Genetic counseling

Whatever the inheritance, it is important to emphasize that this is nobody’s fault.

Unique, 2017

Could it happen again?

Bohring-Opitz syndrome (BOS) is inherited in an autosomal dominant manner. In most cases BOS is caused by a genetic change or mutation in the ASXL1 gene which occurred in the formation of the egg or sperm from which the child was conceived, but not inherited from either parent so the risk of having another child with the condition is very low. This is called a new or de novo mutation.

Very occasionally a change in ASXL1 can be found in some of the cells of the mum or dad, this is called mosaicism and can lead to further children having the condition.

For these reason genetic counselling is recommended for families wanting to have further children.

Genetic counseling is the process of providing individuals and families with information on the nature, mode(s) of inheritance, and implications of genetic disorders to help them make informed medical and personal decisions. The following section deals with genetic risk assessment and the use of family history and genetic testing to clarify genetic status for family members; it is not meant to address all personal, cultural, or ethical issues that may arise or to substitute for consultation with a genetics professional.

— ED.
Parents

Most individuals with BOS reported to date have the disorder as a result of a de novo ASXL1 pathogenic (= able to cause disease) variant.

Recommendations for the evaluation of parents of a child with an apparent de novo ASXL1 pathogenic variant include molecular genetic testing.

Siblings

Most affected individuals reported to date have had a de novo ASXL1 pathogenic variant, suggesting a low risk to sibs.

If the ASXL1 pathogenic variant found in the patient cannot be detected in the leukocyte DNA of either parent, the recurrence risk to sibs is estimated to be 1% because of the theoretic possibility of parental germline mosaicism.

Ofspring

Individuals with Bohring-Opitz Syndrome are not known to reproduce.

Other Family Members

Given that most patients with Bohring-Opitz Syndrome reported to date have the disorder as a result of a de novo ASXL1 pathogenic variant, the risk to other family members is presumed to be low.

Family planning

The optimal time for determination of genetic risk and discussion of the availability of prenatal/preimplantation genetic testing is before pregnancy.

It is appropriate to offer genetic counseling (including discussion of potential risks to offspring and reproductive options) to parents of affected individuals.

Prenatal testing

Once the ASXL1 pathogenic variant has been identified in an affected family member, prenatal testing and preimplantation genetic testing are possible.



Sources:

Unique, 2017

Bianca Russell, 2018