[Pernicious anemia with false normal vitamin B12 levels caused by intrinsic factor antibodies interference: a case report]. / Maladie de Biermer avec dosage de vitamine B12 faussement normal par interférence avec les anticorps anti-facteur intrinsèque : à propos d'un cas.

We present a case of a 48-year-old woman with a fortuitous discovery of macrocytic anemia and thrombocytopenia. Serum folate and vitamin B12 levels were normal. However, due to the presence of indirect signs of cobalamin deficiency, such as elevated homocysteine and methylmalonic acid, and signs of dyserythropoiesis on the bone marrow aspirate, pernicious anemia was suspected. Vitamin B12 dosage was repeated finding fluctuating but always normal results. Anti-intrinsic factor antibodies were present at a very high level, explaining the fluctuations and the interference found on the assay using competitive binding chemiluminescence (CBLA). Serum vitamin B12 dosage by electrochemiluminescence, a method described as not interfering with intrinsic factor antibodies, showed a collapsed vitamin B12 level. Measurement of vitamin B12 with CBLA after adsorption of immunoglobulins in the sample using protein G SepharoseTM, confirmed the interference of the cobalamin assay with autoantibodies. This case illustrates the difficulties regarding the analysis and standardization of the vitamin B12 assay for the diagnosis of pernicious anemia.

Class 3 PI3K coactivates the circadian clock to promote rhythmic de novo purine synthesis.

Metabolic demands fluctuate rhythmically and rely on coordination between the circadian clock and nutrient-sensing signalling pathways, yet mechanisms of their interaction remain not fully understood. Surprisingly, we find that class 3 phosphatidylinositol-3-kinase (PI3K), known best for its essential role as a lipid kinase in endocytosis and lysosomal degradation by autophagy, has an overlooked nuclear function in gene transcription as a coactivator of the heterodimeric transcription factor and circadian driver Bmal1-Clock. Canonical pro-catabolic functions of class 3 PI3K in trafficking rely on the indispensable complex between the lipid kinase Vps34 and regulatory subunit Vps15. We demonstrate that although both subunits of class 3 PI3K interact with RNA polymerase II and co-localize with active transcription sites, exclusive loss of Vps15 in cells blunts the transcriptional activity of Bmal1-Clock. Thus, we establish non-redundancy between nuclear Vps34 and Vps15, reflected by the persistent nuclear pool of Vps15 in Vps34-depleted cells and the ability of Vps15 to coactivate Bmal1-Clock independently of its complex with Vps34. In physiology we find that Vps15 is required for metabolic rhythmicity in liver and, unexpectedly, it promotes pro-anabolic de novo purine nucleotide synthesis. We show that Vps15 activates the transcription of Ppat, a key enzyme for the production of inosine monophosphate, a central metabolic intermediate for purine synthesis. Finally, we demonstrate that in fasting, which represses clock transcriptional activity, Vps15 levels are decreased on the promoters of Bmal1 targets, Nr1d1 and Ppat. Our findings open avenues for establishing the complexity for nuclear class 3 PI3K signalling for temporal regulation of energy homeostasis.

Cholesterol accumulation induced by acetylated LDL exposure modifies the enzymatic activities of the TCA cycle without impairing the respiratory chain functionality in macrophages.

The unregulated uptake of modified low-density lipoproteins (LDL) by macrophages leads to foam cell formation, promoting atherosclerotic plaque progression. The cholesterol efflux capacity of macrophages by the ATP-Binding Cassette transporters depends on the ATP mitochondrial production. Therefore, the mitochondrial function maintenance is crucial in limiting foam cell formation. Thus, we aimed to investigate the mechanisms involved in the mitochondrial dysfunction that may occur in cholesterol-laden macrophages. We incubated THP-1 macrophages with acetylated LDL (acLDL) to obtain cholesterol-laden cells or with mildly oxidized LDL (oxLDL) to generate cholesterol- and oxidized lipids-laden cells. Cellular cholesterol content was measured in each condition. Mitochondrial function was evaluated by measurement of several markers of energetic metabolism, oxidative phosphorylation, oxidative stress, mitochondrial biogenesis and dynamics. OxLDL-exposed macrophages exhibited a significantly reduced mitochondrial respiration and complexes I and III activities, associated to an oxidative stress state and a reduced mitochondrial DNA copy number. Meanwhile, acLDL-exposed macrophages featured an efficient oxidative phosphorylation despite the decreased activities of aconitase, isocitrate dehydrogenase and α-ketoglutarate dehydrogenase. Our study revealed that mitochondrial function was differently impacted according to the nature of modified LDL. Exposure to cholesterol and oxidized lipids carried by oxLDL leads to a mitochondrial dysfunction in macrophages, affecting the mitochondrial respiratory chain functional capacity, whereas the cellular cholesterol enrichment induced by acLDL exposure results in a tricarboxylic acid cycle shunt while maintaining mitochondrial energetic production, reflecting a metabolic adaptation to cholesterol intake. These new mechanistic insights are of direct relevance to the understanding of the mitochondrial dysfunction in foam cells.

Noninvasive Prenatal Diagnosis of a Paternally Inherited MEN1 Pathogenic Splicing Variant.

