Elena Procopio

GM1 gangliosidosis and Morquio B disease: an update on genetic alterations and clinical findings

GM1 gangliosidosis and Morquio B syndrome, both arising from beta-galactosidase (GLB1) deficiency, are very rare lysosomal storage diseases with an incidence of about 1:100,000-1:200,000 live births worldwide. Here we report the beta-galactosidase gene (GLB1) mutation analysis of 21 unrelated GM1 gangliosidosis patients, and of 4 Morquio B patients, of whom two are brothers. Clinical features of the patients were collected and compared with those in literature. In silico analyses were performed by standard alignments tools and by an improved version of GLB1 three-dimensional models. The analysed cohort includes remarkable cases. One patient with GM1 gangliosidosis had a triple X syndrome. One patient with juvenile GM1 gangliosidosis was homozygous for a mutation previously identified in Morquio type B. A patient with infantile GM1 gangliosidosis carried a complex GLB1 allele harbouring two genetic variants leading to p.R68W and p.R109W amino acid changes, in trans with the known p.R148C mutation. Molecular analysis showed 27 mutations, 9 of which are new: 5 missense, 3 microdeletions and a nonsense mutation. We also identified four new genetic variants with a predicted polymorphic nature that was further investigated by in silico analyses. Three-dimensional structural analysis of GLB1 homology models including the new missense mutations and the p.R68W and p.R109W amino acid changes showed that all the amino acid replacements affected the resulting protein structures in different ways, from changes in polarity to folding alterations. Genetic and clinical associations led us to undertake a critical review of the classifications of late-onset GM1 gangliosidosis and Morquio B disease.

Timed rise from floor as a predictor of disease progression in Duchenne muscular dystrophy: An observational study

Background The role of timed items, and more specifically, of the time to rise from the floor, has been reported as an early prognostic factor for disease progression and loss of ambulation. The aim of our study was to investigate the possible effect of the time to rise from the floor test on the changes observed on the 6MWT over 12 months in a cohort of ambulant Duchenne boys. Subjects and methods A total of 487 12-month data points were collected from 215 ambulant Duchenne boys. The age ranged between 5.0 and 20.0 years (mean 8.48 ±2.48 DS). Results The results of the time to rise from the floor at baseline ranged from 1.2 to 29.4 seconds in the boys who could perform the test. 49 patients were unable to perform the test at baseline and 87 at 12 month The 6MWT values ranged from 82 to 567 meters at baseline. 3 patients lost the ability to perform the 6mwt at 12 months. The correlation between time to rise from the floor and 6MWT at baseline was high (r = 0.6, p<0.01). Conclusions Both time to rise from the floor and baseline 6MWT were relevant for predicting 6MWT changes in the group above the age of 7 years, with no interaction between the two measures, as the impact of time to rise from the floor on 6MWT change was similar in the patients below and above 350 m. Our results suggest that, time to rise from the floor can be considered an additional important prognostic factor of 12 month changes on the 6MWT and, more generally, of disease progression.

Allergic bronchopulmonary aspergillosis in Italian cystic fibrosis patients: prevalence and percentage of positive tests in the employed diagnostic criteria.

The prevalence of allergic bronchopulmonary aspergillosis (ABPA) in cystic fibrosis (CF) patients is difficult to determine because the data in the literature are not homogeneous or comparable. ABPA and CF have similar clinical symptoms which make diagnosis difficult and underestimate the real dimensions of the problem. We conducted an epidemiological study on 3089 Italian CF patients to determine the prevalence of ABPA in Italy and verify the percentage of positive tests in the employed diagnostic criteria. Our results indicate that the prevalence of ABPA in Italian CF patients is 6.18%, mainly in adolescents and young adults. ABPA is diagnosed using clinical symptoms (presence of episodic bronchial obstructions or typical radiographic features) and on the basis of other criteria which can only be partially fulfilled in paediatric patients. Among the diagnostic tests the most sensitive are the total IgE (84.5%), specific IgE anti-Aspergillus fumigatus (81.6%) and the prick test (68.3%). In the absence of clinical symptoms and gold standard diagnostic tests, serological positivity and/or the skin test are not sufficient evidence to confirm the presence of ABPA.

