👤 A Simonati

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare inherited white matter disorder. Initially, a "classic" phenotype has been characterized, presenting early-onset macrocephaly, cerebellar ataxia, mild spasticity, and a distinctive neuroimaging pattern of diffuse white matter abnormalities with subcortical cysts. An "improving" phenotype has also been described, featuring milder or absent neurological signs and a remitting pattern on neuroimaging. Mutations in four genes, MLC1, HEPACAM, GPRC5B and AQP4 have been associated with MLC. We describe clinical and genetic features of a cohort of genetically confirmed Italian MLC patients, representing the largest Italian cohort reported to date. We conducted a retrospective, multicenter, observational study. Patients were included based on clinical and neuroimaging features consistent with MLC, along with a confirmed genetic diagnosis. Data were collected using a standardized database and included demographic, clinical, neuroimaging, neurophysiological, and genetic information. Thirty-three patients from eight Italian centers were enrolled. Twenty-seven harbored biallelic MLC1 variants (23 distinct mutations, including three novel variants), while six had three distinct heterozygous HEPACAM variants. All MLC1-mutated patients exhibited the "classic" phenotype, frequently accompanied by orthopedic, gastrointestinal, and respiratory comorbidities. HEPACAM-mutated patients were consistent with the "improving" phenotype. No patients harbored mutations in GPRC5B or AQP4. Our findings expand the mutational spectrum of MLC1, further characterize the disease phenotype, and provide valuable insights into its presence in Italy. They also underscore management needs of individuals with MLC, highlighting the importance of multidisciplinary care. Show less

• Neuronal Ceroido Lipofuscinoses (NCL) are inherited, neurodegenerative disorders associated with lysosomal storage. • Impaired autophagy plays a pathogenetic role in several NCL forms, including CLN3 disease, but study on human brains are lacking. • In post-mortem brain samples of a CLN3 patient the LC3-I to LC3-II shift was consistent with activated autophagy. However, the autophagic process seemed to be ineffective due to the presence of lysosomal storage markers. • After fractionation with buffers of increasing detergent-denaturing strength, a peculiar solubility pattern of LC3-II was observed in CLN3 patient's samples, suggesting a different lipid composition of the membranes where LC3-II is stacked. Show less

In childhood the neuronal ceroid lipofuscinoses (NCL) are the most frequent lysosomal diseases and the most frequent neurodegenerative diseases but, in adulthood, they represent a small fraction among the neurodegenerative diseases. Their morphology is marked by: (i) loss of neurons, foremost in the cerebral and cerebellar cortices resulting in cerebral and cerebellar atrophy; (ii) an almost ubiquitous accumulation of lipopigments in nerve cells, but also in extracerebral tissues. Loss of cortical neurons is selective, indiscriminate depletion in early childhood forms occurring only at an advanced stage, whereas loss of neurons in subcortical grey-matter regions has not been quantitatively documented. Among the fourteen different forms of NCL described to date, CLN1 and CLN10 are marked by granular lipopigments, CLN2 by curvilinear profiles (CVPs), CLN3 by fingerprint profiles (FPPs), and other forms by a combination of these features. Among extracerebral tissues, lymphocytes, skin, rectum, skeletal muscle and, occasionally, conjunctiva are possible guiding targets for diagnostic identification, the precise type of NCL then requiring molecular analysis within the clinical and morphological context. Autosomal-recessive adult NCL has been linked molecularly to different childhood forms, i.e. CLN1, CLN5, and CLN6, whilst autosomal-dominant adult NCL, now designated as CLN4, is caused by a newly identified separate gene, DNAJC5. This article is part of a Special Issue entitled: The Neuronal Ceroid Lipofuscinoses or Batten Disease. Show less

Clinical findings and pathological features of 28 patients affected with neuronal ceroid lipofuscinoses (NCL) are reviewed. The patient group included 15 children affected with the late-infantile form of NCL (LINCL), 10 patients affected with the juvenile form (JNCL), and 3 adult cases. Ultrastructural examinations of 50 biopsies from 6 tissues were consistent with clinical features in all LINCL and JNCL cases but one. The importance of electron microscopic (EM) examination of blood lymphocytes in these forms is outlined, particularly when combined with molecular analysis of the CLN2 or CLN3 genes, respectively. This approach leads to a definite diagnosis of LINCL and JNCL in a relatively short time. In adult NCL, diagnosis still relies on pathological grounds, and difficulties in interpreting the osmiophilic storage bodies in different tissues are outlined. EM investigation of blood lymphocytes was not helpful in any case of adult NCL. Results of one stereotactic brain biopsy are also reported. Show less