Analysis carriers or family analysis
For diagnose the patient or to find variants with high probability of being related to their disease is important to demonstrate:
1) In cases of recessive inheritance found the source of the variants (each must come from one parent: “trans”) and co-segregation in the family (all affections must have both versions and none of unaffected individuals may have both variants)
2) If any family history and be a dominant disease is important to demonstrate the co-segregation of the variant affects family members and their absence in unaffected individuals
3) If sporadic absence dominant diseases that variant in the parents (“de novo”)
When inside a family has been diagnosed with a hereditary disease have been detected variants underlying disease, can provide analysis of these variants in DNA samples of chorionic villi (fetal tissue) in case of new pregnancies to determine whether they are present or no.