A form of juvenile Batten disease with granular osmiophilic deposits

The neuronal ceroid-lipofuscinoses. Recent advances

The neuronal ceroid lipofuscinoses (NCLs) represent a group of neurodegenerative disorders characterised by progressive visual failure, neurodegeneration, epilepsy and the accumulation of an autofluorescent lipopigment in neurons and other cells. The main childhood subtypes are infantile (INCL;CLN1), classical late infantile (LINCL;CLN2) and juvenile NCL (JNCL;CLN3), distinguished on the basis of age of onset, clinical course and ultrastructural morphology, and recently genetic analysis. In addition several variant forms of the disease complex have been described as well as a rare adult onset form. Advances in both genetics and biochemistry have led to the identification of the genes for the three main subtypes of childhood NCL and their corresponding protein products and to mapping of two additional genes for two variant forms. The disease causing genes in both INCL and classical LINCL have been shown to encode lysosomal enzymes whilst the JNCL gene codes for a protein whose function is as yet unknown.

Extracerebral biopsy in lysosomal and peroxisomal disorders. Ultrastructural findings

The lysosomal and peroxisomal disorders are characterized by specific storage affecting mainly the central nervous system with involvement of the peripheral nervous system and visceral organs. Most of these disorders can now be diagnosed by using biochemical and enzymatical assays and by molecular biology techniques, without the need for a brain biopsy used previously. Extraneural tissue biopsies have also been investigated at the ultrastructural level. The study of such tissues is still necessary when the enzymatic or biochemical defect remains unknown and when DNA studies are not informative. The choice of tissue is important. Skin and conjunctival biopsies are less traumatic and are cost-effective diagnostic tools allowing the examination of a great diversity of structures. Skeletal muscle and peripheral nerves are more frequently used for patients with a late-onset or slower course of disease. Rectal biopsy is helpful when neurons require examination in lysosomal diseases, whereas liver is more usually investigated than adrenal or testis in peroxisomal diseases. Bone marrow is most useful for Gaucher's disease while lymphocytes may be examined for all lysosomal disorders as a first diagnostic approach. Chorionic villi still have a diagnostic role in combination of electron microscopy with DNA studies in early pregnancies at-risk for neuronal ceroid lipofuscinosis. Cultured fibroblasts are less informative than other biopsy samples for the morphological evaluation of lysosomal and peroxisomal disorders.

Impaired cell adhesion and apoptosis in a novel CLN9 Batten disease variant

We describe the ninth variant of neuronal ceroid lipofuscinosis (NCL) or Batten disease, due to defects in a putative new gene, CLN9. We therefore refer to the new variant as CLN9-deficient. Two Serbian sisters and two German brothers are described. Their clinical history is characteristic for juvenile NCL. They show similar gene expression patterns. The existence of this variant is supported by the presence of curvilinear inclusions, fingerprint profiles, and granular osmiophilic deposits in neurons, lymphocytes, and conjunctival cells. Enzyme screening and sequencing of the coding regions of other NCL genes was negative. CLN9-deficient cells have a distinctive phenotype. They have rounded cell bodies, have prominent nucleoli, attach poorly to the culture dish, and are sensitive to apoptosis but have increased growth rates. Gene expression of proteins involved in cell adhesion and apoptosis is altered in these cells. Sphingolipid metabolism is also perturbed. They have decreased levels of ceramide, sphingomyelin, lactosylceramide, ceramide trihexoside, and globoside and increased activity of serine palmitoyl transferase.