Congenital disorders of glycosylation presenting as epileptic encephalopathy with migrating partial seizures in infancy

Epilepsy is commonly observed in congenital disorders of glycosylation (CDG), but no distinctive electroclinical pattern has been recognized. We aimed at identifying a characteristic clinical presentation that might help targeted diagnostic work‐up.

Optimizing the molecular diagnosis of GALNS: novel methods to define and characterize Morquio-A syndrome-associated mutations

Morquio A syndrome (MPS IVA) is a systemic lysosomal storage disorder caused by the deficiency of N‐acetylgalactosamine‐6‐sulfatase (GALNS), encoded by the GALNS gene. We studied 37 MPS IV A patients and defined genotype–phenotype correlations based on clinical data, biochemical assays, molecular analyses, and in silico structural analyses of associated mutations. We found that standard sequencing procedures, albeit identifying 14 novel small GALNS genetic lesions, failed to characterize the second disease‐causing mutation in the 16% of the patients’ cohort. To address this drawback and uncover potential gross GALNS rearrangements, we developed molecular procedures (CNV [copy‐number variation] assays, QF‐PCRs [quantitative fluorescent‐PCRs]), endorsed by CGH‐arrays. Using this approach, we characterized two new large deletions and their corresponding breakpoints. Both deletions were heterozygous and included the first exon of the PIEZO1 gene, which is associated with dehydrated hereditary stomatocitosis, an autosomal‐dominant syndrome. In addition, we characterized the new GALNS intronic lesion c.245‐11C>G causing m‐RNA defects, although identified outside the GT/AG splice pair. We estimated the occurrence of the disease in the Italian population to be approximately 1:300,000 live births and defined a molecular testing algorithm designed to help diagnosing MPS IVA and foreseeing disease progression.

Lesch-Nyhan syndrome presenting with acute renal failure in a 3-day-old newborn

Acute renal failure developed during the first 3 days after birth in a newborn subsequently diagnosed with hypoxanthine-guanine-phosphoribosyl-transferase (HPRT) deficiency. Fluid infusion and allopurinol therapy normalised renal function and serum uric acid levels. Only a few cases of acute renal failure due to acute hyperuricemic nephropathy related to HPRT deficiency have previously been reported in infants, and there are no reported cases in newborns as young as 3 days old.

Defective mitochondrial rRNA methyltransferase MRM2 causes MELAS-like clinical syndrome.

Abstract Defects in nuclear-encoded proteins of the mitochondrial translation machinery cause early-onset and tissue-specific deficiency of one or more OXPHOS complexes. Here, we report a 7-year-old Italian boy with childhood-onset rapidly progressive encephalomyopathy and stroke-like episodes. Multiple OXPHOS defects and decreased mtDNA copy number (40%) were detected in muscle homogenate. Clinical features combined with low level of plasma citrulline were highly suggestive of mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome, however, the common m.3243 A > G mutation was excluded. Targeted exome sequencing of genes encoding the mitochondrial proteome identified a damaging mutation, c.567 G > A, affecting a highly conserved amino acid residue (p.Gly189Arg) of the MRM2 protein. MRM2 has never before been linked to a human disease and encodes an enzyme responsible for 2’-O-methyl modification at position U1369 in the human mitochondrial 16S rRNA. We generated a knockout yeast model for the orthologous gene that showed a defect in respiration and the reduction of the 2’-O-methyl modification at the equivalent position (U2791) in the yeast mitochondrial 21S rRNA. Complementation with the mrm2 allele carrying the equivalent yeast mutation failed to rescue the respiratory phenotype, which was instead completely rescued by expressing the wild-type allele. Our findings establish that defective MRM2 causes a MELAS-like phenotype, and suggests the genetic screening of the MRM2 gene in patients with a m.3243 A > G negative MELAS-like presentation.

