A case of "atypical" Down Syndrome (DS), where the proposita did not exhibit all of the clinical features of DS and had de novo partial trisomy 21, was studied. Results from phenotypic, chromosome banding and superoxide dismutase (SOD) gene dosage studies suggest a karyotype of 46,XX,-12,+t(12pter to 12qter::21q21 to 21q22.?2). Additional studies of such atypical cases will provide more precise sublocalization for both gene and phenotypic mapping of the bands that are responsible for the DS phenotype.

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.

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 clinicopathologic (C-P) findings, classified as 1) infantile (INCL), 2) late infantile (LINCL), 3) juvenile (JNCL), and 4) adult (ANCL). Most patients with NCL have progressive ocular and cerebral dysfunction, including cognitive/motor dysfunction and uncontrolled seizures. After reviewing 319 patients with NCL, the authors found that 64 (20%) did not fit into this classification of NCL. With research progress, four additional forms have been recognized: 5) Finnish, 6) Gypsy/Indian, and 7) Turkish variants of LINCL and 8) northern epilepsy, also known as progressive epilepsy with mental retardation. These eight NCL forms resulted from 100 different mutations on 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 function of CLN3, CLN5, and CLN8 gene-encoded products is unknown, although their predicted amino acid sequences suggest they have a transmembrane topology. The diagnosis of NCL is based on C-P findings, enzymatic assay, and molecular genetic testing. Before biochemical and genetic tests are conducted, ultrastructural studies (i.e., blood [buffy coat] or punch biopsies [skin, conjunctiva]) must be performed to confirm the presence and nature of lysosomal storage material (fingerprint or curvilinear profiles or granular osmiophilic deposits). The recognition of variable onset from infancy to middle age supersedes the traditional emphasis on age-related NCL forms.

A 5-year-old boy presented with frequent absences. Speech began to regress. He became ataxic, barely able to walk. Studies with Xe-133 and hexamethylpropylene amine oxime single-photon emission computed tomography revealed sharply decreased cerebral blood flow, especially in the occipital area. Landau-Kleffner syndrome was suspected but a sleep electroencephalogram showed few abnormalities. He was started on clorazepate and diltiazem. A skin biopsy to rule out possible CLN2 revealed, instead of the predicted curvilinear profiles, granular osmiophilic deposits, consistent with infantile neuronal ceroid lipofuscinosis (CLN1). The family reported increased seizure frequency and consulted with a colleague, who advised them to resume valproate and discontinue diltiazem. The boy died shortly thereafter. Decreased cerebral blood flow is a new finding in CLN1 with delayed onset. Calcium-channel blockers improve cerebral blood flow and perhaps delay clinical regression.

This study describes the phenotype/genotype analysis of 159 probands with neuronal ceroid lipofuscinosis (37 CLN1, 72 classic CLN2, 10 variant LINCL, and 40 CLN3) collected at the New York State Institute for Basic Research in Developmental Disabilities (IBR). Phenotype/genotype comparison showed that mutations in the CLN1 gene were associated with different phenotypes: infantile, late infantile, and juvenile. Two common mutations (223A → C and 451C → T) were found in 26 of 37 CLN1 subjects (64% of alleles examined). A nonsense point mutation, 451C → T, was the most common in CLN1 subjects with infantile onset at 0–2 years, accounting for 50% of alleles studied. A missense point mutation, 223A → C, was the most common among CLN1 subjects with juvenile onset older than 4 years, accounting for 45% of alleles examined. Twenty-one other CLN1 mutations were identified in 4 of 37 subjects with infantile onset, 6 of 37 with late-infantile onset, and 6 of 37 with juvenile onset. All CLN1 probands were palmitoyl-protein thioesterase (PPT)-deficient and showed granular osmiophilic deposits (GROD) at the electron microscopic (EM) level. In the group of classic CLN2 (72 probands), two common mutations were found; an intronic 3556G → C transversion in the invariant AG of 3’ splice junction in 55% of probands, and a nonsense mutation 3670C → T in 30% of probands. Classic late-infantile onset (2–4 years) was found in 68 of 72 (95%) cases. All probands had deficiency of tripeptidyl-peptidase I (TPP1) activity and, at the EM level, curvilinear profiles. Ten probands with late-infantil onset did not show mutations in the CLN2 gene, had normal TPP1 activity, and at the EM level had mixed profiles. Further studies are in progress to identify genetic defect(s) in these subjects. The CLN3 group (40 probands) was divided into two categories: classic or typical presentation, and delayed classic or atypical presentation. All CLN3 patients had onset of symptoms after 4 years of age. In 40 probands, the 1.02-kb common deletion was found in one or two alleles of the CLN3 gene. Homozygotes for the common CLN3 deletion showed the classic phenotype. The phenotype in compound heterozygotes was either the classic or the delayed classic or atypical form. Thus, our study indicates that some mutations in the CLN1 and CLN2 genes may be associated with juvenile onset of the disease process and a more benign clinical course. Interfamilial and intrafamilial variations also were found, especially in the speed of becoming blind and neurologically disabled.

