Genetic Disease Tests
Types of Molecular Genetic Tests
Beta Thalassemia (genetic anaemia)
It is a blood disorder that reduces the production of haemoglobin, leading to severe anaemia in affected individuals. This condition occurs most frequently in people from Mediterranean countries, North Africa, the Middle East, India, Central Asia, and Southeast Asia
Sickle cell anaemia (SCA) (red blood cell disorder)
SCA is an autosomal recessive disorder of the blood that affects haemoglobin, the molecule in red blood cells that delivers oxygen to cells throughout the body. Characteristic features of this disorder include anaemia, repeated infections, and periodic episodes of pain. The disease is estimated to occur in 1 in 10 people of African descent.
Fanconi anaemia (FA)
FA is an inherited anaemia that leads to bone marrow failure (aplastic anaemia). Although primarily a blood disorder, it may affect many other systems of the body. Many patients eventually develop acute myelogenous leukemia (AML).
Breast, Ovarian and Prostate Cancer
BRCA1 and BRCA2 are major genes related to hereditary breast cancer. Women who have inherited mutations in these genes, have a high risk of developing particularly breast and ovarian cancer during their lifetimes. Male BRCA2 carriers are at an increased risk of prostrate and pancreatic cancer. Hereditary breast cancers tend to occur earlier in life than sporadic cases, occur more frequently in families and are more likely to involve both breasts. Founder mutations are common in specific populations, such as the Ashkenazi Jewish and Afrikaner populations.
Multiple endocrine neoplasia type 2 (MEN2) (tumours of endocrine glands):
MEN2 is an autosomal dominant predisposition cancer syndrome, affecting the endocrine system. It is characterized by tumours of the thyroid and adrenal glands. Three subtypes exist, including Familial medullary thyroid carcinoma (FMTC), all caused by mutations in the RET protooncogene.
It is the inability to metabolize lactose, because the required enzyme lactase is absent in the intestinal system or its availability is lowered. The frequency of decreased lactase activity ranges from as little as 5% in northern Europe, up to 71% for Sicily, to more than 90% in some African and Asian countries.
Crohn’s Disease and Ulcerative Colitis
The exact cause of this inflammatory disease of the intestines is still unknown, but the interplay of environmental factors in a genetically predisposed host is thought to initiate disease. Parents, siblings or children of people with CD are 3 to 20 times more likely to develop the disease.
The majority of cases of genetic deafness (70 percent to 80 percent) are nonsyndromic, i.e. hearing loss that is not associated with other signs and symptoms.
HEART DISEASE, THROMBOSIS AND CHOLESTROL
Apolipoprotein E-associated lipid disorders (clogged arteries)
Lipid and lipoprotein abnormalities are extremely common in the general population and are regarded as a risk factor for cardiovascular disease due to the influence of cholesterol on atherosclerosis.
Factor V Leiden (venous thrombosis):
Factor V Leiden (R506Q mutation) is the most common genetic risk factor for venous thrombosis. It has also been associated with an increased risk of pregnancy loss.
Familial hypercholesterolemia (high cholesterol)
Identification of individuals or families with a genetic predisposition to high levels of cholesterol, particularly LDL or “bad cholesterol”. Very common in the Afrikaner population in South Africa, affecting 1 in 80 people. This condition results in an increased risk for early cardiovascular disease.
Factor II (premature clotting in blood vessels)
Prothrombin thrombophilia is another inherited disorder of blood clotting, leading to an increased tendency to form abnormal blood clots in blood vessels. It affects approximately 1 in 50 people in the Caucasian population.
Factor V Leiden (venous thrombosis)
Factor V Leiden (R506Q mutation) is the most common genetic risk factor for venous thrombosis also been associated with an increased risk of pregnancy loss.
Homocysteine (blood clots and cardiovascular disease – MTHFR)
Elevated levels homocysteine in the blood, caused by defects in the genes responsible for homocysteine breakdown, is a powerful risk factor for cardiovascular disease and thrombosis
PAI-1 Gene Mutation (coronary artery disease)
Variations in Plasminogen Activator Inhibitor (PAI-1) gene are associated with an increased risk for arterial and venous thrombosis, coronary artery disease and ischemic stroke.
African iron overload (AIO) (previously known as African siderosis):
AIO occurs in as many as 10% of individuals of African descent. It is characterized by the accumulation of large amounts of iron in the reticuloendothelial cells of the liver, spleen and bone marrow as well as in hepatocytes.
Ferroportin disease (iron loading disease)
Ferroportin disease, also known as hemochromatosis type 4, is characterized by the abnormal accumulation of iron in the body. Ferroportin disease is caused by mutations of the SLC40A1 gene.
Hereditary Haemochromatosis (HH) (iron overload disorder):
HH is characterized by progressive iron overload, with the main feature being excessive absorption of dietary iron. Early symptoms of HH are nonspecific and may include fatigue, joint pain, abdominal pain, and loss of sex drive. Later signs and symptoms can include arthritis, liver disease, diabetes, cardiac abnormalities, and skin discoloration. If HH is diagnosed early, treatment is effective and many symptoms are reversible.
Duchenne and Becker Muscular Dystrophy (progressive muscle weakness)
Duchenne Muscular Dystrophy (DMD) is the most common and severe form of childhood muscular dystrophy, affecting approximately 1 in every 3500 male births. BMD is clinically similar to DMD, but milder. Both conditions are inherited in an X-linked recessive manner and are caused by mutations in the dystrophin gene.
Myotonic dystrophy (wasting of the muscles)
Myotonic dystrophy is the most common heritable neuromuscular disorder. It is inherited in an autosomal dominant manner and is characterized by progressive muscle wasting and weakness, particularly in the lower legs, hands, neck, and face.
Tay-Sachs disease (mental and physical deterioration)
Tay-Sachs disease is an inherited neurological disorder that progressively that severely affects the nervous system, leading to mental and physical deterioration. Although rare in the general population, it is common in the Ashkenazi Jewish population.
Friedreich’s ataxia is the most common inherited ataxia. It is an autosomal recessive inherited disease of the nervous system, causing a loss of muscle coordination that gradually worsens over time.
Hirschsprung’s disease (congenital aganglionic megacolon)
Hirschprung’s disease is an important genetic cause of functional intestinal obstruction. RET mutations have been shown to account for 40-50% of familial cases and 15-20% of sporadic cases
Alpha-1 antitrypsin deficiency (glycoprotein deficiency affecting lungs and liver)
It is an inherited disorder that may cause lung disease and liver disease. The earliest symptoms of Alpha-1 antitrypsin deficiency usually occur between the ages of 20 to 50 and include: shortness of breath, reduced ability to exercise, and wheezing.
Cystic Fibrosis (sodium channel pathology leading to build-up of mucus)
Cystic Fibrosis is the most common life-limiting autosomal recessive disorder in Caucasian populations. It is a multisystem disorder with variable clinical symptoms, but is usually characterized by the triad of: recurrent respiratory infections, pancreatic insufficiency causing malabsorption of nutrients and abnormally high sweat chloride levels
Variegate porphyria (photosensitivity)
It is an autosomal dominant inherited disorder of porphyrin-heme metabolism. Manifestations may include skin photosensitivity, systemic symptoms arising from neurologic symptoms, or both. Variegate porphyria is most common in the Afrikaner population of South Africa; about 3 in 1000 people in this population have the genetic change that causes this form of the disorder.