An Overview Of Genetic Testing in Newborns: A Simple Yet Comprehensive Guide On What Genetic Testing Of Newborns Actually Entails And Available Gentic Tests For Newborns.

What Is Genetic Testing In Newborns?

Genetic testing in newborns refers to the screening or laboratory tests that are carried out on newborns to identify patients that are at a higher risk for any specific genetically inherited condition or disease even before any symptoms are seen. The information obtained from such genetic testing of newborns is very vital in early diagnosis of serious genetic disorders and is helpful in providing genetic counseling to parents and families regarding their risk factor of developing the condition or disease diagnosed in their newborn child.

This testing assists in early detection of disease, especially when it might be at a very treatable stage. As a result, genetic testing in newborns is very important since it is used to detect diseases which might be serious and need proper treatment. The most important benefit is detecting the disease before symptoms commence.

Genetic Testing In Newborns: Common Tests

Newborns are commonly screened for a variety of conditions at birth using genetic testing. Among the disorders for which genetic testing in newborns is carried out, the following are most commonly available today:

Biotinidase Deficiency (BIO) an enzyme deficiency that causes seizures, hearing loss and death in severe cases. Early detection helps since the treatment is simple and requires daily doses of biotin.

Congenital Adrenal Hyperplasia (CAH) is due to lack of production of certain adrenal hormones. Early detection can prevent mortality in both boys and girls and sex misassignment in girls.

Congenital Hypothyroidism (CH) is caused by insufficient or total lack of production of thyroid hormone. Thyroid hormone replacement therapy can be started as early as 1 month of age and prevents mental as well as growth retardation.

Congenital Toxoplasmosis (TOXO) refers to infection of the fetus with a parasite ingested by the mother during pregnancy resulting in TOXO in the newborn. Early diagnosis and resultant therapy decreases the incidence of blindness, mental retardation and other serious complications.

Galactosemia (GAL) is a disorder in which the newborn shows failure to metabolize the milk sugar galactose. The classical form detected by newborn genetic testing causes cataracts, liver cirrhosis, mental retardation and/or death.

Homocystinuria (HCY) is due to an enzyme deficiency which blocks the metabolism of an amino acid leading to mental retardation, osteoporosis and other problems if not detected.

Medium Chain Acyl-CoA Dehydrogenase (MCAD) Deficiency is a common disorder which can cause sudden death when left undetected. The incidence from newborn screening is not yet known since this is a relatively recent introduction in genetic testing in newborns.

Next page: Genetic Testing for At-Risk Populations.

Genetic Testing in Newborns for At-Risk Populations

Some genetic testing in newborns is done because certain populations are at a higher risk for inheriting certain diseases. In such cases, the parents or the physician may recommend the following genetic testing in newborns:

Cystic Fibrosis (CF) in which proper treatment helps to reduce hospitalizations and improves nutritional and pulmonary outcomes. Caucasians are at an increased risk for CF.

Maple Syrup Urine Disease (MSUD) is a disorder in which the body metabolizes certain amino acids. Early detection and treatment with dietary restrictions prevents death and severe mental retardation. There is an increased risk in Mennonite community.

Phenylketonuria (PKU) refers to an enzyme defect which prevents metabolism of phenylalanine, an amino acid vital for proper brain development. Persons of European descent are at increased risk of PKU.

Sickle Cell Disease (SCD) covers a variety of disorders including sickle cell anemia (Hb-SS-Disease), Hb-SC-Disease and various thalassemias. People of African or Mediterranean origin are at an increased risk.

Some other recently introduced tests in genetic testing in newborns include other fatty acid oxidation (FAO) Disorders, organic acid (OA) disorders and urea cycle disorders (UCD). Since newborn screening for these disorders is very recent, the degree of prevalence in newborns is not yet known.

An overview of genetic testing in newborns is also carried out by the child’s health professional depending on the family medical history, ethnic group and other familial risk factors. Early detection of very rare genetic disorders provides the benefit of implementing medical home measures. The physician can also work with the family to develop a comprehensive plan of care and management of newborns. Thus genetic testing in newborns provides opportunities to improve treatment and promote evidence-based management of disorders resulting from malfunctions in genes.


1) A Look at Newborn Screening: Today and Tomorrow. Pediatrics (Supp). 2006; 117(5):pp.i

2) National Newborn Screening and Genetics Resource Center. National Newborn Screening Status Report. Updated 17 Oct 2007. Available for download at

3) Chicago Center for Jewish Genetics Disorders. Genetic screening and counseling. Available on the internet through

4) Improving Newborn Preventive Services at the Birth Hospitalization: A Collaborative, Hospital-Based Quality-Improvement Project. Pediatrics. 2007; 120(3): 481-488

5) Genetic Science Learning Center, Eccles Institute of Human Genetics, University of Utah. What are genetic disorders? Available on the internet through