Ampath Laboratories DxINSIGHTS - Issue 3 - May 2023

Introduction

An introduction to genetics and genetic testing

Chromosomes and genes are the basis of inheritance. In this article, we discuss how differences in chromosomes and genes cause genetic disorders. We also discuss the importance of population genetics in test determination and the most common genetic conditions that may be encountered locally.

Family history: A genetic screen

Taking a family history is an important start in identifying patients at increased risk for a wide variety of health conditions. The value of a family history in the context of rare single-gene or chromosomal disorders is well recognised but is also important in the more common complex adult onset conditions.

Genetic counsellors: What are we really about?

Genetic counsellors are trained healthcare professionals, registered with the HPCSA after completing an MSc (Med) degree in genetic counselling. Genetic counsellors provide information and support to individuals or families who have members with birth defects and/or genetic conditions.

Test in focus

Genetic testing in breast cancer (BRCA1 and BRCA2 testing)

Breast cancer is the most frequently diagnosed cancer worldwide and a leading cause of cancer-related deaths. It is a genetically complex and heterogeneous disease with familial clustering identified more frequently than with other malignancies.

Test in focus

Genetic testing for familial hypercholesterolaemia

Familial hypercholesterolaemia (FH) is one of the most common inherited disorders in the world. Familial hypercholesterolaemia is especially prevalent within the South African Afrikaner, Jewish and Indian communities, where as many as one in 72 are believed to be affected. Despite this high prevalence, many of those affected remain undiagnosed and untreated, putting themselves and their families at risk of life-threatening atherosclerotic complications.

Improving patient care with pharmacogenomic testing

Pharmacogenomic testing (PGT) investigates the way an individual’s genetic make-up influences their response to various medications. Small genetic changes within known pharmacogenes (such as the cytochrome P450 system) affect how well the relevant P450 enzyme functions with regard to the absorption, distribution, metabolism or excretion of target medications.

The role of non-invasive prenatal testing (NIPT) in screening for foetal chromosomal abnormalities

It is estimated that a chromosome abnormality is present in one out of 150 live births. These chromosome abnormalities can occur at any maternal age, but become more likely as women get older. Aneuploidy refers to an abnormal amount of chromosomes due to either an additional chromosome present (e.g. Trisomy 21) or a missing chromosome (e.g. Monosomy X).