Across all therapeutic classes with CNS drugs being even less efficacious than other categories, roughly 85% of prescription medicines are found ineffective in 25% of the treatment population. The figures make a bleaker picture if full and complete dosage compliance is factored into these findings. Genetic profiling to ameliorate treatment plans for a patient is still a controversial issue amongst clinicians despite the initiative in recent years for treatment programs and drugs to be tailor made for specific groups and even individuals hence soliciting a DNA profile to be taken.
However, there are certain genetic tests which fail to elucidate all possible gene mutations that can lead to disease, or lack the predictive power to even make a diagnosis in some while the inborn errors from metabolism can also not be ruled out. One positive benefit has been seen in genetic screening of infants for phenylketonuria (PKU), then with dietary intervention allows the infant to grow into a healthy adult. Possibly the dieticians of tomorrow will recommend diets customised to specific groups of people based on the presence or absence of a leptin producing Ob gene.
On the flip side however, multiple marker screening for open neural tube defects and Trisomy 21, can at best detect in 80% of pregnancies in which an open neural tube defect is present and in about 60% of pregnancies in which Down syndrome is present with such windows of error leading to a false negative. This in turn could lead to the wrong antenatal care plan, unnecessary distress for the mother or even a decision to terminate pregnancy. Then there is the ethical dilemma of screening for that disease when there is no cure. Patients susceptible to the onset of Huntingdon disease often opt for pretest counselling in order to deal with the psychological and potential discriminatory ramifications as a mutant HD gene carrier has a 100% chance of developing HD.
Could the potential here for genetic discrimination be a Grim Reaper for employers and healthcare insurance companies if confidentiality of patient data is not maintained as a patient centric market continues to popularise genetic testing?