A couple plans to have children.Since breast cancer has occurred on both sides of the family, they are concerned about their BRCA1 status and decide to have their genomes sequenced.With the guidance of a genetic counselor, they evaluate the results and are relieved to find that neither carries a BRCA1 allele associated with increased incidence of breast and ovarian cancer.However, they are upset to discover that they are both heterozygous for the gene that causes tissue-nonspecific alkaline phosphatase (TNSALP) deficiency, also known as hypophosphatasia.This disease affects osteoblasts and chondrocytes and results in impaired bone mineralization.One of the prospective parents carries a mutation associated with the severe form, which results in fatality not long after birth.Which test could ensure that the mother does not become pregnant with a fetus homozygous for hypophosphatasia?

Question

Quizplus · Accepted Answer

Preimplantation screening involves testing embryos created through in vitro fertilization before they are implanted in the mother's uterus. This allows for selection of embryos that do not carry the homozygous mutation for hypophosphatasia, ensuring that the child will not be affected by the severe form of the disease. Prenatal screening, postnatal screening, amniocentesis, and chorionic villus sampling all involve testing the fetus or newborn after conception has already occurred, and do not allow for selection of unaffected embryos.

A Couple Plans to Have Children