Adult-onset methylenetetrahydrofolate reductase deficiency.

Severe hyperhomocysteinemia (>100 µmol/L) is often associated with inborn errors of homocysteine metabolism. It manifests typically in neonatal period with developmental delay, hypotonia, feeding problems or failure to thrive. Adult-onset forms are rare and include less severe manifestations. Early diagnosis is crucial because effective treatment is available. A 23-year-old man presented with a 3-week history of speech and gait impairment, and numbness in lower limbs. Neurological examination revealed dysarthria, decreased vibratory sensation in both legs and appendicular and gait ataxia. Brain MRI revealed T2-hyperintense symmetric white matter lesions and cortical atrophy. He had folate and vitamin B12 deficiency, a markedly elevated serum homocysteine and low methionine. Despite vitamin supplementation homocysteine levels remained elevated. Molecular studies of 5,10-methylenetetrahydrofolate reductase (MTHFR) gene revealed a new pathogenic mutation (c.1003C>T (p.Arg335Cys)) and a polymorphism (C677T (p.Ala222Val)) associated with hyperhomocysteinemia, both in homozygosity. The patient started betaine with clinical and biochemical improvement.

Demyelinating disease of the central nervous system associated with Pembrolizumab treatment for metastatic melanoma.

Immune checkpoint inhibitors are used in metastatic melanoma with good efficacy and safety profile. We report the first case of an inflammatory demyelinating disease of the central nervous system during treatment with Pembrolizumab and discuss the evidence in the literature supporting its causative role. The patient had a good clinical recovery after intravenous steroids, plasma exchange and discontinuation of Pembrolizumab. Due to the expected increase in the importance of immune checkpoint inhibitors in cancer treatment, it is important to be aware of neurological adverse events, as early treatment usually leads to good clinical responses.

In silico analysis for predicting pathogenicity of five unclassified mitochondrial DNA mutations associated with mitochondrial cytopathies' phenotypes.

Mitochondrial DNA (mtDNA) mutations have been assigned as a major cause of genetic disease. When a novel sequence variation is found, it is necessary to evaluate its functional impact, usually requiring functional molecular studies. Given the fact that this approach is difficult to put in practice in a routine basis, it is possible to take advantage of the in silico tools available and predict protein/RNA structure changes and therefore pathogenicity. Here, we describe the characterization of five undescribed mtDNA variants, upon detection of 23 unclassified alterations at Laboratory of Biochemical Genetics, from 2004 to 2014. Those five sequence variations are located in protein-coding genes, in five patients with a diverse range of mitochondrial respiratory chain disease phenotypes including encephalopathy, optic neuropathy, developmental delay, deafness and epilepsy. According to the prediction established by in silico analysis using tools to predict structure and function changes (ClustalW2®, PolyPhen-2®, SIFT®, MutationAssessor®, PredictProtein®, Provean®, I-TASSER®, Haplogrep®), from the 23 variants analyzed, the five described are potentially pathogenic. This approach is inexpensive and compatible with a rapid first line response to clinical demanding, contributing to a more rationale genetic diagnosis concerning novel mutations and to clarify the mtDNA involvement in these pathologies.

Evaluation of treatment with cysteamine eyedrops for cystinosis with confocal microscopy.

PURPOSE: The purpose of this study was to evaluate the efficacy of cysteamine eyedrops 0.1136% (new formulation, now stable at room temperature without the need for refrigeration for up to 2 months) for the treatment of cystine crystals in the cornea using slit lamp biomicroscopy and confocal microscopy. METHODS: A 20-year-old woman with infantile cystinosis, with a history of kidney transplantation at age 10, was studied. She applied cysteamine eyedrops (0.1136%) 10 times a day (a new formulation, now stable at room temperature without the need for refrigeration for up to 2 months, was prepared for compassionate use). The density of the cystine crystals in the cornea was evaluated using slit lamp biomicroscopy and confocal microscopy (Heidelberg Retina Tomograph 2 equipped with the Rostock Module for the Cornea). RESULTS: The deposits were absent in the surface epithelium and basal cells of the central cornea before and after treatment. We found crystals mainly in the anterior and medium stroma; they had various shapes; were intracellular, rectangular, or fusiform; and showed hyperreflectivity. The posterior stroma showed lower density of the crystals. No deposits in the endothelium were found. Therapy with cysteamine eyedrops reduced the density of the crystals and lessened the photophobia. CONCLUSION: Confocal microscopy is a valuable technique to study cystine crystals of the cornea in vivo. Cysteamine eyedrops appear to be very useful in the treatment of these crystals, especially for photophobic complaints.