Eight unrelated children with progressive neurological deterioration and granular osmiophilic deposits (GROD) due to an underlying palmitoyl-protein thioesterase deficiency were analyzed for mutations in the PPT1 gene. Three novel mutations (G118D, Q291X and F84del) were identified. The novel Q291X mutation was observed in an African-American child. The G118D and Q291X mutations occurred in infantile-onset subjects. These two mutations would be predicted to have severe effects on enzyme activity. The novel F84del mutation involves an invariant phenylalanine residue. A missense mutation, Q177E, occurred in three subjects from two families with late-infantile NCL, confirming an association of the Q177E mutation with a late-infantile phenotype. Other previously described mutations were R151X (5/16 alleles), T75P (3/16 alleles), R164X (1/16 alleles), and V181M (1/16 alleles). The current study expands the spectrum of mutations in PPT1 deficiency and further confirms the broad range of age of onset of symptoms resulting from an enzyme deficiency previously associated only with infantile NCL.

The lysosomal storage of lipofuscins is the common pathological feature that characterizes the infantile, late-infantile, juvenile (Batten's disease), and Finnish-variant neuronal ceroid lipofuscinosis (INCL, LINCL, JNCL and FNCL), which are due to mutations in the genes CLN1, CLN2, CLN3, and CLN5, respectively. The CLN1 and CLN2 genes encode lysosomal enzymes, but the CLN3 and CLN5 genes encode membrane-spanning proteins. Why deficiencies of lysosomal enzymes and membrane-spanning proteins produce similar clinical phenotypes and pathological changes is still unanswered. We hypothesize that CLN-encoded proteins may comprise a functional pathogenic pathway, in which protein associations may play important roles. To test this hypothesis, we studied protein-protein interactions among the CLN1-, CLN2-, and CLN3-encoded proteins using a yeast two-hybrid system. Our results provided no evidence that CLN-encoded proteins interact with each other. This suggests there may be unidentified components in NCL pathogenesis.

Neuronal ceroid lipofuscinoses (NCLs) are a group of genetically transmitted neurodegenerative disorders characterized clinically by intellectual and motor decline, visual loss, and myoclonic seizures, in most cases preceded by a variable period of apparently normal development. A common pathological feature of all NCLs is the intracellular accumulation of an autofluorescent material resembling ceroid or lipofuscin. Five genes ( CLN1 , CLN2 , CLN3 , CLN5 , and CLN8 ) have been identified that are mutated in different forms of NCL: respectively, infantile NCL (1); late infantile NCL (2)(3); classical juvenile NCL (4)(5)(6); Finnish variant late infantile NCL (7); and the progressive epilepsy with mental retardation (EPMR, also called Northern epilepsy) (8). Adult-onset NCL (CLN4) follows either an autosomal recessive (Kufs disease) or an autosomal dominant (Parry disease) pattern of inheritance and is likely to be linked to different, as yet unknown, gene loci. The classical late infantile and juvenile forms, by far the commonest NCLs reported in different populations, are leading causes of neurodegeneration in childhood and adolescence. More than 30 mutations, scattered along the whole CLN2 gene, have been reported in association with the classical late infantile NCL (cLINCL) phenotype (9)(10). However, studies performed on large groups of cLINCL patients demonstrated that two mutations, 636C→T and T523-1G→C, are particularly common (9)(11). They occur in ∼60% of cLINCL chromosomes, and at least one of these mutations can be identified in >75% of patients (12). We report here (a) successful development of a real-time multiplex fluorescence PCR with two dyes for the rapid detection of these two mutations and (b) genetic analysis of five new cLINCL families from South-Eastern Poland. We obtained DNA samples for genotyping from five previously unreported cLINCL families with 5 cLINCL patients and 18 healthy relatives. Family members gave …

