Question

give a little discusstion other than abortion about the ethics issues related to Tay-Sachs, options when it comes to Tay-Sachs fetuses

Answer 1

Tay-Sachs disease (TSD) is a fatal genetic disorder mostly in children causing progressive destruction of the nervous system. IN TSD, the enzyme hexosaminidase-A (Hex-A) is absent which is normally involved in removal of the lipid GM2 ganglioside accumulates abnormally in nerve cells of the brain. As a result, the GM2 ganglioside accumulates in nerve cells causing damage. This damage in children starts early in pregnancy. A baby with TSD will appear normal until 6 months of age after which development slows. There is recurrent seizures and reduced mental function. The infant cannot crawl, sit, turn, or reach out. Eventually, the child may become blind, and is cognitively impaired, paralyzed, and non-responsive. Death usually occurs by age of 5. A rarer late onset TSD is seen in adults that causes neurological and intellectual impairment. There is no cure for TSD.

TSD is caused by a mutation in a gene on Chromosome 15 that produces Hex-A. It is autosomal recessive. Hence, two copies of this mutated allele is required to cause the disease. A simple blood test can diagnose carriers. The blood enzyme assay measure the level of Hex-A. Carriers have less Hex-A in their blood than non-carriers. DNA testing may be carried out to detect mutation in this gene.

Parents of children with TSD have issues as these children require increased daily care and treatments, which creates a financial burden. However, carrier testing may put a pressure on couples not to have children

Prenatal genetic testing can be carried out by amniocentesis or chorionic villus sampling. Chorionic Villus sampling is performed on 11^th week of pregnancy, wherein a tiny piece of placenta is removed for analysis. Amniocentesis can be performed during 16^th week of pregnancy wherein the amniotic fluid is removed around the fetus. However, both these procedures are risky and may harm the fetus.

A method to avoid amniocentesis or chorionic villus sampling is to use assisted reproductive technology for a healthy baby. Preimplantation genetic diagnosis (PGD) is a genetic screen for identification of genetic chromosomal abnormalities in pre-implantation stage human embryo. This diagnosis is done in conjunction with in vitro fertilization (IVF) to screen for genetic abnormalities before the embryo is put in the mothers uterus. PGD is effective in preventing heritable genetic disease. As a result, it eliminates the dilemma of pregnancy termination following unfavorable prenatal diagnosis. Healthy embryos are then implanted into the mother’s uterus.

Some invidual’s believe that life starts at conception. Hence, a Preimplantation embryo is considered as live individuals. PGD will therefore be considered as abortion. A way to overcome is to use donor gametes. However, this will cause issues as half the genome will not be from the parents. Religious beliefs will prevent use of donor gametes.

TSD is more frequent in Ashkenazi Jewish population. Detection of carriers in such population will lead to stigmatization. All carriers need to be counseled and educated in effects of Tay-Sacs diseases and well as effects of PGD and use of donor gametes. PGD involves removal of single cells from embryos. There may be damage to the embryo during PGD. Similarly, chromosomal abnormalities may not always be detected in PGD due to mosaic pattern or expression.

PGD and IVF are expensive procedures that cannot be afforded by all. In addition, as few embryos are available, IVF may not always be successful. Adoption is one method for such couples to have children.

Newborn screening is done after birth. This approach may not be helpful as TSD children mostly never survive. However, it may help reduce the lifespan, as it will halt development of symptoms.