Variant late infantile ceroid lipofuscinoses associated with novel mutations in CLN6 Natalia Cannelli a,1 , Barbara Garavaglia b,1 , Alessandro Simonati c , Chiara Aiello a , Chiara Barzaghi b , Francesco Pezzini c , Maria Roberta Cilio a , Roberta Biancheri d , Michela Morbin b , Bernardo Dalla Bernardina c , Tiziana Granata b , Alessandra Tessa a , Federica Invernizzi b , Alice Pessagno d , Renata Boldrini a , Federica Zibordi b , Luisa Grazian e , Dianela Claps a , Rosalba Carrozzo a , Sara E. Mole f , Nardo Nardocci b , Filippo M. Santorelli a, * a Molecular Medicine, Neurology, and Pathology, IRCCS-Bambino Gesù Hospital, Piazza S. Onofrio 4, 00165 Rome, Italy b Neuropediatrics, Neurogenetics, and Neuropathology, IRCCS C. Besta Neurological Institute Foundation, Milan, Italy c Department Neurological and Visual Sciences-Neurology, and Mother, Child and Biology-Child Neurology and Psychiatry, University of Verona Medical School, Verona, Italy d Child Neuropsychiatry, IRCCS-G.Gaslini Institute, Genova, Italy e Pediatric Unit, Ca’ Foncello Hospital, Treviso, Italy f MRC Laboratory for Molecular Cell Biology, Molecular Medicine Unit, UCL Institute of Child Health, and Department of Genetics, Evolution and Environment, University College London, UK article info Article history: Received 21 December 2008 Available online 7 January 2009 Keywords: v-LINCL CLN6 Autophagy Mutation scanning abstract The neuronal ceroid lipofuscinoses (NCL) are heterogeneous neurodegenerative disorders with typical autofluorescence material stored in tissues. Ten clinical NCL forms and eight causative genes are known. Mutations in CLN6 have been reported in roughly 30 patients, mostly in association with the variant late- infantile NCL (v-LINCL) phenotype. We screened CLN6 in 30 children from a cohort of 53 v-LINCL cases and revised their clinical and ultrastructural features. We detected 11 mutations, eight of which are novel, all predicting a direct impairing of the putative gene function. No clear-cut genotype–phenotype correlations were observed, with inter- and intra-familial variability evident for few recurrent mutations. Ultrastructural findings were suggestive of an impaired regulation of the autophagic vacuoles turnover. While expanding the array of CLN6 mutations, we showed that more than half of our v-LINCL cases lack a DNA confirmation and further molecular etiologies are to be searched. Ó 2008 Elsevier Inc. All rights reserved. The neuronal ceroid lipofuscinoses (NCL) are a mixed group of progressive disorders of the brain and eyes characterized by the accumulation of autofluorescence storage material in tissues, espe- cially in neurons [1]. The overall incidence of NCL in Europe, North America, and some other countries can be as high as 1 in 12,500, with a high carrier frequency in Finland [2]. Clinical manifestations usually begin during childhood and adolescence, but rare cases of onset in adults and also around birth have been reported. These heterogeneous disorders share similar symptoms and signs, such as retinopathy with loss of vision, epilepsy, dementia, and accumu- lation of unusual waxy material termed ceroid lipofuscin (autoflu- orescent lipopigments) in brain and other tissues [1]. The mode of transmission is mostly autosomal recessive. Their pathophysiology is poorly understood and involves the combination of an intracel- lular storage process and a progressive loss of nerve cells. All NCL disorders remain untreatable, progress relentlessly, and usually lead to early death [2]. On the basis of age of onset, geographical origin and molecular defects, 10 forms can be identified, with eight genes (CTSD/CLN10, CLN1, CLN2, CLN3, CLN5, CLN6, MFSD8/CLN7, and CLN8) known; hence further heterogeneity is anticipated [3]. In the pregenetic era, NCL were considered extremely rare in Italy [4], but subse- quent studies recognized the presence of variant late-infantile (v- LINCL) clinical forms with a later age of onset and distinct clinical and histological phenotypes. Molecular analyses sustained genetic heterogeneity in v-LINCL, with the identification of mutations in CLN5 [5], CLN8 [6], and more recently CLN7 [7]. The CLN6 gene lies on chromosome 15q22–23 [8] and encodes a 311 amino acid protein with seven predicted transmembrane do- mains. The deduced amino acid sequence does not contain classical lysosomal sorting signals, and the CLN6 protein was shown to re- side in the endoplasmic reticulum (ER) [9,10]. Thirty different mutations have been reported—the most frequent being the c.214G > T (p.Glu72Stop), followed by the c.460_462delATC variant 0006-291X/$ - see front matter Ó 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.bbrc.2008.12.159 * Corresponding author. Fax: +39 0668592024. E-mail address: filippo3364@gmail.com (F.M. Santorelli). 1 These authors equally contributed to this work. Biochemical and Biophysical Research Communications 379 (2009) 892–897 Contents lists available at ScienceDirect Biochemical and Biophysical Research Communications journal homepage: www.elsevier.com/locate/ybbrc