The family was looking forward to the birth of their first child, but the girl was born seriously ill. Various medical examinations did not reveal the cause of the disease. The parents decided to have a second child, but the second girl also had a similar disease. Again, the medical examinations could not establish the cause. At the expense of Charity Fund Life Genome, the studies of the whole genome of the two girls and their parents were carried out, which allowed to identify the cause of the disease and its carriers − the parents. The girls inherited two different special breakdowns of the same gene from two parents. It took 10 years to finally establish the genetic basis of the disease. These findings will allow the parents to give birth to a healthy baby in the future and provide proper care for their children.