all 7 CSF neurotransmitter profiles were not compatible for AADC deficiency. CONCLUSIONS: The GC-MS-based urine metabolic profiling was shown to be a satisfactory screening tool for AADC deficiency. Further confirmation can be performed by mutation analysis in the DDC gene, thus avoiding risks of lumbar puncture. We advocate all ethnic Chinese patients presenting with dystonia have their urine organic acids analyzed before proceeding to CSF neurotransmitters analysis.

Conservation of the axilla: an audit of sentinel lymph node biopsy after a new start.

BACKGROUND: Four hundred twenty-eight patients with a diagnosis of breast cancer were assessed. All patients underwent axillary ultrasonographic scanning preoperatively or at the time of initial breast imaging. Suspicious axillary glands underwent core needle biopsy under ultrasonographic guidance. PATIENTS AND METHODS: The majority of patients were in the age range of 40 to 80 years. Sentinel lymph node biopsy (SLNB) was performed in 360 patients. RESULTS: Sixty-eight patients had axillary clearance as a first axillary procedure. Of these patients, 55 had a preoperative diagnosis of a positive axillary gland in the axilla on ultrasonographically guided core needle biopsy, and 13 had clinically palpable axillary lymph glands. Seventy-one patients (21%) had a positive sentinel lymph node on histopathologic examination after hematoxylin and eosin (H & E) staining. Preoperative scans of the axilla had been reported as normal in these patients. In 68 patients, further axillary surgery was performed to clear the axilla; 24 of these patients (35%) had more positive glands in the axilla. In 44 patients (65%) the sentinel lymph glands were the only positive glands. Of 224 patients with a tumor size ≤ 20 mm, there were 30 patients (14%) who had a positive sentinel node. Of 136 patients with a tumor size > 20 mm, there were 41 patients (33%) with positive sentinel nodes. CONCLUSIONS: Sentinel lymph node biopsy in breast cancer allowed conservation of the axilla in 80% (289/360) of patients with negative sentinel lymph nodes in this study. Preoperative ultrasonographically guided core needle biopsy reduced the need for a second operation in 55 patients (13%).

Evaluation of sleep disturbances in children with epilepsy: a questionnaire-based case-control study.

Epilepsy is a chronic neurological disorder accompanied by a wide range of comorbid conditions that can adversely affect the quality of life of children. Sleep disturbances not only predispose children to mood, cognitive, and behavioral impairments, but also have a significant impact on physical health. The aim of this study was to evaluate sleep patterns among Chinese children with epilepsy and healthy subjects in Hong Kong, and examine the relationship between parent-reported sleep problems and specific epilepsy parameters. We conducted a cross-sectional, questionnaire-based, case-control study and included 63 children with epilepsy and 169 healthy children aged between 4 and 12 years. The Children's Sleep Habits Questionnaire (CSHQ) was used as an assessment tool. Our results indicated that children with epilepsy have similar sleep patterns but greater sleep disturbances compared with healthy subjects. Sleep problems should not be overlooked, and a comprehensive review of the sleep habits of this group of patients should be conducted.

Expanding phenotype and clinical analysis of tyrosine hydroxylase deficiency.

This study included 12 Chinese patients with a wide spectrum of phenotypes of tyrosine hydroxylase deficiency. Seven females and 5 males, aged 2.2 to 41 years, had phenotypes ranging from severe type with onset at infancy to mild type with onset after 3 years of age. Patients with the severe type had encephalopathy with poor treatment response or infantile parkinsonism with motor delay. Patients with the less common mild type had dopa-responsive dystonia or a newly recognized predominant symptom of myopathy. Female siblings had more severe phenotypes. The phenotype and treatment outcomes were strongly related to a homovanillic acid level and homovanillic acid/5-hydroxyindolacetic acid ratio of less than 1 in the cerebrospinal fluid. Hyperprolactinemia was found in 50% of the severe cases. Levodopa was the mainstay of treatment, and early addition of selegiline resulted in a remarkable response in some patients. Treatment response for mild-type patients is universally good even with a treatment delay of 10 years after onset of neurological symptoms.

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. We here described a Chinese adolescent boy who enjoyed good health earlier and presented at the age of 14 years with severe vomiting. His condition deteriorated rapidly and he succumbed shortly after. With a travel history before presentation and the late age of onset, diagnosis was particularly difficult. Findings in perimortem biochemical investigations and postmortem autopsy were guiding but not diagnostic. The diagnosis of glutaric aciduria type II was finally confirmed by mutation analysis performed by direct sequencing on genomic DNA from peripheral blood, which identified 2 different unreported missense mutations, c.502G>T (p.V168F) and c.786A>G (p.Q262R), in ETFA. The father and the mother were found to be heterozygous for the 2 mutations in ETFA respectively. Subsequent molecular family screening also ruled out the disease in his elder sister, who had a history of convulsion and a suspicious plasma acylcarnitine profile, and freed her from life-long supplementation. The case showed that molecular autopsies should be part of routine postmortem examination of unexplained sudden death in all age groups and DNA-friendly samples should be routinely collected and archived. In the era of personalized medicine with the power of modern genetics, molecular diagnosis should be obtained for heterogeneous diseases with different genetic defects but sharing similar clinical and/or biochemical phenotypes.

