TY - JOUR
T1 - A mutation in the 5′-UTR of GRN gene associated with frontotemporal lobar degeneration
T2 - Phenotypic variability and possible pathogenetic mechanisms
AU - Puoti, Gianfranco
AU - Lerza, Maria Cristina
AU - Ferretti, Maria Giulia
AU - Bugiani, Orso
AU - Tagliavini, Fabrizio
AU - Rossi, Giacomina
PY - 2014
Y1 - 2014
N2 - Frontotemporal lobar degeneration (FTLD) is a very heterogeneous disorder. It is genetically linked to three major genes: microtubule-associated protein tau (MAPT), progranulin (GRN), and C9ORF72. In particular, mutations in GRN account for 5-10% of all cases and give rise to a wide spectrum of clinical phenotypes, ranging from behavioral frontotemporal dementia (bvFTD) to primary progressive aphasia, including progressive non-fluent aphasia (PNFA) and semantic dementia, and corticobasal syndrome (CBS). We studied a family affected by FTLD whose members showed three different phenotypes: bvFTD, PNFA, and CBS. We performed plasma progranulin measurement before any genetic analyses and, due to the low level detected, we sequenced GRN and found the new mutation EX0-5′ splice site A > G in the 5′-UTR region, where no pathogenic mutations had been previously demonstrated. Genetic analyses of MAPT and C9ORF72 were normal. GRN mRNA expression showed about 50% reduction caused by this mutation, and similar results were found for progranulin level. Testing of nonsense mediated RNA decay gave negative results, suggesting a different mechanism of mRNA degradation. In summary, the EX0-5′ splice site A > G mutation widens the GRN regions affected by null mutations, including the 5′-UTR, and confirms once more the large phenotypic variability linked to GRN mutations.
AB - Frontotemporal lobar degeneration (FTLD) is a very heterogeneous disorder. It is genetically linked to three major genes: microtubule-associated protein tau (MAPT), progranulin (GRN), and C9ORF72. In particular, mutations in GRN account for 5-10% of all cases and give rise to a wide spectrum of clinical phenotypes, ranging from behavioral frontotemporal dementia (bvFTD) to primary progressive aphasia, including progressive non-fluent aphasia (PNFA) and semantic dementia, and corticobasal syndrome (CBS). We studied a family affected by FTLD whose members showed three different phenotypes: bvFTD, PNFA, and CBS. We performed plasma progranulin measurement before any genetic analyses and, due to the low level detected, we sequenced GRN and found the new mutation EX0-5′ splice site A > G in the 5′-UTR region, where no pathogenic mutations had been previously demonstrated. Genetic analyses of MAPT and C9ORF72 were normal. GRN mRNA expression showed about 50% reduction caused by this mutation, and similar results were found for progranulin level. Testing of nonsense mediated RNA decay gave negative results, suggesting a different mechanism of mRNA degradation. In summary, the EX0-5′ splice site A > G mutation widens the GRN regions affected by null mutations, including the 5′-UTR, and confirms once more the large phenotypic variability linked to GRN mutations.
KW - Frontotemporal lobar degeneration
KW - GRN
KW - haploinsufficiency
KW - mutation
KW - phenotype
KW - progranulin
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U2 - 10.3233/JAD-140717
DO - 10.3233/JAD-140717
M3 - Article
C2 - 25024321
AN - SCOPUS:84907146942
VL - 42
SP - 939
EP - 947
JO - Journal of Alzheimer's Disease
JF - Journal of Alzheimer's Disease
SN - 1387-2877
IS - 3
ER -