The cause is that which is completely responsible for the effect. In all likelihood, there are no causes anywhere in nature.
Genetic mutations are often profound contributors to disease, even a defining characteristic of a disease, but they do not cause the diseases named for them. If they did, the phenotype would be exactly the same in every person with the mutation. It never is. Here is an example where the phenotypic range of a genetic disease is humongous.
Consider this unusual genetic disease
“Biotin-Thiamine-Responsive Basal Ganglia Disease
Genotype-phenotype correlations are poor. Despite having the same pathogenic variants, children from the same family have extremely variable outcomes, ranging from normal to severely handicapped [Alfadhel et al 2013].”