Recurrent drop attacks in early childhood as presenting symptom of benign hereditary chorea caused by TITF1 gene mutations.

Drop attacks are sudden, spontaneous falls without loss of consciousness, followed by rapid recovery. Causes in children include severe epilepsies, movement disorders, cataplexy, and psychiatric disorders. We describe two children (a 3‐year‐old female and a 12‐year‐old male) with mild neuromotor delay and sudden falls appearing upon starting to walk. Extensive clinical and laboratory investigation was unremarkable. Twenty to 22 months after the onset of falls, both children developed subtle choreiform movements, affecting all four limbs, leading to frequent falls, at times causing traumatic injury. A heterozygous mutation of the TITF1/NKX2‐1 gene (14q13) was detected in both patients, allowing the diagnosis of benign hereditary chorea (BHC). Treatment with levodopa attenuated abnormal movements and led to disappearance of drop attacks. A diagnosis of BHC should be considered in young children with recurrent and unexplained drop attacks, especially if associated with neuromotor delay, even in the absence of choreiform movements.

Neuroimaging changes in menkes disease, part 1

SUMMARY: Menkes disease is a rare multisystem X-linked disorder of copper metabolism. Despite an early, severe, and progressive neurologic involvement, our knowledge of brain involvement remains unsatisfactory. The first part of this retrospective and review MR imaging study aims to define the frequency rate, timing, imaging features, and evolution of intracranial vascular and white matter changes. According to our analysis, striking but also poorly evolutive vascular abnormalities characterize the very early phases of disease. After the first months, myelination delay becomes evident, often in association with protean focal white matter lesions, some of which reveal an age-specific brain vulnerability. In later phases of the disease, concomitant progressive neurodegeneration might hinder the myelination progression. The currently enriched knowledge of neuroradiologic finding evolution provides valuable clues for early diagnosis, identifies possible MR imaging biomarkers of new treatment efficacy, and improves our comprehension of possible mechanisms of brain injury in Menkes disease.

Clinical features and outcome of 6 new patients carrying de novo KCNB1 gene mutations

Objective: To describe electroclinical features and outcome of 6 patients harboring KCNB1 mutations. Methods: Clinical, EEG, neuropsychological, and brain MRI data analysis. Targeted next-generation sequencing of a 95 epilepsy gene panel. Results: The mean age at seizure onset was 11 months. The mean follow-up of 11.3 years documented that 4 patients following an infantile phase of frequent seizures became seizure free; the mean age at seizure offset was 4.25 years. Epilepsy phenotypes comprised West syndrome in 2 patients, infantile-onset unspecified generalized epilepsy, myoclonic and photosensitive eyelid myoclonia epilepsy resembling Jeavons syndrome, Lennox-Gastaut syndrome, and focal epilepsy with prolonged occipital or clonic seizures in each and every one. Five patients had developmental delay prior to seizure onset evolving into severe intellectual disability with absent speech and autistic traits in one and stereotypic hand movements with impulse control disorder in another. The patient with Jeavons syndrome evolved into moderate intellectual disability. Mutations were de novo, 4 missense and 2 nonsense, 5 were novel, and 1 resulted from somatic mosaicism. Conclusions: KCNB1-related manifestations include a spectrum of infantile-onset generalized or focal seizures whose combination leads to early infantile epileptic encephalopathy including West, Lennox-Gastaut, and Jeavons syndromes. Long-term follow-up highlights that following a stormy phase, seizures subside or cease and treatment may be eased or withdrawn. Cognitive and motor functions are almost always delayed prior to seizure onset and evolve into severe, persistent impairment. Thus, KCNB1 mutations are associated with diffuse brain dysfunction combining seizures, motor, and cognitive impairment.