Newborn screening and a variety of screening methods

What is screening?

Screening is a method to identify healthy people from seemingly healthy people at higher risk for a particular disease. In the case of people who are considered high-risk, additional tests are needed for a final diagnosis.

What is newborn screening?

Newborn screening is a type of screening test used for the early detection of congenital metabolic abnormalities or diseases and is done to diagnose the diseases at birth. Delays in diagnosis and treatment can lead to mental and physical problems, such as Paralysis, intellectual disability, malnutrition, Dysarthria, Down syndrome, etc.

What diseases are screened?

Congenital hypothyroidism (CHT): This disease reduces the level of thyroid hormones and causes severe intellectual disability (ID). Early diagnosis and medical treatment will prevent any problems and the newborn will continue to grow normally.

Phenylketonuria: Phenylalanine is one of the essential amino acids in the body. The genetic defect in the enzymes that cause the consumption of phenylalanine in the metabolic cycle increases its level in the body and its appearance in the patient. If left untreated, a high level of phenylalanine can damage brain tissue and lead to intellectual disability. Early diagnosis and treatment with special diets will help the infant grow normally.

Galactosemia: Babies with this disease will be unable to use the sugar in milk (galactose) due to a genetic disorder in the production of some enzymes. Consequently, blood galactose levels rise and can cause cataracts and severe liver and brain damage. The first sign is persistent and severe vomiting. If left untreated, it can lead to dangerous side effects.

enlargement and congenital hypertrophy of the adrenal glands: In this disease, the body is unable to produce the hormone cortisol, and this deficiency causes physical and mental retardation, as well as boyish traits in girls.

Favism: Favism is a genetic disease in which one of the essential enzymes of red blood cells is reduced. As a result, it destructs red blood cells (hemolysis) after consuming oxidants such as some drugs and beans. The patient quickly develops severe anemia with shock and lethargy, and the disease in infants can prolong the course of jaundice.

Maple syrup disease: A congenital disease caused by impaired absorption and utilization of several types of amino acids. As a result of this disease, the level of some amino acids in the blood increases, and it causes an odor similar to the smell of burnt sugar or maple sap on body fluids, including urine. Accumulation of these amino acids leads to severe mental retardation and even death.

Advantages of newborn Screening

newborn screening is one of the improvements in child health in the last century, and there have been many technological advances in neonatal screening. Newborn screening has many benefits, including:

• Ability to diagnose multiple metabolic diseases in newborn dried blood samples at birth
• Low cost of diagnosis and prevention at birth, compared to the cost of treatment at older ages
• Early treatment and intervention of at least 12,000 infants each year in the United States with genetic, hearing, and endocrine disorders
• Contributing to the health of the community, etc.

These benefits have led governments to take effective action to raise awareness of newborn screening and its benefits. In June 2018, the American Society of Hematology (ASH) launched a campaign to fight sickle cell disease in Africa and called on governments, especially in sub-Saharan Africa, to invest in newborn screening. In addition, the US government runs programs every year, such as the Quality Assurance Program for newborn Screening (NSQAP) at the Centers for Disease Control and Prevention (CDC), with the participation of various countries.

Classification of newborn screening based on the technology used

• Tandem Mass Spectrometry LC-MS/MS
• DNA testing
• Electrophoresis
• Pulse oximetry
• Enzyme-based assays
• Hearing screening technology

Classification of newborn screening by type of test

• Dried blood spot
• Critical congenital heart disease (CCHD)
• Urinalysis
• Hearing screening test

Among these methods, dried blood spot testing has received more attention due to the use of tandem mass spectrometry. This technique requires labeled compounds used as an internal standard in screening kits.