Haploidentical Transplant Achieves Long-Term Remission in Relapsed Refractory Leukemia With Fludarabine-Induced Neurotoxicity Complication.

Hematopoietic stem cell transplant is potentially curative for relapsed/refractory leukemia. However, neurotoxicity is common and has been reported in 11% to 59% of children following hematopoietic stem cell transplant. Most pediatric studies of the neurological effects of hematopoietic stem cell transplant have focused on acute neurotoxicity. Limited information is available for long-term neurotoxicity, particularly those cases that are severe and permanent and caused by conditioning chemotherapy. Here, we report 2 cases of relapsed acute lymphoblastic leukemia that achieved long-term remission by haploidentical hematopoietic stem cell transplant but remained complicated with severe and persistent fludarabine-induced neurotoxicity.

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.

Recurrent and novel mutations of GCDH gene in Chinese glutaric acidemia type I families.

Glutaric acidemia type I is caused by mutations of the glutaryl-CoA dehydrogenase (GCDH) gene resulting in loss of GCDH enzyme activity. Patients present with progressive dystonia and lesions in basal ganglia. Dietary treatment, when instituted from the early neonatal period, markedly reduces dystonia and morbidity. Early diagnosis and prenatal diagnosis will be facilitated by knowledge of locally prevalent GCDH mutations. Several common GCDH mutations have been found in different ethnic groups. GCDH mutations were studied in 5 Chinese glutaric acidemia type I families. We detected two novel recurrent mutations (A219T and IVS10-2A>C) which were found in two unrelated families. An asymptomatic carrier of IVS10-2A>C was also found on screening of 120 individuals. Other mutations were identified, including two other novel (R386G & IVS3+1G>A) and two known mutations (G178R & R355H). Fibroblasts from patients carrying the novel mutations were confirmed to be deficient for GCDH activity. This is the first report of GCDH mutations describing recurrent mutations in Chinese patients. The carrier rate of IVS10-2A>C may be particularly high in Chinese.

Pertussis--a re-emerging infection?

Seven cases of pertussis in patients aged between 1 and 6 months detected over 3 months were reported. Paroxysmal cough (six cases), post-tussive vomiting (three cases) and poor feeding (three cases) were the most common presenting symptoms. Bordetella pertussis was isolated from six patients. The total leucocyte counts were mildly increased (10.8-15.6x10(9)/L). The lymphocyte counts were markly raised (59-73%) and appear to be useful indicators of pertussis. It appears that herd immunity does not offer adequate protection to the vulnerable group even in well-vaccinated populations. High vaccination coverage should be maintained, and vaccination should be given as early an age as possible. Aggressive efforts to identify cases and contacts are essential. Health care workers should have a high index of suspicion for pertussis, in particular for those with paroxysmal cough and high lymphocyte counts so as to give timely diagnosis and treatment.

Unusual neurological presentation of neuroblastoma.

Acute cerebellar ataxia and opsomyoclonus are presenting signs of occult neuroblastoma for a substantial proportion of paediatric patients. Cerebellar ataxia may be due to antibodies against the neuroblastoma cross-reacting with cerebellar tissue. This report is of a 26-month-old boy who presented with encephalitis-like features of ataxia, seizures, decreased consciousness, and involuntary movements. Magnetic resonance imaging of the brain and spine were normal 2 weeks after presentation. The child did not have the classical signs of opsoclonus or myoclonus at any stage of the disease but was found to have occult neuroblastoma. The late demyelinating changes seen on magnetic resonance imaging of the brain support an immunological basis for the paraneoplastic manifestations of occult neuroblastoma in this child. Occult neuroblastoma should be considered as one of the differential diagnoses for children presenting with persisting encephalitis-like features in the presence of normal neuroimaging findings.

Dentatorubral-pallidoluysian atrophy in two Chinese families in Hong Kong.

