The following disorders are currently in the screening programme:

Thyroid disorder

• Congenital hypothyroidism (CH): group of disorders in which the thyroid gland produces insufficient amounts of thyroid hormone (thyroxine, T4). CH is usually permanent and usually not hereditary. T4 plays an important role in regulating metabolism and is essential for growth and development. T4 deficiency at a young age has a negative impact on brain development, with a risk of permanent learning disability and limited motor ability. Early treatment with T4 can prevent this (almost) entirely. Treatment: lifelong course of daily thyroxine tablets. Prevalence: about 70-90 children per year.

Adrenal disorder

•  Adrenogenital syndrome (AGS): life-threatening, hereditary disorder affecting hormone production by the adrenal glands. The deviation leads to a cortisol deficiency, often also an aldosterone deficiency and an overproduction of androgens. In newborns, excessive salt loss leads to dehydration. At birth, girls have different degrees of masculinisation of the external genitals. Early treatment can prevent serious disruption of water and salt metabolism. Treatment: lifelong course of corticosteroid medication and other complementary medication. Prevalence: about 10-15 children per year.

Metabolic disorders (MZ)

• Adrenoleukodystrophy (ALD) (from 1 October 2023): an X-linked hereditary metabolic disorder characterized by a malfunctioning ALD enzyme (protein) in the body. This enzyme deficiency leads to an inability to properly break down certain fats, known as very long-chain fatty acids. Consequently, these fats accumulate within the body. In boys and men this can cause significant damage to the adrenal gland, spinal cord and brain. The specific symptoms can vary among affected boys. Women with ALD develop a different, generally milder form of ALD. This form manifests at an older age (40-60 years) and is not treatable in adulthood. For that reason, only male newborns are tested for ALD. Treatment options for ALD include stem cell transplantation and hormone replacement. Prevalence of ALD: estimated at around 5-10 male newborns per year.

• Biotinidase deficiency (BIO): hereditary metabolic disorder in which too little biotin (vitamin H) is produced. Untreated it results in skin problems, epileptic attacks, occasional baldness (partial or complete), delayed development and muscle problems. Early treatment can prevent all symptoms. Treatment: lifelong course of biotin. Prevalence: about 2-4 children per year.

• Galactosaemia (GAL): hereditary metabolic disorder in which galactose (component of milk sugar, also known as lactose) is not broken down sufficiently. Lactose is found in breast milk and in many food products for infants. Leads to severe jaundice, infection, cataracts (an eye disease) and death. Despite good treatment, galactosemia might lead to developmental delay and reduced fertility in of girls. Treatment: strict lifelong diet low in galactose. Prevalence: about 2-4 children per year.
• Glutaric acidaemia type I (GA-I): hereditary metabolic disorder, in which the amino acids lysine and tryptophan are not broken down properly. Untreated, this can lead to brain damage. A diet and medicinal treatment can prevent brain damage. Treatment: lifelong dietary protein restriction, with ‘amino acid preparation’ and medication. Prevalence: about 1 child per year.
• HMG-CoA-lyase deficiency (HMG): hereditary metabolic disorder in which the amino acid leucine is not broken down properly, resulting in suboptimal fatty acid oxidation leading to an energy deficiency. Problems arise during fasting, overnight sleeping, operations, periods of diarrhea and vomiting. If left untreated, the disease can cause vomiting, weakness and drowsiness, loss of consciousness, neurological problems and impaired development. Treatment: sometimes medication (carnitine) and a diet. Prevalence: about 1 child every 10 years.
• Isovalerian acidity (IVA): hereditary metabolic disorder in which the amino acid leucine is not broken down properly. Leads to vomiting, loss of consciousness, severe developmental retardation and death. Treatment: lifelong dietary protein restriction, ‘amino acid preparation’ and medication. Prevalence: about 2 children per year.
• Maple syrup urine disease (MSUD): hereditary metabolic disorder in which the breakdown of the amino acids leucine, isoleucine and valine is impaired. Untreated, the urine of the child and the child itself smell sweet. Lack of timely treatment leads to vomiting, loss of consciousness, severe developmental retardation and death. Treatment: lifelong protein-poor diet and an ‘amino acid preparation’. Prevalence: about 1 child every two years.
• Phenylketonuria (PKU): hereditary metabolic disorder in which the amino acid phenylalanine is not broken down. Leads to severe developmental retardation. Treatment: lifelong strict dietary protein restriction, with ‘amino acid preparation’. In some cases medication is prescribed. Prevalence: about 12-15 children per year.
• 3-Methylcrotonyl-CoA carboxylase deficiency (3MCC deficiency): hereditary metabolic disorder in which certain proteins containing the amino acid leucine are not broken down sufficiently. Can lead to convulsions, developmental retardation and loss of consciousness. Most children only have symptoms when they are ill. Treatment: dietary advice during illness. In some cases, lifelong dietary protein restriction and medicines is needed. . Prevalence: about 1-2 children per year.
• Tyrosinaemia type 1 (TYR-1): hereditary metabolic disorder in which the amino acid tyrosine is not broken down properly. Can lead to liver failure, kidney problems, nerve disorders, liver cancer and death. Treatment: lifelong strict protein restriction, amino acid supplements and medication. Sometimes, liver transplantation is necessary. Prevalence: about one child per year.
• Multiple CoA carboxylase deficiency (MCD): hereditary metabolic disorder in which proteins in the diet can not be properly converted into useful substances. Can lead to dehydration, loss of consciousness, skin abnormality, baldness, neurological problems, epileptic attacks and immune system defects. Treatment: lifelong administration of vitamin H, sometimes supplemented with dietary protein restriction (or moderate dietary protein restriction). Prevalence: very rare.
• Long-chain 3-hydroxyacyl-coenzyme a dehydrogenase deficiency (LCHADD): hereditary metabolic disorder in which long-chain fatty acids cannot be used as an energy source. Problems arise during fasting, overnight sleeping, operations, periods of diarrhoea and vomiting. The low blood sugar level may lead to sleepiness, drowsiness and loss of consciousness, and to muscle problems and cardiac muscle problems. Treatment: prevent that patients do not go for too long without eating, tight mealtime schedule, diet that includes extra carbohydrates and special fats. Prevalence: about 1 child per year.
• Medium-chain acyl-CoA dehydrogenase deficiency (MCADD): hereditary metabolic disorder in which medium-chain fatty acids cannot be used as an energy source. Problems arise during fasting, overnight sleeping, operations, periods of diarrhoea and vomiting. The low blood sugar level may lead to sleepiness, drowsiness, loss of consciousness finally resulting in death. Treatment: ensure that patients do not go for too long without eating. Sometimes extra nutrition and medication is needed. Prevalence: about 10-15 children per year.
• Very long-chain acyl-coenzyme A dehydrogenase deficiency (VLCADD): hereditary metabolic disorder in which very long-chain fatty acids cannot be used for energy. Problems arise during fasting, overnight sleeping, operations, periods of diarrhoea and vomiting. The low blood sugar level may lead to sleepiness, drowsiness, loss of consciousness finally resulting in death. Treatment: prevent that patients do not go for too long without eating, tight mealtime schedule, diet that includes extra carbohydrates and special fats. Prevalence: about 2-4 children per year.

