The present work presents a “from gene defect to clinics” pathogenesis study of a patient with a hitherto unreported mutation in the CPT1A gene. In early childhood, the patient developed a ...life-threatening episode (hypoketotic hypoglycemia, liver cytolysis, and hepatomegaly) evocative of a mitochondrial fatty acid oxidation disorder, and presented deficient fibroblast carnitine palmitoyltransferase 1 (CPT1) activity and homozygosity for the c.1783 C > T nucleotide substitution on exon 15 of CPT1A (p.R595W mutant). While confirming CPT1A deficiency, whole blood de novo acylcarnitine synthesis and the levels of carnitine and its esters formally linked intracellular free-carnitine depletion to intracellular carnitine esterification. Sequence alignment and modeling of wild-type and p.*R595W CPT1A proteins indicated that the Arg595 targeted by the mutated codon is phylogenetically well conversed. It contributes to a hydrogen bond network with neighboring residues Cys304 and Met593 but does not participate in the catalysis and carnitine pocket. Its replacement by tryptophan induces steric hindrance with the side chain of Ile480 located in α-helix 12, affecting protein architecture and function. This hindrance with Ile480 is also originally described with tryptophan 304 in the known mutant p.C304W CPT1A, suggesting that the mechanisms that invalidate CPT1A activity and underlie pathogenesis could be common in both the new (p.R595W) and previously described (p.C304W) mutants.
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FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
REG4, the latest member of the regenerating gene family, is overexpressed in inflammatory bowel diseases and gastrointestinal carcinomas. To date, its pathophysiologic role has not been well ...established. Using HT-29 models, we previously identified REG4 as being overexpressed in colorectal tumor cells displaying a drug-resistance phenotype; some also displayed invasive properties. Thus, we investigated the potential functions of REG4 in biological processes involved in colorectal tumor progression such as cell proliferation, migration and invasion. Colon cancer cells secreting REG4 (HT29-5M21, HT29-5F7 and HT29/REG4-8) or not (HT-29, HT29/CT1 and Caco-2/TC7) were used to analyze the autocrine and paracrine effects of REG4. REG4 was continuously secreted into the culture medium of colon cancer cells. REG4 stimulated cell growth in a paracrine manner after 24 h of treatment. Notably, REG4 promoted migration and invasion of tumor cells in both an autocrine and paracrine manner, and these effects were significantly decreased by concomitant treatment with an anti-REG4 antibody. Using pharmacological inhibitors, we showed that PI3K/Akt, PKAs, PKCs and Rho-like GTPases, but not MAPK, are involved in REG4 invasion signals. In addition, REG4 expression was found to be increased in tissues harboring proliferation and migration properties such as the developing intestine and tissues from inflammatory bowel disease, hyperplastic polyps, adenoma and colorectal cancers. In various situations, REG4 expression was not confined to proliferating cells, regenerating cells or cells of the invasive front of metastatic tumors, suggesting that extracellular REG4 may act on epithelial cells in a paracrine manner. Altogether, our results indicate that REG4 is a multifunctional secreted protein which acts on colorectal cancer cells in an autocrine and paracrine manner. According to its biological functions and tissue expression, REG4 may play an important role in the development and progression of colorectal cancer, as well as in intestinal morphogenesis and epithelium restitution.
Inborn errors of metabolism (IEM) are rare diseases caused by mutations in genes encoding enzymes or carriers. Qualitative or quantitative protein deficiency induces both an accumulation of precursor ...metabolites and a lack of products downstream of the blockade. Pregnancy in patients with IEM is a condition likely to promote metabolic decompensation. In this review, we presented liver symptoms described during pregnancy in a context of hepatic IEM. In particular, we detailed clinical and biological abnormalities specifically occurring in tyrosinemia type I, Wilson disease, and main urea cycle defects. In the case of hepatic IEM, depending on the deficit, pregnant women have an increased risk of pre-eclampsia and HELLP syndrome, as well as hyperammonemia. Wilson disease, and principal urea cycle defects. Multidisciplinary consultation is essential for the optimal management of pregnant women with IEM as well as newborns.
The diagnosis of mitochondrial diseases is a real challenge because of the vast clinical and genetic heterogeneity. Classically, the clinical examination and genetic analysis must be completed by ...several biochemical assays to confirm the diagnosis of mitochondrial disease. Here, we tested the validity of microscale XF technology in measuring oxygen consumption in human skin fibroblasts isolated from 5 pediatric patients with heterogeneous mitochondrial disorders. We first set up the protocol conditions to allow the determination of respiratory parameters including respiration associated with ATP production, proton leak, maximal respiration, and spare respiratory capacity with reproducibility and repeatability. Maximum respiration and spare capacity were the only parameters decreased in patients irrespective of the type of OXPHOS deficiency. These results were confirmed by high-resolution oxygraphy, the reference method to measure cellular respiration. Given the fact that microscale XF technology allows fast, automated and standardized measurements, we propose to use microscale oxygraphy among the first-line methods to screen OXPHOS deficiencies.