We report on two Hong Kong Chinese families with dentatorubral-pallidoluysian atrophy. Two children in one family presented with progressive myoclonic epilepsy syndrome, and two children in the other family presented with ataxochoreo-athetoid symptoms. Early-onset childhood dentatorubral-pallidoluysian atrophy involved mental retardation, whereas myoclonic epilepsy was the predominant complaint in later-onset childhood version of the disease. Aspiration pneumonia was common in the late stage of disease. Dentatorubral-pallidoluysian atrophy is an autosomal dominant condition attributed to CAG trinucleotide repeats in the dentatorubral-pallidoluysian atrophy gene. The four children in this series had 63 to 79 CAG repeats. The expanded allele was inherited from the father in both families. One father had 54 CAG repeats and was asymptomatic; the other had 66 repeats and had an unsteady gait. Because the radiological, electroencephalographic, and electrophysiological findings were non-specific, we suggest that DRPLA gene testing should be performed in any child presenting with a variable combination of myoclonic epilepsy, mental retardation or developmental regression, and ataxochoreo-athetosis.

Inherited metabolic diseases in the Southern Chinese population: spectrum of diseases and estimated incidence from recurrent mutations.

Inherited metabolic diseases (IMDs) are a large group of rare genetic diseases. The spectrum and incidences of IMDs differ among populations, which has been well characterised in Caucasians but much less so in Chinese. In a setting of a University Hospital Metabolic Clinic in Hong Kong, over 100 patients with IMDs have been seen during a period of 13 years (from 1997 to 2010). The data were used to define the spectrum of diseases in the Southern Chinese population. Comparison with other populations revealed a unique spectrum of common IMDs. Furthermore, the incidence of the common IMDs was estimated by using population carrier frequencies of known recurrent mutations. Locally common diseases (their estimated incidence) include (1) glutaric aciduria type 1 (∼1/60,000), (2) multiple carboxylase deficiency (∼1/60,000), (3) primary carnitine deficiency (∼1/60,000), (4) carnitine-acylcarnitine translocase deficiency (∼1/60,000), (5) glutaric aciduria type 2 (∼1/22,500), (6) citrin deficiency (∼1/17,000), (7) tetrahydrobiopterin-deficient hyperphenylalaninaemia due to 6-pyruvoyl-tetrahydropterin synthase deficiency (∼1/60,000), (8) glycogen storage disease type 1 (∼1/150,000). In addition, ornithine carbamoyltransferase deficiency and X-linked adrenoleukodystrophy are common X-linked diseases. Findings of the disease spectrum and treatment outcome are summarised here which may be useful for clinical practice. In addition, data will also be useful for policy makers in planning of newborn screening programs and resource allocation.

A Chinese girl with Leigh syndrome: effect of botulinum toxin on dystonia.

Leigh syndrome is a form of neurodegenerative disease which is associated with intracranial infarcts. The diagnosis is made by finding hyperlactacidaemia together with cerebral infarcts on neuroimaging. We report a 4-year-old Chinese girl with Leigh syndrome who had several atypical features. She presented with generalized dystonia and developmental regression. In addition, she suffered from an unusual feature of bladder dystonia. This patient appeared to be suffering from respiratory chain complex I deficiency from studies on cultured skin fibroblasts. Assays for respiratory chain enzymes as well as mitochondrial DNA point mutations and major deletions in muscle were normal. Dystonia persisted despite treatments with muscle relaxants and a ketogenic diet. Intramuscular botulinum toxin resulted in significant relief of dystonia.

Red eyes as the initial presentation of systemic meningococcal infection.

The present paper is a report of a 14-month-old boy who presented with fever, coryzal symptoms and red eyes. The patient developed a generalized tonic clonic convulsion on day 2 of his illness. Ophthalmological assessment demonstrated bilateral hypopyon and vitreous opacity resulting from endophthalmitis. Cerebrospinal fluid was positive for Neisseria meningitidis (A, C, Y, W 135) by latex agglutination. He was treated with high dose intravenous cefotaxime and intravitreal ceftazidime. He made good recovery and his vision was preserved. In view of the potential morbidity and mortality associated with systemic meningococcal infection, the presence of red eye and hypopyon provides important diagnostic clues indicating the need to investigate beyond superficial conjunctivitis. It should prompt the clinician to recognize endopthalmitis early and accurately diagnose this serious disease.