Izelle Smuts

Combined Tarsal and Carpal Tunnel Syndrome in Mucolipidosis Type III

Mucolipidosis type III (MLIII) (MIM# 252600) is an uncommon autosomal recessive disorder that results from uridine 5′‐diphosphate‐N‐acetylglucosamine: lysosomal hydrolase N‐acetyl‐1‐phosphotransferase or UDP‐GlcNAc 1‐phophotransferase deficiency. Clinical manifestations include developmental delay, short stature and other structural abnormalities. Less common clinical features, such as carpal tunnel syndrome, claw hand deformities, trigger fingers, and claw toes have previously been reported, but no specific association with tarsal tunnel syndrome has been reported in the literature. Tarsal tunnel syndrome is caused by entrapment of the posterior tibialis nerve in the tunnel formed by the medial malleolus of the ankle and the flexor retinaculum. It causes pain in the heel and sole of the foot as well as abnormal sensation in the distribution area of nervus tibialis posterior. In adults, the most common cause described is a ganglion. The phenomenon is rare in children and the published series are small. This case report portrays the presentation of a young girl with breath‐holding spells secondary to painful bilateral tarsal tunnel syndrome and trigger fingers subsequently diagnosed with MLIII.

An overview of a cohort of South African patients with mitochondrial disorders

Mitochondrial disorders are frequently encountered inherited diseases characterized by unexplained multisystem involvement with a chronic, intermittent, or progressive nature. The objective of this paper is to describe the profile of patients with mitochondrial disorders in South Africa. Patients with possible mitochondrial disorders were accessed over 10 years. Analyses for respiratory chain and pyruvate dehydrogenase complex enzymes were performed on muscle. A diagnosis of a mitochondrial disorder was accepted only if an enzyme activity was deficient. Sixty-three patients were diagnosed with a mitochondrial disorder, including 40 African, 20 Caucasian, one mixed ancestry, and two Indian patients. The most important findings were the difference between African patients and other ethnicities: respiratory chain enzyme complexes CI+III or CII+III deficiencies were found in 52.5% of African patients, being of statistical significance (p value = 0.0061). They also presented predominantly with myopathy (p value = 0.0018); the male:female ratio was 1:1.2. Twenty-five (62.5%) African patients presented with varying degrees of a myopathy accompanied by a myopathic face, high palate, and scoliosis. Fourteen of these 25 also had ptosis and/or progressive external ophthalmoplegia. No patients of other ethnicities presented with this specific myopathic phenotype. Caucasian patients (16/20) presented predominantly with central nervous system involvement. Of the South African pediatric neurology patients, Africans are more likely to present with myopathy and CII+III deficiency, and Caucasian patients are more likely to present with encephalopathy or encephalomyopathy.

Characterization of mtDNA variation in a cohort of South African paediatric patients with mitochondrial disease

Mitochondrial disease can be attributed to both mitochondrial and nuclear gene mutations. It has a heterogeneous clinical and biochemical profile, which is compounded by the diversity of the genetic background. Disease-based epidemiological information has expanded significantly in recent decades, but little information is known that clarifies the aetiology in African patients. The aim of this study was to investigate mitochondrial DNA variation and pathogenic mutations in the muscle of diagnosed paediatric patients from South Africa. A cohort of 71 South African paediatric patients was included and a high-throughput nucleotide sequencing approach was used to sequence full-length muscle mtDNA. The average coverage of the mtDNA genome was 81±26 per position. After assigning haplogroups, it was determined that although the nature of non-haplogroup-defining variants was similar in African and non-African haplogroup patients, the number of substitutions were significantly higher in African patients. We describe previously reported disease-associated and novel variants in this cohort. We observed a general lack of commonly reported syndrome-associated mutations, which supports clinical observations and confirms general observations in African patients when using single mutation screening strategies based on (predominantly non-African) mtDNA disease-based information. It is finally concluded that this first extensive report on muscle mtDNA sequences in African paediatric patients highlights the need for a full-length mtDNA sequencing strategy, which applies to all populations where specific mutations is not present. This, in addition to nuclear DNA gene mutation and pathogenicity evaluations, will be required to better unravel the aetiology of these disorders in African patients.

Unsuitable blood glucose measuring devices in neonatal or paediatric acute care

A newborn baby with persistent neonatal jaundice developed severe septicaemia. Blood glucose monitoring using Accuchek(R) revealed persistently high values, but laboratory blood glucose testing showed no instance of true hyperglycaemia. She was found to have galactosaemia. The Accu-chek® glucose meter does not discriminate between blood galactose and glucose.

