Association between the Angiogenin ( ANG ) K17I variant and amyotrophic lateral sclerosis risk in Caucasian: a meta-analysis

The study purpose is to perform a meta-analysis to help resolve the debate of whether the Angiogenin ( ANG ) K17I variant is associated with amyotrophic lateral sclerosis (ALS) risk in Caucasian. Three literature databases were searched for eligible studies published up to January 8, 2015: PubMed, Embase and Web of Science using the following search terms: amyotrophic lateral sclerosis or ALS and Angiogenin or ANG. Five eligible articles were identified, which reported 6 case–control studies and a total of 2326 cases and 3799 controls. The overall results suggested low frequencies of the K17I variant in Caucasian patients (10/2326, 0.43 %) and controls (6/3799, 0.16 %). There is no difference in the variant frequencies between patients with FALS or SALS ( p = 0.069). Analysis of pooled odds ratios (ORs) and 95 % confidence intervals (CIs) revealed that the ANG K17I variant increases the risk for ALS (AT vs. AA: OR 2.65, 95 % CI 1.05–6.66, p = 0.038) and familial ALS (FALS) (AT vs. AA: OR 11.81, 95 % CI 2.11–66.15, p = 0.005) but not for sporadic ALS (SALS) (AT vs. AA: OR 1.63, 95 % CI 0.55–4.82, p = 0.378). The ANG K17I variant is rare in Caucasian patients and controls and increases the risk for ALS and FALS but not for SALS in Caucasian populations. Further well-designed studies with larger samples are needed to validate these results.