Genetic testing, also known as DNA testing, allows the determination of bloodlines and the genetic diagnosis of vulnerabilities to inherited diseases. Genetic tests are done by analyzing small samples of blood or body tissues.
They determine whether you, your partner, or your baby carry genes for certain inherited disorders. For deoxyribonucleic acid (DNA) screening, only a very tiny bit of blood, skin, bone, or other tissue is needed.
The following list includes features that might suggest that your child has a genetic disorder. However, some of these characteristics are commonly found in people without a disorder. You’ll want to check with your doctor if your child has at least two of the following features;
- Ear abnormalities.
- Unusually shaped eyes.
- Different colored eyes.
- Facial features that are unusual or different from other family members.
- Brittle or sparse hair.
- Excessive body hair.
- White patches of hair.
- Large or small tongue.
- Misshapen teeth.
- Missing or extra teeth.
- Loose or stiff joints.
- Unusually tall or short stature.
- Webbed fingers or toes.
- Excessive skin.
- Unusual birthmarks.
- Increased or decreased sweating.
- Unusual body odor.
Once a person decides to proceed with genetic testing, a medical geneticist, genetic counselor, primary care doctor, or specialist can order the test after obtaining informed consent . Genetic tests are performed on a sample of blood, hair, skin, amniotic fluid (the fluid that surrounds a fetus during pregnancy), or other tissue.
For example, a medical procedure called a buccal smear uses a small brush or cotton swab to collect a sample of cells from the inside surface of the cheek. Alternatively, a small amount of saline mouthwash may be swished in the mouth to collect the cells.
The sample is sent to a laboratory where technicians look for specific changes in chromosomes, DNA, or proteins, depending on the suspected disorders, often using DNA sequencing . The laboratory reports the test results in writing to the person’s doctor or genetic counselor.
Some Genetic Diseases Diagnosable With Genetic Blood Testing
Breast and ovarian cancer : BRCA genes belong to a class known as tumor suppressors, according to the National Cancer Institute (NCI). When mutated, they can allow uncontrolled cell growth. Women with mutations in these genes are about five times more likely to develop breast cancer than those without them, and are between 15 and 40 times more likely to develop ovarian cancer, according to the NCI. These mutations are more prevalent among women of Ashkenazi Jewish heritage.
African iron overload : This involves over-absorption of iron; accumulation of iron in vital organs (heart, liver, pancreas); organ damage; heart disease; cancer; liver disease; arthritis; diabetes; infertility; and impotence.
Alpha-1 antitrypsin deficiency : This condition involves obstructive lung disease in adults; liver cirrhosis during childhood; when a newborn or infant has jaundice that lasts for an extended period of time (more than a week or two), an enlarged spleen, ascites (fluid accumulation in the abdominal cavity), pruritus (itching), and other signs of liver injury; persons under 40 years of age that develops wheezing, a chronic cough or bronchitis, is short of breath after exertion and/or shows other signs of emphysema (especially when the patient is not a smoker, has not been exposed to known lung irritants, and when the lung damage appears to be located low in the lungs).
Crohn’s disease : Inflammation confined to the colon; abdominal pain and bloody diarrhea; anal fistulae and peri-rectal abscesses can also occur.
Cystic fibrosis : Large amount of abnormally thick mucus in the lungs and intestines that leads to congestion, pneumonia, diarrhea and poor growth.
Fanconi anaemia : Predisposition of acute myeloid leukemia; skeletal abnormalities; radial hypoplasia and vertebral defect and other physical abnormalities, bone marrow failure (pancytopenia), endocrine dysfunction, early onset osteopenia/osteoporosis and lipid abnormalities, spontaneous chromosomal breakage exacerbated by exposure to DNA cross-linking agents.
Fragile-X syndrome : Mental retardation or learning disabilities of unknown etiology; autism or autistic-like characteristics; women with premature menopause. Subtle dysmorphism, log face with prominent mandible and large ears, macroorchidism in postpubertal males, behavioral abnormalities, due to lack of FMR1 in areas such as the cerebral cortex, amygdala, hippocampus and cerebellum.
Hereditary hemochromatosis : Over-absorption of iron; accumulation of iron in vital organs (heart, liver, pancreas); organ damage; heart disease; cancer; liver disease; arthritis; diabetes; infertility; impotence.
Myotonic muscular dystrophy : Affects skeletal and smooth muscle as well as the eye, heart, endocrine system, and central nervous system; clinical findings, which span a continuum from mild to severe, have been categorized into three somewhat overlapping phenotypes: mild, classic, and congenital.
Sickle cell anaemia : Variable degrees of hemolysis and intermittent episodes of vascular occlusion resulting in tissue ischemia and acute and chronic organ dysfunction. Complications include anemia, jaundice, predisposition to aplastic crisis, sepsis, cholelithiasis, and delayed growth. Diagnosis suspected in infants or young children with painful swelling of the hands and feet, pallor, jaundice, pneumococcal sepsis or meningitis, severe anemia with splenic enlargement, or acute chest syndrome.
Tay–Sachs disease : Lipids accumulate in the brain; neurological dysfunction; progressive weakness and loss of motor skills; decreased social interaction, seizures, blindness, and total debilitation.