11 research outputs found
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 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 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.http://www.nature.com/ejhg/index.htm
A case for genomic medicine in South African paediatric patients with neuromuscular disease
DATA AVAILABILITY STATEMENT : The original contributions presented in the study are
included in the article/Supplementary Material, further
inquiries can be directed to the corresponding author/s.Paediatric neuromuscular diseases are under-recognised and under-diagnosed
in Africa, especially those of genetic origin. This may be attributable to various
factors, inclusive of socioeconomic barriers, high burden of communicable
and non-communicable diseases, resource constraints, lack of expertise in
specialised fields and paucity of genetic testing facilities and biobanks in the
African population, making access to and interpretation of results more
challenging. As new treatments become available that are effective for specific
sub-phenotypes, it is even more important to confirm a genetic diagnosis for
affected children to be eligible for drug trials and potential treatments. This
perspective article aims to create awareness of the major neuromuscular
diseases clinically diagnosed in the South African paediatric populations, as
well as the current challenges and possible solutions. With this in mind, we
introduce a multi-centred research platform (ICGNMD), which aims to address
the limited knowledge on NMD aetiology and to improve genetic diagnostic
capacities in South African and other African populations.The National Health Laboratory Services (NHLS) of South Africa; the South African Medical Research Council (SAMRC), The genetics of Neuromuscular Diseases in South African patient populations: the ICGNMD study as well as the National Research Foundation (NRF) of South Africa.https://www.frontiersin.org/journals/pediatricsam2023Paediatrics and Child Healt
An investigation into the origin of acyl-amino acid conjugation in the human and bovine metabolism
PhD (Biochemistry), North-West University, Potchefstroom CampusGlycine conjugation and subsequent excretion of carboxylic acids of endogenous and
exogenous origin is a normal detoxication process. A wide variety of short- and medium-chain, mono and dicarboxyl, acylglycine conjugates are also excreted in the urine of patients
suffering from various metabolic disorders. The formation of these conjugates is catalyzed by
glycine N-acyltransferase (EC 2.3.1.13). During the last two decades acylarnino acid
conjugates with amino acid moieties other than glycine have also been detected in the urine of
patients with metabolic disorders. These include propionylalanine, propionylglutamic acid,
benzoylalanine, isovalerylalanine, isovalerylglutamic acid, and 3-methylcrotonylglutamic
acid. This study investigated the conjugation of benzoyl-CoA with the aliphatic and acidic
amino acids as well as their amides by glycine N-acyltransferase. Bovine and human glycine
N-acyltransferase was purified from liver mitochondria in a five-step strategy and conjugation
was investigated using these preparations in addition to mitochondrial lysates. A new
electrospray ionization tandem mass spectrometry-based method was developed to
characterize as well as quantify benzoylamino acid conjugation. Bovine glycine N-acyltransferase conjugated benzoyl-CoA with glycine (KmGiy = 6.2 mM), asparagine (KmAsn =
129 mM), glutamine (KmGJn = 353 mM), alanine (KmAJa = 1573 mM), and glutamic acid
(KmGiu = 1148 mM) in a sequential mechanism. Benzoyl conjugation with serine was also
detected. Human glycine N-acyltransferase, on the other hand, showed a less diverse amino
acid substrate utilization and conjugated benzoyl-CoA with glycine (KmGiy = 6.4 mM),
alanine (KmAJa = 998 mM), as well as glutamic acid. The results indicated that, compared to
glycine, all other amino acids conjugated with benzoyl-CoA at much lower rates, which
explains the relative low levels of the newly detected conjugates in urine. Inhibition of
human and bovine glycine N-acyltransferase by benzoylamino acid conjugates other than
glycine were much lower compared to benzoylglycine and it is unlikely to have an inhibitory
effect on glycine N-acyltransferase in vivo.
A human liver cDNA clone was obtained using bovine N-terminal sequence data which
shared a strong homology (82 % ) with bovine GNAT cDNA as well as bovine glutarnine N-phenylacetyltransferase cDNA (77 %). Attempts to express the cDNA in E.coli were not
successful and the identity of this cDNA could therefore not be confirmed.Doctora
Combined tarsal and carpal tunnel syndrome in Mucolipidosis Type III : a case study and review
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. Sixtythree
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 encephalomyopath
Glycation of fibrinogen in uncontrolled diabetic patients and the effects of glycaemic control on fibrinogen glycation
Evidence exists for a relationship between glycaemic control and macrovascular disease. Non-enzymatic glycation of proteins may explain this relationship in part. We investigated the effect of blood glucose control, under out-patient conditions, on fibrinogen glycation as well as the relationship between glycated fibrinogen and glycaemic control using a new sensitive method for the measurement of glycated fibrinogen.The authors would like to thank the volunteers who took part in the study for their willingness and effort. We would also like to thank Sr. Dorothy Kekana for her hard work in recruiting subjects and in the execution of the intervention. Many thanks also to Dr. Rustem Litvinov and Dr. Robert Ariëns, for their expertise and input in analytic experiments and results. The study was funded by research funds from the North-West University and the University of Pretoria. Insulin was provided by Sanofi-Aventis, South Africa and Novo-Nordisk, South Africa and glucometers by Roche Diagnostics
Glycaemic control improves fibrin network characteristics in type 2 diabetes : a purified fibrinogen model
Diabetic subjects have been shown to have altered fibrin network structures.One proposed mechanism for this is non-enzymatic glycation of fibrinogen due to high blood glucose.We investigated whether glycaemic control would result in altered fibrin network structures due to decreased fibrinogen glycation. Twenty uncontrolled type 2 diabetic subjects were treated with insulin in order to achieve glycaemic control. Twenty age- and body mass index (BMI)-matched non-diabetic subjects were included as a reference group. Purified fibrinogen, isolated from plasma samples was used for analysis.There was a significant decrease in fibrinogen glycation (6.81 to 5.02 mol glucose/mol fibrinogen) with a corresponding decrease in rate of lateral aggregation (5.86 to 4.62) and increased permeability (2.45 to 2.85 x 10–8 cm2) and lysis rate (3.08 to 3.27 μm/min) in the diabetic subjects after glycaemic control.These variables correlated with markers of glycaemic control. Fibrin clots of non-diabetic subjects had a significantly higher ratio of inelastic to elastic deformation than the diabetic subjects (0.10 vs. 0.09). Although there was no difference in median fiber diameter between diabetic and non-diabetic subjects, there was a small increase in the proportion of thicker fibers in the diabetic samples after glycaemic control. Results from SDS-PAGE indicated no detectable difference in factor XIIIa-crosslinking of fibrin clots between uncontrolled and controlled diabetic samples. Diabetic subjects may have altered fibrin network formation kinetics which contributes to decreased pore size and lysis rate of fibrin clots. Achievement of glycaemic control and decreased fibrinogen glycation level improves permeability and lysis rates in a purified fibrinogen model