TY - JOUR
T1 - Characterization of the c9orf72 GC-rich low complexity sequence in two cohorts of Italian and Turkish ALS cases
AU - Corrado, Lucia
AU - Tiloca, Cinzia
AU - Locci, Clarissa
AU - Bagarotti, Alessandra
AU - Hamzeiy, Hamid
AU - Colombrita, Claudia
AU - De marchi, Fabiola
AU - Barizzone, Nadia
AU - Cotella, Diego
AU - Ticozzi, Nicola
AU - Mazzini, Letizia
AU - Nazli Basak, A. Y.S.E.
AU - Ratti, Antonia
AU - Silani, Vincenzo
AU - D’alfonso, Sandra
N1 - Publisher Copyright:
© 2018, © 2018 World Federation of Neurology on behalf of the Research Group on Motor Neuron Diseases.
PY - 2018/7/3
Y1 - 2018/7/3
N2 - Large expansions of a noncoding GGGGCC repeat in the C9orf72 gene are the main cause of amyotrophic lateral sclerosis (ALS). The GGGGCC repeat is contiguous with another GC-rich region. Recent studies reported a significantly higher frequency of insertions/deletions within the GC-rich region in patients carrying the GGGGCC expansion. A GTGGT motif comprised within the GC-rich region, which joins two 100% GC sequences, was frequently deleted, supporting the hypothesis that these deletions could make the region more prone to slippage and pathological expansion. To confirm this hypothesis, we sequenced the GC-rich region adjacent the GGGGCC repeat in ALS patients, 116 C9orf72 expansion carriers, 219 non-carriers, and 223 healthy controls, from Italian and Turkish cohorts. Deletions were significantly more frequent in C9orf72 expansion carriers (6%) compared to non-carrier ALS patients (0.46%, OR =14.00, 95% CI =1.71–306.59, p = 0.003), to controls (0%, OR =16.29, 95% CI =2.12–725.99, p = 4.86 × 10−4) and to the whole cohort of non-carriers (0.2%, OR =28.51, 95% CI =3.47–618.91, p = 9.58 × 10−5). Among expansion carriers, deletions with or without the GTGGT motif were equally distributed (4 vs. 3). The frequency of insertions was not statistically different between C9orf72 expansion carriers and any other group including the whole cohort of non-carriers (p = 0.439, Fisher’s exact test). Our data confirmed the association between deletions within GC-rich region and the GGGGCC expansion in Italian and Turkish cases, although we did not confirm a role of the GTGGT element deletion. Further studies will be therefore necessary to assess the causal relationships between contiguous deletions of the GC-rich region and the GGGGCC expansion.
AB - Large expansions of a noncoding GGGGCC repeat in the C9orf72 gene are the main cause of amyotrophic lateral sclerosis (ALS). The GGGGCC repeat is contiguous with another GC-rich region. Recent studies reported a significantly higher frequency of insertions/deletions within the GC-rich region in patients carrying the GGGGCC expansion. A GTGGT motif comprised within the GC-rich region, which joins two 100% GC sequences, was frequently deleted, supporting the hypothesis that these deletions could make the region more prone to slippage and pathological expansion. To confirm this hypothesis, we sequenced the GC-rich region adjacent the GGGGCC repeat in ALS patients, 116 C9orf72 expansion carriers, 219 non-carriers, and 223 healthy controls, from Italian and Turkish cohorts. Deletions were significantly more frequent in C9orf72 expansion carriers (6%) compared to non-carrier ALS patients (0.46%, OR =14.00, 95% CI =1.71–306.59, p = 0.003), to controls (0%, OR =16.29, 95% CI =2.12–725.99, p = 4.86 × 10−4) and to the whole cohort of non-carriers (0.2%, OR =28.51, 95% CI =3.47–618.91, p = 9.58 × 10−5). Among expansion carriers, deletions with or without the GTGGT motif were equally distributed (4 vs. 3). The frequency of insertions was not statistically different between C9orf72 expansion carriers and any other group including the whole cohort of non-carriers (p = 0.439, Fisher’s exact test). Our data confirmed the association between deletions within GC-rich region and the GGGGCC expansion in Italian and Turkish cases, although we did not confirm a role of the GTGGT element deletion. Further studies will be therefore necessary to assess the causal relationships between contiguous deletions of the GC-rich region and the GGGGCC expansion.
KW - ALS
KW - C9orf72
KW - deletion
KW - indel
KW - low complexity sequence
KW - repeat
UR - http://www.scopus.com/inward/record.url?scp=85042916340&partnerID=8YFLogxK
U2 - 10.1080/21678421.2018.1440407
DO - 10.1080/21678421.2018.1440407
M3 - Article
SN - 2167-8421
VL - 19
SP - 426
EP - 431
JO - Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration
JF - Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration
IS - 5-6
ER -