A female patient, with normal familial history, developed at the age of 30 months an episode of diarrhoea, vomiting and lethargy which resolved spontaneously. At the age of 3 years, the patient ...re-iterated vomiting, was sub-febrile and hypoglycemic, fell into coma, developed seizures and sequels involving right hemi-body. Urinary excretion of hexanoylglycine and suberylglycine was low during this metabolic decompensation. A study of pre- and post-prandial blood glucose and ketones over a period of 24 hours showed a normal glycaemic cycle but a failure to form ketones after 12 hours fasting, suggesting a mitochondrial β-oxidation defect. Total blood carnitine was lowered with unesterified carnitine being half of the lowest control value. A diagnosis of mild MCAD deficiency (MCADD) was based on rates of 1-14C-octanoate and 9, 10-3H-myristate oxidation and of octanoyl-CoA dehydrogenase being reduced to 25% of control values. Other mitochondrial fatty acid oxidation proteins were functionally normal. De novo acylcarnitine synthesis in whole blood samples incubated with deuterated palmitate was also typical of MCADD. Genetic studies showed that the patient was compound heterozygous with a sequence variation in both of the two ACADM alleles; one had the common c.985A>G mutation and the other had a novel c.145C>G mutation. This is the first report for the ACADM gene c.145C>G mutation: it is located in exon 3 and causes a replacement of glutamine to glutamate at position 24 of the mature protein (Q24E). Associated with heterozygosity for c.985A>G mutation, this mutation is responsible for a mild MCADD phenotype along with a clinical story corroborating the emerging literature view that patients with genotypes representing mild MCADD (high residual enzyme activity and low urinary levels of glycine conjugates), similar to some of the mild MCADDs detected by MS/MS newborn screening, may be at risk for disease presentation.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
A female patient, with normal familial history, developed at the age of 30 months an episode of diarrhoea, vomiting and lethargy which resolved spontaneously. At the age of 3 years, the patient ...re-iterated vomiting, was sub-febrile and hypoglycemic, fell into coma, developed seizures and sequels involving right hemi-body. Urinary excretion of hexanoylglycine and suberylglycine was low during this metabolic decompensation. A study of pre- and post-prandial blood glucose and ketones over a period of 24 hours showed a normal glycaemic cycle but a failure to form ketones after 12 hours fasting, suggesting a mitochondrial beta-oxidation defect. Total blood carnitine was lowered with unesterified carnitine being half of the lowest control value. A diagnosis of mild MCAD deficiency (MCADD) was based on rates of 1-.sup.14.sup.C-octanoate and 9, 10-.sup.3.sup.H-myristate oxidation and of octanoyl-CoA dehydrogenase being reduced to 25% of control values. Other mitochondrial fatty acid oxidation proteins were functionally normal. De novo acylcarnitine synthesis in whole blood samples incubated with deuterated palmitate was also typical of MCADD. Genetic studies showed that the patient was compound heterozygous with a sequence variation in both of the two ACADM alleles; one had the common c.985A>G mutation and the other had a novel c.145C>G mutation. This is the first report for the ACADM gene c.145C>G mutation: it is located in exon 3 and causes a replacement of glutamine to glutamate at position 24 of the mature protein (Q24E). Associated with heterozygosity for c.985A>G mutation, this mutation is responsible for a mild MCADD phenotype along with a clinical story corroborating the emerging literature view that patients with genotypes representing mild MCADD (high residual enzyme activity and low urinary levels of glycine conjugates), similar to some of the mild MCADDs detected by MS/MS newborn screening, may be at risk for disease presentation.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Recommendations for urinary organic acids analysis Van Noolen, Laetitia; Acquaviva-Bourdain, Cécile; Dessein, Anne-Frédérique ...
Annales de biologie clinique (Paris),
10/2020, Volume:
78, Issue:
5
Journal Article
Peer reviewed
Biochemical diagnosis of hereditary metabolic diseases requires the detection and simultaneous identification of a large number of compounds, hence the interest in metabolic profiles. Organic acid ...chromatography allows the identification of several hundred compounds and the quantification of the main molecules of interest. As part of the accreditation process for medical biology examinations according to standard NF EN ISO 15189, the group from the French society for inborn errors of metabolism (SFEIM) recommends an approach to accredit organic acid chromatography. Validation parameters and recommendations are discussed in this specific framework.
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