Utilized to screen for selected metabolic, endocrine, hematologic and functional disorders.
For presymtomatic identification of serious conditions for which effective treatment exists.
Substantial variation exists from state to state in the number of disorders included in such screenings.
Presently 32 disorders are recommended for screening.
Newborn screening (NBS) refers to the screening in infants shortly after birth for conditions that are treatable, but not clinically evident in the newborn period.
The goal is to identify infants at risk for these conditions early enough to confirm the diagnosis and provide intervention that will alter the clinical course of the disease and prevent or ameliorate the clinical manifestations.
NBS started with the discovery that the amino acid disorder phenylketonuria (PKU).
PKU could be treated by dietary adjustment, and that early intervention was required for the best outcome.
Infants with PKU appear normal at birth, but are unable to metabolize the essential amino acid phenylalanine, resulting in irreversible intellectual disability.
Screening programs are often run by state or national governing bodies with the goal of screening all infants born in the jurisdiction for a defined panel of treatable disorders.
Most NBS tests are done by measuring metabolites or enzyme activity in whole blood samples.
Bedside tests for hearing loss via automated auditory brainstem response and congenital heart defects using pulse oximetry are included in some NBS programs.
Infants who screen positive undergo further testing.
Let me provide a comprehensive list of common newborn screening tests. Since this is medical information that parents and healthcare providers rely on, I’ll focus on the core testing panel while noting that specific tests can vary by location and healthcare system.
Common newborn screening tests include:
Metabolic Disorders: – Phenylketonuria (PKU) – Maple Syrup Urine Disease (MSUD) – Galactosemia – Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) – Very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) – Isovaleric acidemia – Glutaric acidemia type 1
Endocrine Disorders: – Congenital hypothyroidism – Congenital adrenal hyperplasia (CAH)
Blood Disorders: – Sickle cell disease – Various hemoglobinopathies – G6PD deficiency
Other Critical Conditions: – Cystic fibrosis – Severe combined immunodeficiency (SCID) – Critical congenital heart disease (pulse oximetry screening) – Biotinidase deficiency – Hearing loss
Duchenne muscular dystrophy is a disease that has been added to screening programs in several jurisdictions around the world, despite the lack of evidence as to whether early detection improves the clinical outcome for a patient.
Worldwide, it is estimated that 7% of the population may carry a hemoglobinopathy with clinical significance.
The most well known condition in this group is sickle cell disease.
Urea cycle disorders Disorders of the distal urea cycle, such as citrullinemia, argininosuccinic aciduria and argininemia are included in newborn screening programs in many jurisdictions that using tandem mass spectrometry to identify key amino acids.
Lysosomal storage disorders are not included in newborn screening programs with high frequency.
Undiagnosed hearing loss in a child can have serious effects on many developmental areas, including language, social interactions, emotions, cognitive ability, academic performance and vocational skills, any combination of which can have negative impacts on the quality of life.
The serious impacts of a late diagnosis, combined with the high incidence (estimated at 1 – 3 per 1000 live births, and as high as 4% for neonatal intensive care unit patients) have been the driving forces behind screening programs designed to identify infants with hearing loss as early as possible.
Newborn hearing testing is done at the bedside using transiently evoked otoacoustic emissions, automated auditory brainstem responses, or a combination of both techniques.
In some cases, critical congenital heart defects (CCHD) are not identified by prenatal ultrasound or postnatal physical examination.
Pulse oximetry has been recently added as a bedside screening test for CCHD at 24 to 48 hours after birth.
Severe combined immunodeficiency (SCID) caused by T-cell deficiency is a disorder that was recently added to newborn screening programs.
Duchenne muscular dystrophy (DMD) is an X-linked disorder caused by defective production of dystrophin.
Many jurisdictions around the world have screened for, or attempted to screen for DMD.
Newborn screening samples are collected from the infant between 24 hours and 7 days after birth.
As of 2023, numerous initiatives using next generation sequencing (NGS) have been announced worldwide including the Genomic Uniform-screening Against Rare Diseases in All Newborns.
California now mandates newborn screening for all infants and tests for 80 congenital and genetic disorders.