Possibilities and limitations of the trio genome.

A family came from a remote region. Young healthy parents. There is a family history of hereditary diseases (heart disease, bone pathology). The first child was born with gigantism of one limb and a heart defect. The child underwent several surgeries for gigantism of the limb. The second child was born healthy. The family plans to have more children.

Doctors at the place of residence suspected a specific genetic syndrome, the diagnosis of which is specified by a certain genetic diagnostic method. The analysis was carried out, but the diagnosis of the child was not confirmed. Parents applied to the Foundation to clarify the diagnosis using a whole genome sequencing. The study was conducted first on a child. The causes of the disease were not identified, but it was recommended to supplement the whole genome study of the child with whole genome sequencing of both parents.

This family belongs to the rare case when even a genome-wide study in the trio format (mother, father and child) did not allow us to identify the genetic cause of the disease in the child. But as an unexpected finding, it was found that the child's parents are carriers of an absolutely identical genetic breakdown, which leads to the development of hereditary hearing loss in offspring. The probability of having a child with hearing loss in such a family is 25%. Parental kinship is also not ruled out.

Since the family plans to have more children, information about the carriage of a genetic disease in the family will be useful.

The genome recording of all three family members was handed out (on electronic media), which will allow in the future (after 1-2 years) doctors at the place of residence to revise the data obtained without re-conducting a genetic study, taking into account new knowledge about the genome that will accumulate over the coming 1-2 years. We hope that the cause of the disease in the family will be established.