Ngā mate e kitea ana pea i te whakamātau poka rekereke Disorders screened for in the heel prick test (newborn blood spot screening)
All of the screened disorders are rare. They are usually inherited from one or both parents. Your first pēpi (baby) may not have a disorder, but you may have pēpi in the future who are born with a disorder. Different genetic conditions cause each disorder and affect important processes in the body.
About the disorders
Disorders can vary in:
- when they appear
- how severe they are
- how they are inherited.
Without treatment, screened disorders can range from mild to acute life-threatening.
Disorders screened for
Newborn screening tests for the following disorders:
- congenital hypothyroidism
- cystic fibrosis
- amino acid disorders
- fatty acid oxidation disorders
- congenital adrenal hyperplasia
- galactosaemia
- biotinidase deficiency
- severe combined immune deficiency
- spinal muscular atrophy from early 2025 (this will be updated once start date confirmed).
Sometimes new disorders are added to the screening programme, and others are removed.
Why disorders are removed
Disorders are removed where they no longer meet screening criteria, for example, new evidence was assessed by clinical experts and it was agreed that a disorder should no longer be screened. This may be:
- due to screening for that disorder having insufficient clinical benefit for the child
- if it was determined that the criteria for screening suitability were not being met due to a high number of false positive results, and lack of true cases detected.
Cause, treatment and frequency of screened disorders
The disorders, cause, treatment, and frequency for Aotearoa New Zealand.
Cause
The thyroid (a small, butterfly-shaped gland located at the base of the neck, just below the Adam's apple) is missing, formed in the wrong place, or is not working properly and does not produce enough thyroid hormone. This can lead to slow growth and developmental delay.
Treatment
Replacement thyroid hormone medicine.
Frequency
1 in 2,500 pēpi — about 25 a year.
Cause
A defective gene that makes the body produce abnormally thick and sticky fluid, called mucus. This mucus builds up in the breathing passages of the lungs and in the pancreas, leading to poor absorption of food, poor growth, susceptibility to chest infections and difficulty breathing.
Treatment
Medicine and physiotherapy.
Frequency
1 in 6,000 pēpi — about 10 a year.
Cause
An enzyme is missing, for example an enzyme (called phenylalanine hydroxylase) in phenylketonuria (PKU). Without this enzyme an amino acid (called phenylalanine) rises to harmful levels and can lead to developmental delay. Other amino acid disorders can lead to serious illness and death.
Treatment
Special diet.
Frequency
1 in 15,000 pēpi — about 4 a year.
Other amino acid disorders
- argininosuccinic aciduria (argininosuccinate lyase deficiency)
- citrullinaemia (argininosuccinate synthetase deficiency, citrin deficiency)
- glutaric acidaemia type I (glutaryl-CoA dehydrogenase deficiency)
- homocystinuria (cystathionine beta-synthase deficiency)
- isovaleric acidaemia (isovaleryl-CoA dehydrogenase deficiency)
- methylmalonic acidurias (mutase deficiency, CblA, CblB, CblC, CblD defects)
- propionic acidaemia (propionyl-CoA carboxylase deficiency)
- maple syrup urine disease (branched chain ketoacid dehydrogenase deficiency)
- tyrosinemia Type I.
Cause
An enzyme needed to break down fats is missing. Without these enzymes energy cannot be converted from fats. This can lead to episodes of low blood sugar, coma and death.
Treatment
Regular feeding, avoid fasting.
Frequency
1 in 10,000 pēpi — about 6 a year.
Other fatty acid disorders
- CACT (carnitine acylcarnitine translocase deficiency)
- CPT-I (carnitine palmitoyltransferase-I deficiency)
- CPT-II (carnitine palmitoyltransferase-II deficiency)
- LCHAD (3-hydroxy long-chain acyl-CoA dehydrogenase deficiency)
- TFP (trifunctional protein deficiency)
- MADD (multiple acyl-CoA dehydrogenase deficiency)
- MCAD (medium-chain acyl-CoA dehydrogenase deficiency)
- VLCAD (very-long-chain acyl-CoA dehydrogenase deficiency).
Cause
A missing enzyme in the adrenal gland (glands on top of both kidneys). In severe forms this leads to:
- A lack of hormone and salt loss that can lead to vomiting, dehydration and life-threatening collapse in the first weeks of life.
- External genitals that appear masculinized in biological females (ambiguous genitalia)
Treatment
Steriod medicines.
Frequency
1 in 25,000 pēpi — about 3 a year.
Cause
A defective enzyme prevents normal breakdown and use of milk sugar leading to:
- yellow skin or eyes (jaundice)
- blurry vision (cataracts)
- life threatening illness.
Treatment
Avoiding foods that contain lactose and galactose, such as dairy products.
Frequency
1 in 110,000 pēpi — about 1 every 2 years.
Cause
A missing enzyme resulting in a deficiency in vitamin H (biotin). This deficiency can lead to:
- seizures
- hearing loss
- developmental delay.
Treatment
Vitamin H (biotins).
Frequency
1 in 180,000 pēpi — about 1 every 3 years.
Cause
A lack of cells essential for immunity can lead to severe and life-threatening infections.
Treatment
Antibiotics, the need for protective isolation and bone marrow transplant.
Frequency
1 in 60,000 pēpi — about 1 a year.
Screening for this disorder is expected to start early 2025. Exact timeframes are still being worked through and this information will be updated when a start date has been set.
Cause
A missing or faulty gene called the SMN1 gene leading to loss of motor nerves in the spinal cord. This can lead to life threatening muscle weakness, difficulties in breathing and swallowing.
Treatment
Medicine (oral or spinal infusion) to preserve muscle and nerve function.
Frequency
1 in 10,000 pēpi — about 6 a year.