Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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 CLN1to 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.
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PMID:Pheno/genotypic correlations of neuronal ceroid lipofuscinoses. 1154 35

Mutations in palmitoyl protein thioesterase-1 (PPT1) have been found to cause the infantile form of neuronal ceroid lipofuscinosis, which is a lysosomal storage disorder characterized by impaired degradation of fatty acid-modified proteins with accumulation of amorphous granular deposits in cortical neurons, leading to mental retardation and death. Palmitoyl protein thioesterase-2 (PPT2) is a second lysosomal hydrolase that shares a 26% identity with PPT1. A previous study had suggested that palmitoyl-CoA was the preferred substrate of PPT2. Furthermore, PPT2 did not hydrolyze palmitate from the several S-palmitoylated protein substrates. Interestingly, PPT2 deficiency in a recent transgenic mouse model is associated with a form of neuronal ceroid lipofuscinosis, suggesting that PPT1 and -2 perform non-redundant roles in lysosomal thioester catabolism. In the current paper, we present the crystal structure of PPT2 at a resolution of 2.7 A. Comparisons of the structures of PPT1 and -2 show very similar architectural features; however, conformational differences in helix alpha4 lead to a solvent-exposed lipid-binding groove in PPT1. The limited space between two parallel loops (beta3-alphaA and beta8-alphaF) located immediately above the lipid-binding groove in PPT2 restricts the binding of fatty acids with bulky head groups, and this binding groove is significantly larger in PPT1. This structural difference accounts for the ability of PPT2 to hydrolyze an unbranched structure such as palmitoyl-CoA but not palmitoylcysteine or palmitoylated proteins. Furthermore, differences in fatty acid chain length specificity of PPT1 and -2, also reported here, are explained by the structure and may provide a biochemical basis for their non-redundant roles.
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PMID:The crystal structure of palmitoyl protein thioesterase-2 (PPT2) reveals the basis for divergent substrate specificities of the two lysosomal thioesterases, PPT1 and PPT2. 1285 96

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.
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PMID:Current state of clinical and morphological features in human NCL. 1499 38