Search

Folate and vitamin B12 are needed for the proper embryo-fetal development possibly through their interacting role in the 1-carbon metabolism. Folate fortification reduces the prevalence of complex birth defects, and more specifically neural tube defects (NTDs). GIF and FUT2 are 2 genes associated with the uptake and blood level of vitamin B12. We evaluated GIF and FUT2 as predictors of severe birth defects, in 183 aborted fetuses compared with 375 healthy newborns. The GIF290C allele frequency was estimated to 0.4% in healthy newborns and to 8.1% in NTD fetuses (odds ratio 17.8 [95% confidence interval CI: 4.0-77.6]). The frequency of FUT2 rs601338 secretor variant was not different among groups. The GIF 290C heterozygous/ FUT2 rs601338 secretor variant combined genotype was reported in 6 of the 37 NTD fetuses, but not in other fetuses and healthy newborns ( P < .0001). This GIF/ FUT2 combined genotype has been previously reported in children with congenital gastric intrinsic factor (GIF) deficiency, with respective consequences on B12 binding activity and GIF secretion. In conclusion, a genotype reported in congenital GIF deficiency produces also severe forms of NTD. This suggests that vitamin B12 delivery to neural tissue by the CUBN/GIF pathway could play a role in the neural tube closure mechanisms. [ABSTRACT FROM AUTHOR]

Moizard M-P, Ronce N, Blesson S, Bieth E, Burglen L, Mignot C, Mortemousque I, Marmin N, Dessay B, Danesino C, Feillet F, Castelnau P, Toutain A, Moraine C, Raynaud M. Twenty-five novel mutations including duplications in the ATP7A gene. Menkes disease (MD) and occipital horn syndrome (OHS) are allelic X-linked recessive copper deficiency disorders resulting from ATP7A gene mutations. MD is a severe condition leading to progressive neurological degeneration and death in early childhood, whereas OHS has a milder phenotype with mainly connective tissue abnormalities. Until now, molecular analyses have revealed only deletions and point mutations in both diseases. This study reports new molecular data in a series of 40 patients referred for either MD or OHS. We describe 23 point mutations (9 missense mutations, 7 splice site variants, 4 nonsense mutations, and 3 small insertions or deletions) and 7 intragenic deletions. Of these, 18 point mutations and 3 deletions are novel. Furthermore, our finding of four whole exon duplications enlarges the mutation spectrum in the ATP7A gene. ATP7A alterations were found in 85% of cases. Of these alterations, two thirds were point mutations and the remaining one third consisted of large rearrangements. We found that 66.6% of point mutations resulted in impaired ATP7A transcript splicing, a phenomenon more frequent than expected. This finding enabled us to confirm the pathogenic role of ATP7A mutations, particularly in missense and splice site variants. [ABSTRACT FROM AUTHOR]

We report the case of a 33-year-old man who presented with headaches and vomiting. Soon after admission he became drowsy and agitated, developed ventricular tachycardia and his neurological state worsened (Glasgow coma score 6). Blood analysis showed respiratory alkalosis, hyperlactacidemia (8 mmol/l), hyperammonemia (390 micro mol/l) and hypoglycaemia (2.4 mmol/l). Subsequently, he developed supraventricular tachycardia, ventricular tachycardia and ultimately ventricular fibrillation resulting in cardiac arrest, which was successfully treated. A CT scan of the head revealed cerebral oedema. Whilst in the intensive care unit, he developed renal failure and rhabdomyolysis. The metabolic abnormalities seen at the time of admission normalised within 48 h with IV glucose infusion. Biological investigations, including urinary organic acids and plasma acylcarnitines, showed results compatible with MCAD deficiency. Mutation analysis revealed the patient was homozygous for the classical mutation A985G. This is one of only a few reports of severe cardiac arrhythmia in an adult due to MCAD deficiency. This condition is probably under-diagnosed in adult patients with acute neurological and/or cardiac presentations. [ABSTRACT FROM AUTHOR]

Abstract: Background: Deficiency of mitochondrial trifunctional protein (MTP) is caused by mutations in the HADHA and HADHB genes, which have been mostly delineated at the genomic DNA level and have not been always elucidated. Aim: To identify mutations in a French cohort of 52 MTP deficient patients and the susceptibility of mutations generating premature termination codons (PTCs) to the nonsense mRNA mediated decay (NMD). Methods: Mutation screening in fibroblasts was performed at the cDNA level and real-time RT-PCR was used to compare the levels of the different PTC-bearing mRNAs before and after a treatment of fibroblasts by emetine, a translation inhibitor. Results: A mutation detection rate of 100% was achieved. A total of 22 novel mutations were identified, including a large-sized genomic deletion in HADHB gene. A high proportion of all identified mutations were non-sense, frameshift and splicing mutations, generating (PTCs), distributed essentially on HADHA coding regions. We could demonstrate that the majority of mutations resulting in PTCs conform to the established rules governing the susceptibility to NMD. Conclusion: Our results emphasize the value of cDNA analysis in the characterization of HADHA and HADHB mutations and further strengthen the model of haploinsufficiency as a major pathomechanism in MTP defects. [Copyright &y& Elsevier]

Recurrent rhabdomyolysis episodes in adults are commonly caused by glycogenosis or fatty-acid oxidation disorders. However, in many cases the etiology remains unknown, and recently mutations in RYR1 appeared as a possible cause of exercise induced rhabdomyolysis. We studied 14 adults who presented acute rhabdomyolysis (CK above 10,000 UI/l) triggered by exercise or fever, in whom McArdle disease, fatty acid oxidation disorders, and LPIN1 mutations were excluded. All patients underwent muscle biopsy in order to screen RYR1 mutation on cDNA. Potentially pathogenic mutations in RYR1 gene were detected in 5 unrelated patients. Mutations were the following: p.Val4847Leu, p.G593R, p R3539H, Gly2434Arg, p.Gln3461Pro, p.A1352T, p.A933T and p.Ser1342Gly. Two patients presented each 2 and 3 heterozygous variants. Baseline CK levels were elevated in all cases but one (400–700 UI/l). None of them complained of myalgia or exercise intolerance. Rhabdomyolysis were triggered by weight-training in two patients, viral infection in two cases, and retinoic acid treatment in the last case. Higher recorded CK levels were between 28,000 and 94,000 UI/l, without renal failure. Three patients had a unique episode, whereas two other had several rhabdomyolysis episodes. Muscle biopsies were either normal, or showed moderate structure disorganization. Two siblings of a patient, the father of another patient, and the brother of a third patient, also presented mutations in the RYR1 gene and high baseline CK level. Per-anesthetic malignant hyperthermia was noticed in a grand-mother of one patient. Mutations in RYR1 gene should be systematically searched in patients with exercise or fever induced rhabdomyolysis episodes, after having excluded common metabolic disorders. This diagnostic implies major consequences for genetic counselling in the families, due to the potential risk of anesthetic malignant for the patients and their relatives. [ABSTRACT FROM AUTHOR]