Mosaic trisomy 14 is usually new (or de novo) in the person who has it, which means that neither parent has mosaic trisomy 14. If the condition is new, it is most likely not necessary to test other family members. Chromosome testing may be performed on the parents to see if they have a chromosome change called a translation that makes it more likely for their children to inherit this disorder. You can check with your healthcare provider or a local genetic counselor if you have additional questions about who in your family should be tested.