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. Plasma sarcosine level was further quantified by GC-MS. The same methods were used in the investigations of asymptomatic family members. Urine examination by GC-MS revealed excessive amount of sarcosine in urine (normally undetectable) and their plasma sarcosine levels were raised. The 2 differential diagnoses of presence of sarcosine in urine--glutaric aciduria type II and folate deficiency--were ruled out by the absence of abnormal organic acids in the initial urine screen and by normal serum folate level respectively. Screening of the 2 families identified excessive sarcosine in urine in 2 siblings, one from each family. However, these 2 siblings of indexed patients thus identified have no neurological or developmental problem. CONCLUSION: Our finding was consistent with the notion that sarcosinaemia is a benign condition picked up coincidentally during screening for mental retardation.

Subacute sclerosing panencephalitis in children: prevalence in South China.

This investigation reports the prevalence and clinical profile of subacute sclerosing panencephalitis in two developed cities of southern China. A territory-wide survey was conducted to identify all subacute sclerosing panencephalitis cases diagnosed during 1988-2002 in Hong Kong and Macau. Altogether, 10 cases (male:female = 7:3) were identified of whom six were still alive. The prevalence rate of subacute sclerosing panencephalitis in Hong Kong and Macau in 2002 was 1 per million total population or 5.5 per million children. The mean age of presentation was 9.4 years (range = 4-14 years). Presenting features included myoclonus (60%), deterioration in school performance (30%), and transient visual impairment (10%). The clinical course was highly variable. Most had subacute course, but two deteriorated rapidly and died within 6 months. Seven children had measles infection, and the majority of infection (86%) occurred during the world measles epidemic in 1988. The mean interval between measles infection and onset of subacute sclerosing panencephalitis was 6.5 years (range = 3-11 years). There has been an increasing trend of subacute sclerosing panencephalitis in southern China after the measles outbreak in 1988. Active surveillance of subacute sclerosing panencephalitis for those with measles infection during the 1988 outbreak is necessary to conduct multicenter drug trials for this devastating disease.

Cervical myelopathy in an adolescent with Hallervorden-Spatz disease.

Hallervorden-Spatz disease is a rare neurodegenerative disorder characterized by progressive dystonia, rigidity, and dementia. In these patients, chronic repeated dystonic movements, especially of the head and neck, can lead to excessive stress on the cervical spine, resulting in early degenerative changes and myelopathy. This report focuses on a young patient with Hallervorden-Spatz disease who presented with C4 to C5 cervical disk extrusion and cord compression because of premature spondylotic changes of the cervical spine. Other authors have documented cervical spondylosis caused by movement disorders, but there had been no reported cases of cervical myelopathy as a complication of Hallervorden-Spatz disease. Because these patients already manifest a longstanding and progressive neurologic disorder, clinicians may encounter difficulties recognizing the symptoms and signs of new cervical pathology, especially if the spondylosis and myelopathy has an insidious onset. For follow-up of patients with Hallervorden-Spatz disease who have multiple disabilities, a multidisciplinary approach with active involvement of physiotherapists, occupational and speech therapists, experienced nurses, caregivers, and clinicians is recommended. The clinician should also monitor the neurologic and functional status of the patient and screen for cervical pathology if suspicion arises. Good control of dystonia may be helpful in prevention of cervical spondylosis but may be difficult to achieve. Treatment modalities for dystonia are also discussed.

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. In this study, we have performed a DNA-based diagnosis of isolated sulfite oxidase deficiency in a Chinese patient. To do so, we designed oligonucleotide primers for amplification of the predicted exons and intron-exon boundaries of the SUOX gene obtained from the completed draft version of the human genome. Using overlapping PCR products, we confirmed the flanking intronic sequences of the coding exons and that the entire 466-residue mature peptide is encoded by the last exon of the gene. We then performed mutation detection using denaturing high-performance liquid chromatography (DHPLC). The DHPLC chromatogram of exon 2b showed the presence of heteroduplex peaks only after mixing of the mutant DNA with the wild-type DNA, indicating the presence of a homozygous mutation. Direct DNA sequencing showed a homozygous base substitution at codon 160, changing the codon from CGG to CAG, which changes the amino acid from arginine to glutamine, i.e., R160Q. The DNA-based diagnosis of isolated sulfite oxidase deficiency will enable us to make an accurate determination of carrier status and to perform prenatal diagnosis of this disease. The availability of the genomic sequences of human genes from the completed draft human genome sequence will simplify the development of molecular genetic diagnoses of human diseases from peripheral blood DNA.