"You have shown me my end": attitudes toward presymptomatic testing for familial amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a lethal degenerative motor neuron disease. Approximately, 5-10% of cases of ALS are familial (FALS), inherited primarily as an autosomal dominant trait. Recently, mutations in Cu/Zn superoxide dismutase (SOD1) have been identified; 15-20% of familial cases carry this mutation, providing a marker for diagnosis, carrier testing, and prenatal detection. We assessed understanding of genetics of FALS in relatives of patients cared for at the Forbes Norris MDA/ALS Research Center in San Francisco. A total of 25 participants completed a questionnaire and semistructured interview. Of these, 60% would have gene testing for themselves; 36% believed testing of children or adolescents was a good idea. Overall knowledge of genetics of FALS was limited. Also, 24% of respondents understood the inheritance pattern of FALS; 64% were aware that not all individuals who had the gene would show symptoms in their lifetime. Families were confused about whether they would receive results from linkage studies. We recommend that: (1) physicians refer relatives of newly diagnosed individuals for genetic counseling and possibly psychological counseling; (2) investigators ensure that participants comprehend the purpose of gene identification is for research, not disclosure of individual results; (3) families be helped to understand how to keep abreast of medical and genetic advances; (4) following the model of Huntington disease (HD), consensus guidelines for FALS genetic counseling and testing be developed.