title: The heritability of amyotrophic lateral sclerosis in a clinically ascertained United States research registry.
abstract: BACKGROUND
  The genetic basis of amyotrophic lateral sclerosis (ALS) is not entirely clear. While there are families with rare highly penetrant mutations in Cu/Zn superoxide dismutase 1 and several other genes that cause apparent Mendelian inheritance of the disease, most ALS occurs in families without another affected individual. However, twin studies suggest that all ALS has a substantial genetic basis. Herein, we estimate the genetic contribution to ALS in a clinically ascertained case series from the United States.
  
  
  RESULTS
  We used the database of the Emory ALS Center to ascertain individuals with ALS along with their family histories to determine the concordance among parents and offspring for the disease. We found that concordance for all parent-offspring pairs was low (<2%). With this concordance we found that ALS heritability, or the proportion of the disease explained by genetic factors, is between 40 and 45% for all likely estimates of ALS lifetime prevalence.
  
  
  CONCLUSIONS
  We found the lifetime risk of ALS is 1.1% in first-degree relatives of those with ALS. Environmental and genetic factors appear nearly equally important for the development of ALS.
authors: Atlanta Veterans Administration Medical Center, Atlanta, Georgia, United States of America. thomas.wingo@emory.edu
authors: Thomas S
authors: TS
authors: Wingo
authors: David J
authors: DJ
authors: Cutler
authors: Nicole
authors: N
authors: Yarab
authors: Crystal M
authors: CM
authors: Kelly
authors: Jonathan D
authors: JD
authors: Glass
mesh_terms: D000690:Amyotrophic Lateral Sclerosis / Q000453:epidemiology* / Q000235:genetics*; D035843:Biomedical Research / Q000706:statistics & numerical data*; D003710:Demography; D005260:Female; D006801:Humans; D040582:Inheritance Patterns / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D012042:Registries / Q000706:statistics & numerical data*; D014481:United States / Q000453:epidemiology