Causal association of type 2 diabetes with amyotrophic lateral sclerosis: new evidence from Mendelian randomization using GWAS summary statistics

Table 2 GWAS data sets used in the present MR analysis

Traits	Pop	k₁/k₀	Sample size (case/control)	Data source
ALS	EUR		20,806/59,804	AVS [49]
T2D	EUR	67/139	62,892/596,424	PCTG [38]
BMI	EUR	91/95	339,224	GIANT [60]
Fasting glucose	EUR	35/35	133,010	MAGIC [61]
Fasting insulin	EUR	14/14	108,557	MAGIC [61]
HbA1c	EUR	36/37	123,665	MAGIC [62]
ALS	EAS		1234/2850	Benyamin [63]
T2D	EAS	34/72	36,614/155,150	JENGER [64]

Here k₁ is the final number of instruments employed in the analysis while k₀ is the number of candidate instruments. For T2D, we conducted stringent procedures (Fig. 1) to carefully choose instruments. For the remaining exposures, we performed the standard B1 and B2 selection procedures shown in Fig. 1 to select the final set of instrumental variables
T2D type 2 diabetes, BMI body mass index, ALS amyotrophic lateral sclerosis, HbA1c hemoglobin A1c, GIANT Genetic Investigation of ANthropometric Traits Consortium, MAGIC Meta-Analyses of Glucose and Insulin-related traits Consortium, JENGER Japanese ENcyclopedia of GEnetic associations by Riken, CHN China Health and Nutrition Survey, AVS ALS Variant Server, PCTG Program in Complex Trait Genomics, EUR European, EAS East Asian

ISSN: 1741-7015