Expression of the gene for Batten disease (CLN3) was studied in Escherichia coli and in a cell-free rabbit reticulocyte expression systems. A full-length recombinant fusion CLN3 protein was not produced in the bacterial systems used. However, both N-terminal fragment encompassing 246 amino acids and short C-terminal fragment containing 428-438 amino acids of the CLN3 protein were successfully overexpressed in bacteria. Further studies showed that the C-terminal sequence of the CLN3 protein corresponding to the 356-438 amino acid residues was responsible for inhibition of protein synthesis in bacteria. The full-length CLN3 gene product was readily synthesized in vitro in the cell-free rabbit reticulocyte expression system. The product obtained, corresponding to core CLN3 protein, showed an approximate molecular weight of 43 kDa. Immunoprecipitation of this product with pAb to 4-19 amino acids of the CLN3 protein allows us to suggest that CLN3 protein translation starts at Met-1.

Although the molecular basis of programmed cell death, a pivotal process for the proper development, organization and future functioning of the brain, has been studied extensively in different experimental models and in various species, it is not entirely understood. The principles that govern this process in the developing human brain are even less elucidated. To provide more insight into the mechanisms underlying programmed cell death in the human brain, we have studied the temporal and spatial pattern of immunolocalization in the developing normal and Down syndrome brain of two proteins that are supposed to act either as a neuronal survival promoter-Bcl-2 or a neuronal survival suppressor- Bax. Our data show a dramatic decrease in immunoreactivity to Bcl-2 and, at the same time, a gradual increase in immunoreactivity to Bax in the human brain around 30-32 week’s gestation; according to recent data, this gestational period is accompanied by the most intense reduction of cortical neurons. However, our obser vations also suggest that at least at certain stages of human brain development, both proteins, and especially Bax, may also be involved in the final differentiation and maturation of central nervous system neurons. In addition, altered patterns of Bcl-2 and, to a much lesser degree, also of Bax immunoreactivity in developing Down syndrome brain allow us to propose that mechanisms underlying programmed cell death may contribute to the pathology in Down syndrome brain.

Studying peripheral blood mononuclear cells (PBMCs) has become an important diagnostic tool in lysosomal storage diseases. Previous studies revealed that B and subclasses of T lymphocytes participate in the storage process, whereas the role of circulating monocytes was not clear. In this study, the involvement of CD14+ monocytes in lysosomal diseases was investigated. Blood samples from six patients with different lysosomal storage disorders were studied, including one with late--infantile and three with juvenile neuronal ceroid--lipofuscinoses, and two with mucopolysaccharidosis type VI. CD14+ cells were separated immunomagnetically from PBMCs and studied by light and electron microscopy. In all investigated disorders, disease-specific lysosomal storage material could be found in monocytes. The ratio of affected to non-affected cells did not differ from previously reported data on lymphocytes and their subforms in these diseases. Our data were obtained by studying a small number of different lysosomal storage disorders. Nevertheless, they suggest that lysosomal storage in the monocyte-macrophage system might also be found in other forms of lysosomal diseases.

The novel lipid second messenger, ceramide, induced apoptosis in PC12 cells as determined morphologically by nuclear appearance and internucleosomal DNA fragmentation. Apoptosis was induced by exogenous C2-ceramide in a dose- and time-dependent manner. Natural ceramide and C6-ceramide had a similar effect. This response was specific since the structural analog C2-dihydroceramide and other related lipids failed to initiate apoptosis. The apoptotic effect of ceramide also depends critically on cell plating density. Furthermore, the peptide inhibitor of interleukin-1β converting enzyme (ICE)-like proteases, Z-VAD.FMK, completely prevented the nuclear changes induced by ceramide, implicating the involvement of ICE-like protease activation in ceramide-induced apoptosis in PC12 cells.