BackgroundDuring 2009/10 a major measles epidemic caused by genotype B3 occurred in South Africa. Measles inclusion body encephalitis (MIBE) was diagnosed in a number of highly immuno-compromised HIV patients. The diagnosis was based on typical clinical and MRI findings and positive measles virus PCR in brain or CSF.To characterize the brain virus, nucleoprotein, matrix, fusion and haemagglutinin genes from 4 cases was compared with virus from acutely infected patients.MethodscDNA was synthesized using random primers and viral genes were amplified by nested RT-PCR. PCR products were sequenced in the forward and reverse direction and a contig of each gene was created. Sequences were aligned with reference sequences from GenBank and other local sequences.ResultsBrain virus was very similar to the South African epidemic virus. Features characteristic of persistent measles virus in the brain were absent. Mutation frequency in brain virus was similar to epidemic virus and had the same substitution preference (U to C and C to U). The virus of 2 patients had the same L454W mutation in the fusion protein.ConclusionThe brain virus was very similar to the epidemic strain. The relatively few mutations probably reflect the short time from infection to brain disease in these highly immuno-compromised patients.

Episodic ataxias (EAs) are rare neurological channelopathies that are characterized by spells of imbalance and a lack of co-ordination. There are seven clinically recognized EAs and multiple isolated cases. Five disease-causing genes have been identified to date. We describe a novel form of autosomal dominant EA in a large three-generation Irish family. This form of EA presents in early childhood with periods of unsteadiness generalized weakness and slurred speech during an attack, which may be triggered by physical tiredness or stress. Linkage analysis undertaken in 13 related individuals identified a single disease locus (1p36.13-p34.3) with a LOD score of 3.29. Exome sequencing was performed. Following data analysis, which included presence/absence within the linkage peak, two candidate variants were identified. These are located in the HSPG2 and UBR4 genes. UBR4 is an ubiquitin ligase protein that is known to interact with calmodulin, a Ca 2 þ protein, in the cytoplasm. It also co-localizes with ITPR1 a calcium release channel that is a major determinant of mammal co-ordination. Although UBR4 is not an ion channel gene, the potential for disrupted Ca 2 þ control within neuronal cells highlights its potential for a role in this form of EA.

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Background The late-onset efavirenz neurotoxicity syndrome (LENS) presents as ataxia and/or encephalopathy with supratherapeutic efavirenz plasma concentrations (>4 µg/mL). Efavirenz is primarily metabolized by cytochrome P450 2B6 (CYP2B6), with CYP2A6 as an accessory pathway. We hypothesized that participants with LENS would predominantly be CYP2B6 slow metabolizers. The aim of our study was to determine the frequency of CYP2B6 slow metabolizers in participants with LENS. Methods Adult HIV-positive participants on efavirenz-based antiretroviral therapy presenting with LENS were prospectively enrolled. Genetic polymorphisms known to be associated with increased efavirenz plasma concentrations in CYP2B6 (rs3745274, rs28399499, rs4803419) and CYP2A6 (rs28399433) were selected and used to determine proportions of slow metabolizers. Pharmacokinetic analyses were performed using liquid chromatography–tandem mass spectrometry. Median (IQR) plasma efavirenz and 8-hydroxyefavirenz were described. Results Fifteen participants were enrolled. Thirteen (13/15) were Black-African and 13 were female. Median weight was 49.9kg with a median duration on efavirenz of 2.2 years. All 15 participants were successfully genotyped as slow CYP2B6 metabolizers, with 6 participants additionally having CYP2A6 heterozygous genotype. Thirteen were receiving the CYP2A6 enzyme inhibitor isoniazid, and all 15 were genotypic NAT2 slow or intermediate acetylators. Efavirenz plasma concentration was markedly increased at 50.5 (47.0–65.4) µg/mL; 8-hydroxyefavirenz concentration was markedly decreased at 0.10 (0.07–0.15) µg/mL. Conclusions Our cohort provides definitive evidence that LENS is associated with the CYP2B6 slow metabolizer genotype, with a median efavirenz plasma concentration >12-fold higher than the defined upper limit of the therapeutic range. Isoniazid and low body weight are important contributors to LENS development.

Acute intermittent porphyria (AIP), the most common porphyria affecting the nervous system, typically presents with neurovisceral crises followed by a motor neuropathy. We describe an unusual presentation in a young man with molecularly confirmed AIP. Case presentationA 23-year-old university student was referred to Groote Schuur Hospital, Cape Town, South Africa, with suspected motor neuron disease. Over the preceding year he had noticed insidious progressive weakness of both upper limbs. Initially, the weakness affected grip strength bilaterally, but within 9 months progressed to also involve proximal arm function. Ten months after onset, he developed profound leg weakness over a period of days, rendering him unable to walk without support. He had no bowel or bladder sphincter involvement and no bulbar symptoms, but complained of a weak cough. He had not experienced any neuropsychiatric symptoms or abdominal pain.Examination showed a thin and wasted man with marked amyotrophy involving all four limbs, both proximally and distally (Fig. 1). He was bed-bound, and unable to turn in bed, feed or dress himself. He had mild symmetrical facial weakness and a weak cough with a reduced vital capacity (<80% of expected). He had truncal weakness and a flaccid quadriparesis, but no fasciculations were noted: upper limb strength Medical Research Council (MRC) grade 1/5 proximal, 2/5 distal; lower limb strength 2/5 proximal, 3/5 distal. He was areflexic in the legs with either hyporeflexia (biceps and supinator reflexes) or areflexia (triceps reflexes) in the arms. Findings on sensory examination were normal apart from a patch of reduced sensibility for pinprick and touch over the left anteromedial thigh region. CLINICAL Corresponding author: C H Albertyn (christine.albertyn@uct.ac.za)Acute intermittent porphyria, the most common porphyria affecting the nervous system, typically presents with neurovisceral crises followed by a motor neuropathy. We describe a 23-year-old black South African man presenting with a progressive stuttering, lower motor neuron syndrome developing over months. He had not experienced pain or neuropsychiatric symptoms. One year after symptom onset he was bed-bound with a flaccid quadriparesis. There was marked amyotrophy, but without fasciculations. Sensation was intact apart from a hypo-aesthetic patch over the thigh. Electrophysiological investigations showed an active motor axonopathy. Urinary porphyrins, δ-aminolaevulinic acid and porphobilinogen were elevated. Mutation analysis revealed the c445C>T (R149X) mutation in the porphobilinogen deaminase gene. The patient responded dramatically to haem arginate and could walk with assistance 2 weeks later. We identified the first molecularly confirmed acute intermittent porphyria in a black South African. The clinical presentation mimicked a progressive lower motor neuron syndrome.