Laura Adobbati

Retrospective study of a large population of patients affected with mitochondrial disorders: clinical, morphological and molecular genetic evaluation.

Abstract Mitochondrial disorders are human genetic diseases with extremely variable clinical and genetic features. To better define them, we made a genotype-phenotype correlation in a series of 207 affected patients, and we examined most of them with six laboratory examinations (serum CK and basal lactate levels, EMG, cardiac and EEG studies, neuroradiology). We found that, depending on the genetic abnormality, hyperckemia occurs most often with either chronic progressive external ophthalmoplegia (CPEO) and ptosis or with limb weakness. Myopathic EMGs are more common than limb weakness, except in patients with A8344G mutations. Peripheral neuropathy, when present, is always axonal. About 80 % of patients with A3243G and A8344G mutations have high basal lactate levels, whereas pure CPEO is never associated with increased lactate levels. Cardiac abnormalities mostly consist of conduction defectsAbnormalities on CT or MRI of the brain are relatively common in A3243G mutations independently of the clinical phenotype. Patients with multiple mtDNA deletions are somehow “protected” against the development of abnormalities with any of the tests. We conclude that, despite the phenotypic heterogeneity of mitochondrial disorders, correlation of clinical features and laboratory findings may give the clinician important clues to the genetic defect, allowing earlier diagnosis and counselling.

Novel Twinkle (PEO1) gene mutations in mendelian progressive external ophthalmoplegia

Multiple deletions of mitochondrial DNA (mtDNA) are associated with different mitochondrial disorders inherited as autosomal dominant and recessive traits. Causative mutations have been found in five genes, mainly involved in mtDNA replication and stability. They include POLG1, the gene encoding the catalytic subunit of mtDNA polymerase (polγ), POLG2 encoding its accessory subunit, ANT1 coding the adenine nucleotide translocator and PEO1 which codes for Twinkle, the mitochondrial helicase. Finally OPA1 missense mutations are involved in phenotypes presenting optic atrophy as a major feature.To define the relative contribution of POLG1, POLG2, ANT1 and PEO1 genes to the mtDNA multiple deletion syndromes, we analysed them in a cohort of 67 probands showing accumulation of multiple mtDNA deletions in muscle. The patients were predominantly affected with a mitochondrial myopathy with or without progressive external ophthalmoplegia (PEO). Genetic analysis revealed that 1) PEO1 has a major role in determining familial PEO, since it accounts for 26.8 % of familial cases, followed by ANT1 (14.6 %) and POLG1 (9.8 %); 2) no mutations in any of the known genes were found in 53.7 % of probands of this series. Six novel missense mutations contributing to the mutational load of PEO1 gene (p.R334P, p.W315S, p. S426N, p.W474S, p.F478I, p.E479K) were associated with an adult onset PEO phenotype.

High-dose intravenous human immunoglobulin in polymyositis resistant to treatment

Two patients were treated with treatment-resistant polymyositis with intravenous immunoglobulin over four days at a dose of 0.4 g/kg/day. Clinical recovery followed within two months. Serum creatine kinase (CK) activity decreased to normal, and a clear improvement in muscle strength was observed. One patient showed neither clinical relapses nor increase in serum CK activity after 20 months. The other showed a mild increase in serum CK activity after 24 months and was successfully retreated with intravenous immunoglobulin. There were no significant adverse side effects.

Cytochrome c oxidase during human fetal development

Histochemical, biochemical and immunologic analysis of cytochrome c oxidase (COX) in skeletal muscle, heart and kidney during human fetal development was performed. COX histochemical activity was present only in few muscle fibres from the 11th to the 20th week of gestation. At the same developmental stage intrafusal muscle fibres, heart and kidney already showed strong activity. At the 28th week of gestation muscular COX activity was present in about 90% of the fibres. Tissue biochemical analysis confirmed these histochemical findings. Histochemical and biochemical findings compared to the immunocytochemical results and ELISA indicate that COX activity parallels the progressive synthesis of the enzyme in each tissue.

NOTCH3 gene mutations in subjects clinically suspected of CADASIL

BACKGROUND Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited cerebrovascular disease due to mutations involving loss or gain of a cysteine residue in the NOTCH3 gene. A cluster of mutations around exons 3 and 4 was originally reported. Identification of pathogenic mutation is important for diagnostic confirmation of the disease, however genetic counselling and testing of relatives at risk is critical in mutation carriers. METHODS Mutation analysis of the NOTCH3 gene was performed through direct sequencing in 140 patients with clinical suspicion of CADASIL. Patients underwent genetic counselling pre and post testing. The 2-23 exons containing all EGF-like domains were screened. RESULTS 14 familial forms of the disease have been identified with 14 different causative mutations in exons 2, 3, 4, 5, 7, 10, 14, 19, 20 and 22 of the NOTCH3 gene; no pathogenetic mutations have been identified in exons 6 and 8; several genetic variations both in coding as well as in intronic regions were identified too. CONCLUSIONS Our data confirm the importance of screening the whole EGF-like domains region of NOTCH3 gene for the molecular diagnosis of CADASIL among the Italian population too. Moreover genetic variants different from loss or gain of a cysteine residue are identified and presented.

Carotid artery stenting in patients with acute coronary syndrome: a possible primary therapy for symptomatic carotid stenosis

Purpose To report the results of carotid artery stenting (CAS) in symptomatic patients (stroke/transient ischemic attack) after recent percutaneous transluminal coronary angioplasty (PTCA) for acute coronary syndrome (ACS). Methods Between January 2009 and July 2011, 28 consecutive patients (18 women; mean age 66 years, range 42–82) underwent protected CAS for symptomatic carotid stenosis following recent PTCA that included bare or drug-eluting stents requiring uninterrupted dual antiplatelet therapy. Primary technical success, neurological complications, major adverse cardiovascular events, and death were evaluated at 30 days and over midterm follow-up. Results Technical success was 96%; 1 patient suffered a nonfatal major stroke (3.5% 30-day stroke rate) during the procedure. During a median 21.6-month follow-up, 4 (14%) patients died of myocardial infarction (all diabetic smokers with ejection fractions <40%), but there were no new neurological events. Estimated survival was 89.3% at 2 years. Further coronary interventions were performed in 2 diabetic patients with a body mass index >34 kg/m2. Conclusion This preliminary experience demonstrated that CAS is a reasonable, safe, and effective treatment for patients with symptomatic carotid artery stenosis who were recently treated with coronary stents requiring uninterrupted dual antiplatelet therapy.

APS and the nervous system

Cerebrovascular disease is the most frequent clinical manifestation of the antiphospholipid syndrome (APS) at disease onset, after deep venous thrombosis. At a 10-year follow-up, it represents the overall most common clinical event related to antiphospholipid antibodies (aPL). Besides thrombotic events affecting brain circulation, a wide range of “non-criteria” neurological manifestations has been associated with aPL such as dementia, epilepsy, chorea, headache, multiple sclerosis, myelopathy, peripheral neuropathy, hearing loss, and ocular syndromes. aPL display a particular tropism for cerebral circulation, which might be partially explained by the peculiarity of brain endothelial cells. However, aPL might induce neurological manifestations not only because of pro-thrombotic mechanisms but also because they can bind to neurons and astrocytes, disrupting their function. Ischemic manifestations of APS always require the initiation of either antiplatelet drugs or long-term anticoagulants; no standard treatment is available for nonvascular neurological manifestations of APS. The wide heterogeneity in neurological presentation of APS represents a challenge for clinicians: it is important to promptly recognize and effectively treat them in early stages, in order to avoid diagnostic and therapeutic delay.