CONTEXT: Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disease caused by mutations in the tumor suppressor gene MEN1. The uncertainty of pathogenicity of MEN1 variants complexifies the selection of the patients likely to benefit from specific care. OBJECTIVE: MEN1-mutated patients should be offered tailored tumor screening and genetic counseling. We present a patient with hyperparathyroidism for whom genetic analysis identified a variant of uncertain significance in the MEN1 gene (NM_130799.2): c.654G > T p.(Arg218=). Additional functional genetic tests were performed to classify the variant as pathogenic and allowed prenatal testing. DESIGN: Targeted next generation sequencing identified a synonymous variant in the MEN1 gene in a 26-year-old male with symptomatic primary hyperparathyroidism. In silico and in vitro genetic tests were performed to assess variant pathogenicity. RESULTS: Genetic testing of the proband's unaffected parents showed the variant occurred de novo. Transcript study showed a splicing defect leading to an in-frame deletion. The classification of the MEN1 variant as pathogenic confirmed the diagnosis of MEN1 and recommended an adapted medical care and follow-up. Pathogenic classification also allowed to propose a genetic counseling to the proband and his wife. Noninvasive prenatal diagnosis was performed with a personalized medicine-based protocol by detection of the paternally inherited variant in maternal plasmatic cell free DNA, using digital PCR. CONCLUSION: We showed that functional genetic analysis can help to assess the pathogenicity of a MEN1 variant with crucial consequences for medical care and genetic counseling decisions.

Prenatal-onset of congenital neuronal ceroid lipofuscinosis with a novel CTSD mutation.

BACKGROUND: Neuronal ceroid lipofuscinoses (NCLs) form a clinically and genetically heterogeneous group of inherited neurodegenerative disorders that share common neuropathological features. Although they are the first cause of neurodegenerative disorders in children, their congenital forms are rarely documented. They are classically due to mutations in the CTSD gene (the CLN10 disease). Affected newborns usually present severe microcephaly, seizures and respiratory failure leading to death within the first postnatal days or weeks. CASES: We report on two siblings, in which exome sequencing identified a novel homozygous CTSD variant. The first sib presented at birth with seizures, rapidly progressive postnatal microcephaly and visual deficiency related to retinal dysfunction. Progressive neurological deterioration leads to death at the age of 24 months. Cathepsin D activity was reduced in the cultured fibroblasts of this patient. The second sib, a fetus of 36 weeks of gestation, was delivered after pregnancy termination for brain abnormalities (in accordance with French Legislation) suggesting a recurrence of the disease. Fetal postmortem examination disclosed neuropathological features consistent with NCL. CONCLUSIONS: Congenital NCL related to CTSD mutations is a neuronal storage disorder that produces in the developing brain diffuse neurodegeneration and white matter atrophy resulting in a progressive and rapidly lethal microcephaly.

Prenatal features and neonatal management of severe hyperparathyroidism caused by the heterozygous inactivating calcium-sensing receptor variant, Arg185Gln: A case report and review of the literature.

BACKGROUND: Loss-of-function variants in the calcium-sensing receptor (CASR) gene are known to be involved in a clinical spectrum ranging from asymptomatic familial hypocalciuric hypercalcemia (FHH) to neonatal severe hyperparathyroidism (NSHPT). Homozygous or compound heterozygous variants are usually responsible for severe neonatal forms, whereas heterozygous variants cause benign forms. One recurrent pathogenic variant, p.Arg185Gln, has been reported in both forms, in a heterozygous state. This variant can be a de novo occurrence or can be inherited from a father with FHH.NSHPT leads to global hypotonia, failure to thrive, typical X-ray anomalies (diffuse demineralization, fractures, metaphyseal irregularities), and acute respiratory distress which can be fatal. Phosphocalcic markers show severe hypercalcemia, abnormal urinary calcium resorption, and hyperparathyroidism as major signs.Classical treatment involves calcium restriction, hyperhydration, and bisphosphonates. Unfortunately, the disease often leads to parathyroidectomy. Recently, calcimimetics have been used with variable efficacy. Efficacy in NSHPT seems to be particularly dependent on CASR genotype. CASE PRESENTATION: We describe the antenatal presentation of a male with short ribs, initially suspected having skeletal ciliopathy. At birth, he presented with NSHPT linked to the pathogenic heterozygous CASR variant, Arg185Gln, inherited from his father who had FHH. Postnatal therapy with cinacalcet was successful. DISCUSSION: An exhaustive literature review permits a comparison with all reported cases of Arg185Gln and to hypothesize that cinacalcet efficacy depends on CASR genotype. This confirms the importance of pedigree and parental history in antenatal short rib presentation and questions the feasibility of phosphocalcic exploration during pregnancy or prenatal CASR gene sequencing in the presence of specific clinical signs. It could in fact enable early calcimimetic treatment which might be effective in the CASR variant Arg185Gln.

Troponin elevation in other conditions than acute coronary syndromes.

Troponin is a specific cardiac infarction isoform (TnIc, TnTc) and its determination is used for the diagnosis of myocardial infarction even with normal Electrocardiography. The increase of cardiac troponins occurs in a variety of clinical situations without an acute coronary syndrome (ACS), cardiologists and emergency physicians are often confronted with positive troponins that are difficult to interpret. Few data exist about the occurrence, the clinical characteristics and the predictive value in case of absence of ACS. The objective of this study is to present the main extracardiac causes responsible of the increase of TnIc. We present some clinical cases that illustrate this diagnostic problem. A troponin elevation is observed in myopericarditis, renal failure, heart failure, pulmonary embolism, septic shock, rhabdomyolysis, stroke and others where there is a myocardial damage unrelated to coronary occlusion. Many cases of false positives, which raise the possibility of analytical interferences, must be identified.