Amyotrophic lateral sclerosis and osteoporosis: a two-sample Mendelian randomization study

Area of Science:

• Neuroscience
• Bone Metabolism
• Genetics

Background:

• Observational studies suggest a link between amyotrophic lateral sclerosis (ALS) and osteoporosis.
• Previous findings were inconsistent, and a causal relationship remains uninvestigated.

Purpose of the Study:

• To investigate the potential causal effect of amyotrophic lateral sclerosis (ALS) on osteoporosis using a two-sample Mendelian randomization approach.

Main Methods:

• Utilized genetic instrumental variables for ALS from a large GWAS.
• Employed bone mineral density phenotypes (femoral neck, lumbar spine, forearm) from another GWAS.
• Applied various Mendelian randomization methods including IVW, MR Egger, and weighted median, with sensitivity analyses for heterogeneity and pleiotropy.

Main Results:

• Selected 10 single nucleotide polymorphisms (SNPs) as genetic proxies for ALS.
• Mendelian randomization analyses, including Inverse Variance Weighted (IVW), showed no statistically significant causal effect of ALS on bone mineral density in the femoral neck, lumbar spine, or forearm.
• Sensitivity analyses did not detect significant heterogeneity or pleiotropy.

Conclusions:

• This Mendelian randomization study found no evidence of a causal relationship between amyotrophic lateral sclerosis and osteoporosis.
• Discrepancies with observational studies may be due to confounding factors like physical inactivity and muscle atrophy secondary to ALS.