Neuronal ceroid lipofuscinosis type CLN2: A new rationale for the construction of phenotypic subgroups based on a survey of 25 cases in South America
Tripeptidyl-peptidase 1 (TPP1) null or residual activity occurs in neuronal ceroid lipofuscinosis (NCL) with underlying TPP1/CLN2 mutations. A survey of 25 South American CLN2 affected individuals enabled the differentiation of two phenotypes: classical late-infantile and variant juvenile, each in a...
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Published in | Gene Vol. 516; no. 1; pp. 114 - 121 |
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Main Authors | , , , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Netherlands
Elsevier B.V
01.03.2013
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Subjects | |
Online Access | Get full text |
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Summary: | Tripeptidyl-peptidase 1 (TPP1) null or residual activity occurs in neuronal ceroid lipofuscinosis (NCL) with underlying TPP1/CLN2 mutations. A survey of 25 South American CLN2 affected individuals enabled the differentiation of two phenotypes: classical late-infantile and variant juvenile, each in approximately 50% of patients, with residual TPP1 activity occurring in approximately 32%. Each individual was assigned to one of three subgroups: (I) n=11, null TPP1 activity in leukocytes; (II) n=8, residual TPP1 activity of 0.60–15.85nmol/h/mg (nr 110–476); (III) n=6, activity not measured in leukocytes. Curvilinear bodies (CB) appeared in almost all studied CLN2 subjects; the only exceptions occurred in cases of subgroup II: two individuals had combined CBs/fingerprints (FPs), and one case had pure FPs. There were 15 mutations (4 first published in this paper, 3 previously observed in South America by our group, and 8 previously observed by others). In subgroup I, mutations were either missense or nonsense; in subgroups II and III, mutations prevailed at the non-conserved intronic site, c.887−10A>G (intron 7), and to a lesser extent at c.89+5G>C (intron 2), in heterozygous combinations. Grouping phenotypically and genetically known individuals on the basis of TPP1 activity supported the concept that residual enzyme activity underlies a protracted disease course. The prevalence of intronic mutations at non-conserved sites in subgroup II individuals indicates that some alternative splicing might allow some residual TPP1 activity.
► CLN2 is the most frequent neuronal ceroid lipofuscinosis in South America. ► Two CLN2 groups have been recognized: I-null TPP1 activity; II-residual TPP1 activity. ► The variant juvenile phenotype comprises approximately 50% of CLN2 in South America. ► Slight residual TPP1 activity had an effect on the attenuation of the phenotype. ► The five most frequent South American mutations comprise 66% of pathological alleles. |
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Bibliography: | http://dx.doi.org/10.1016/j.gene.2012.12.058 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 ObjectType-Article-2 ObjectType-Feature-1 Co-director of RK´s Doctoral Fellowship, SECyT, Universidad Nacional de Córdoba Parts of the data belong to RK’s Doctoral Thesis, Universidad Nacional de Córdoba, Argentina; defended on March, 23rd 2011. |
ISSN: | 0378-1119 1879-0038 |
DOI: | 10.1016/j.gene.2012.12.058 |