Blood disorders:

• Sickle cell anaemia (SZ): hereditary haemoglobin abnormality; at low oxygen tension, this leads to abnormally shaped red blood cells, which may clog small capillaries. This results in severe bone pain and organ infarctions (cerebral infarction and pulmonary infarction), plus an increased chance of serious infections, as the spleen does not work properly. The accelerated breakdown of blood results in anaemia. Treatment: analgesics, extra fluids and antibiotics. Blood transfusions may occasionally be required. Prevalence: about 35 children per year.
  Screening for sickle cell anaemia can also detect carrier status for this disease. The parents are informed, if they so wish (affects an average of 850 children per year).
• Alfa-thalassemia (HbH): hereditary disorder in which insufficient alpha-globin chains are produced. Children suffer from medium anaemia directly after birth. Treatment: folic acid supplements, blood transfusion. In case a patient is dependent on blood transfusions, stem cells transfusion can be considered. Prevalence: about 1 child per 2 years. 
• Bèta-thalassemia major: hereditary disorder in which none or insufficient beta-globin chains are produced. From the third month after birth, progressive severe anemia will arise, which can be life threatening. Treatment: chronical blood transfusion and deferrization, daily folic acid supplements. In case a patient is dependent on blood transfusions, stem cell transfusion can be considered. Prevelance: about 2-5 children each year.

Pulmonary disorder:

• Cystic Fibrosis (CF): hereditary disorder in which mucus that is thicker and stickier than normal is produced in various parts of the body. The thick and sticky mucus causes problems in the airways and gastrointestinal tract. Early treatment can help to prevent or diminish these problems. Treatment: medication, caloric diet and physiotherapy. Prevalence: about 30-35 children per year.

Immune disorder:

• Severe combined immunodeficiency (SCID): a serious, rare disease of the immune system. SCID prevents immune cells from developing properly, leading to infections in areas such as the lungs, the gastrointestinal tract and the skin. Infections usually start in the first few months of life. Infections that are not usually dangerous can be life threatening for children with SCID. Without treatment, children with SCID can die in the first year of life. Treatment: stem cell transplantation, and avoiding infections until this time. Prevalence: about 2 to 4 children per year.

Muscle disorder:

• Spinal muscular atrophy (SMA), from 1 June 2022: hereditary disorder. Children get paralysed and can die from it. Complaints usually start at an early age. The seriousness of the disease varies per child. Early detection of SMA means that treatment can start within a few weeks after birth. This prevents irreparable damage and severe suffering. Prevalence: about 15-20 children per year.