Current state of clinical and morphological features in human NCL

The neuronal ceroid lipofuscinoses (NCL) are a large group of autosomal recessive lysosomal storage disorders with both enzymatic deficiency and structural protein dysfunction. Previously, diagnosis of NCL was based on age at onset and clinicopathological (C-P) findings described 4 forms, classified as infantile (INCL) (2), late-infantile (LINCL) (5), juvenile (JNCL) (6), and adult (ANCL) (12). Most patients with NCL have progressive ocular and cerebral dysfunction, including cognitive/motor dysfunction and uncontrolled seizures. After reviewing 520 patients with NCL, we found that about 104 (20%) did not fit this classification of NCL. With further research, 4 additional forms have been recognized: Finnish (13), Gypsy/Indian (14), Turkish (15)--variants of LINCL, and Northern epilepsy (16), also known as progressive epilepsy with mental retardation. These eight NCL forms resulted from 151 different mutations in genes CLN1 to CLN8 causing different phenotypes (http://www.ucl.ac.uk/ncl). The genes CLN1 and CLN2 encode lysosomal palmitoyl protein thioesterase and tripeptidyl peptidase 1. The diagnosis of NCL is based on clinicopathological (C-P) findings, enzymatic assay, and molecular genetic testing. Ultrastructural studies must be performed to confirm the presence and nature of lysosomal storage material (fingerprint or curvilinear profiles, or granular osmiophilic deposits) before doing biochemical testing. Pheno/genotypic correlation studies are discussed.

Neuronal ceroid lipofuscinoses: classification and diagnosis

The neuronal ceroid lipofuscinoses (NCLs) are neurodegenerative disorders characterized by accumulation of ceroid lipopigment in lysosomes in various tissues and organs. The childhood forms of the NCLs represent the most common neurogenetic disorders of childhood and are inherited in an autosomal-recessive mode. The adult form of NCL is rare and shows either an autosomal-recessive or autosomal dominant mode of inheritance. Currently, five genes associated with various childhood forms of NCLs, designated CLN1, CLN2, CLN3, CLN5, and CLN8, have been isolated and characterized. Two of these genes, CLN1 and CLN2, encode lysosomal enzymes: palmitoyl protein thioesterase 1 (PPT1) and tripetidyl peptidase 1 (TPP1), respectively. CLN3, CLN5, and CLN8 encode proteins of predicted transmembrane topology, whose function has not been characterized yet. Two other genes, CLN6 and CLN7, have been assigned recently to small chromosomal regions. Gene(s) associated with the adult form of NCLs (CLN4) are at present unknown. This study summarizes the current classification and new diagnostic criteria of NCLs based on clinicopathological, biochemical, and molecular genetic data. Material includes 159 probands with NCL (37 CLNI, 72 classical CLN2, 10 variant LINCL, and 40 CLN3) collected at the New York State Institute for Basic Research in Developmental Disabilities (IBR) as well as a comprehensive review of the literature. The results of our study indicate that although only biochemical and molecular genetic studies allow for definitive diagnosis, ultrastructural studies of the biopsy material are still very useful. Thus, although treatments for NCLs are not available at present, the diagnosis has become better defined.

Clinical and neuroradiological diagnostic aspects of neuronal ceroid lipofuscinoses disorders

Early diagnosis is mandatory for avoiding further cases in families with hereditary metabolic brain disorders. This review lists the most important clinical symptoms and neuroradiological findings at the early stage of the seven most common childhood neuronal ceroid lipofuscinoses (NCL) types. In the infantile type the typical magnetic resonance imaging (MRI) findings can be seen even before the clinical signs. In the classic late infantile type (CLN2), MRI is less informative but in this and in the variant late infantile type CLN6 the characteristic neurophysiological findings are present at an early stage, although not in the Finnish variant CLN5. In the latter, the clinical diagnosis depends on ophthalmological and MRI findings. The combination of ophthalmological deficits and vacuolated lymphocytes is highly characteristic of the juvenile type (CLN3). A new NCL type, Northern epilepsy (CLN8), is also briefly reviewed.

Neuronal ceroid lipofuscinoses: a review

Neuronal ceroid lipofuscinoses (NCLs) are among the most common neurodegenerative diseases in childhood but rarely present in adulthood. The main symptoms are psychomotor deterioration, visual failure, epilepsy and motor disturbances. The NCLs are morphologically characterized by the accumulation of lipopigments within numerous cell types and loss of neurons. Pathogenesis is unknown. The current clinical classification recognizes six classic types of NCL and several atypical forms. Electrophysiological and neuroradiological findings may be of diagnostic significance, but disease recognition rests on the demonstration of a typical ultrastructural pattern. Genetic studies have demonstrated that several different genetic loci are involved in the pathogenesis of NCL, but the molecular mechanisms underlying neuronal death and lipopigment accumulation are not understood.