The dilemma of diagnosing coenzyme Q10 deficiency in muscle

BACKGROUND Coenzyme Q10 (CoQ10) is an important component of the mitochondrial respiratory chain (RC) and is critical for energy production. Although the prevalence of CoQ10 deficiency is still unknown, the general consensus is that the condition is under-diagnosed. The aim of this study was to retrospectively investigate CoQ10 deficiency in frozen muscle specimens in a cohort of ethnically diverse patients who received muscle biopsies for the investigation of a possible RC deficiency (RCD). METHODS Muscle samples were homogenized whereby 600 ×g supernatants were used to analyze RC enzyme activities, followed by quantification of CoQ10 by stable isotope dilution liquid chromatography tandem mass spectrometry. The experimental group consisted of 156 patients of which 76 had enzymatically confirmed RCDs. To further assist in the diagnosis of CoQ10 deficiency in this cohort, we included sequencing of 18 selected nuclear genes involved with CoQ10 biogenesis in 26 patients with low CoQ10 concentration in muscle samples. RESULTS Central 95% reference intervals (RI) were established for CoQ10 normalized to citrate synthase (CS) or protein. Nine patients were considered CoQ10 deficient when expressed against CS, while 12 were considered deficient when expressed against protein. In two of these patients the molecular genetic cause could be confirmed, of which one would not have been identified as CoQ10 deficient if expressed only against protein content. CONCLUSION In this retrospective study, we report a central 95% reference interval for 600 ×g muscle supernatants prepared from frozen samples. The study reiterates the importance of including CoQ10 quantification as part of a diagnostic approach to study mitochondrial disease as it may complement respiratory chain enzyme assays with the possible identification of patients that may benefit from CoQ10 supplementation. However, the anomaly that only a few patients were identified as CoQ10 deficient against both markers (CS and protein), while the majority of patients where only CoQ10 deficient against one of the markers (and not the other), remains problematic. We therefore conclude from our data that, to prevent possibly not diagnosing a potential CoQ10 deficiency, the expression of CoQ10 levels in muscle on both CS as well as protein content should be considered.

Viral Infections of the Central Nervous System

Viral-mediated central nervous system (CNS) disease is a complex spectrum of clinical syndromes that result from viral tropism and individual immune responses and genetic susceptibility of patients. The epidemiology of the pathogens is constantly influenced by the availability, or non-availability, of health care services; preventative strategies; and the process of globalization, with rapid movement of people, animals and products. It is further complicated by natural disasters, wars and changes in lifestyle. The effects of the neurotropic viruses are discussed against the background of the epidemiology. The pathogenesis is a chain of events with the point of departure when the virus enters the body to spread and reach the different sites of the CNS. The blood-brain barrier and blood-cerebrospinal fluid barrier are then overcome by captivating mechanisms. Once the different viruses have settled at the preferred site or sites, and have sidestepped the initial immune surveillance, the phases of injury commence. The cytopathic effect of the viruses elicits a para- and post-infectious inflammatory response and a vicious circle of continued damage, viral entry and inflammation results in a process not merely of inflammation, but of intense inflammation. The different clinical syndromes are then identifiable and should be interpreted against their own specific and appropriate epidemiological backgrounds. Clinicians face the challenge of problematic management decisions while awaiting results on gravely ill patients and differential diagnostic considerations have to be taken into account. Establishing a diagnosis is a two-tier process: first it requires the integration of cerebrospinal fluid findings, imaging results, electrophysiological studies, serology and ancillary blood tests, for example full blood count, liver function tests and other appropriate microbiological investigations, and then these should be correlated with the clinical condition of the patient. Treatment should be initiated as soon as possible. General treatment principles for stabilizing and maintaining vital functions are crucial and empiric treatment should be initiated as soon as possible. This usually includes a broad-spectrum antibiotic, such as third-generation cephalosporin and acyclovir. As soon as specific etiologies have been excluded antibiotics can be stopped. The use of acyclovir is discussed. In the last section of the chapter specific characteristics of the neurotropic viral families are summarized.

OP44 – 2555: The association of coenzyme Q10 deficiencies and respiratory chain disorders in South African patients

Objective Although coenzyme Q10 (CoQ10) deficiencies are heterogeneous it is often associated with mitochondrial respiratory chain disorders (RCD), specifically complex II+III (CII+II) deficiencies. The aim of this study was to investigate the association of defects in the biosynthesis of CoQ10 and associated RCD in South African patients. Methods A method to quantify CoQ10 in muscle was developed and standardized using isotope-dilution liquid chromatography-tandem mass spectrometry (LC-MS-MS). The CoQ10 quantification was then performed on 155 muscle specimens of patients who clinically qualified for respiratory chain enzymes analyses. Of these patients, 76 had confirmed RCD of which 29 patients had CII+III deficiencies. Ion Torrent next generation sequencing (NGS) was performed on 24 patients, which included nine patients with decreased and 15 with normal CoQ10 levels. Eighteen targeted genes involved in primary as well as secondary CoQ10 deficiencies were sequenced. Results CoQ10 was deficient in nine patients of which eight patients had CII+III deficiency. Race, age and gender did not have any influence on the CoQ10 levels. A total of 16 possible disease-causing variants were identified. Three novel compound heterozygous variants in three patients (two with deficient CoQ10 levels) were found in the ETFDH, COQ6 and COQ7 genes respectively. Protein analyses supported pathogenicity of the variants in the ETFDH and COQ6 genes. Conclusion Only RCD patients with confirmed CII+III enzyme deficiencies had statistically significant low muscle CoQ10 levels and at least two patients had novel compound heterozygous mutations in the ETFDH and COQ6 genes.