Guidance

Appendix A: incidence and positive predictive values

Updated 23 April 2025

The table below shows the approximate UK incidence and positive predictive value of each condition.

The positive predictive value (PPV) is the likelihood that a baby with a screen positive result will have the condition. This varies with each condition.

Condition UK incidence PPV% Without early treatment, the condition can result in
SCD 1 in 2,800 95% severe pain, life threatening infections and anaemia (symptoms can be present even with treatment)
CF 1 in 2,500 70% poor weight gain, frequent chest infections and reduced life expectancy (symptoms can be present even with treatment)
CHT 1 in 2,000 70% permanent, serious physical problems and learning disabilities
PKU 1 in 10,000 80 to 90% permanent brain damage and serious learning disabilities
MCADD 1 in 10,000 80 to 90% serious illness, coma and possible death
MSUD 1 in 150,000 50% coma, permanent brain damage and possible death
IVA 1 in 150,000 50% coma, permanent brain damage and possible death
GA1 1 in 300,000 50% coma and brain damage which affects muscle movement
HCU 1 in 300,000 50% learning difficulties, eye problems, osteoporosis, blood clots or strokes