The Newborn Screening Programme

Question 1

In what year was the first case of PKU diagnosed?

Answer 1

1934

Question 2

Why is it important to diagnose PKU before the infants become ill?

Answer 2

Because once the infant is affected by the condition PKU can result in irreversible brain damage and mental retardation.

Question 3

What is the incidence of PKU?

Answer 3

approximately 1 in 10,000

Question 4

Is PKU evident in new borns?

Answer 4

No, they are protected by placental transfer and is therefore not evident in newborns.

Question 5

What was the concept of the original Guthrie test for PKU?

Answer 5

A blood spot was taken on filter paper and then sent off and incubated on agar with a bacteria that require phenyl alanine to grow. Only the samples from babies with PKU would result in growth of the bacteria.

Question 6

When did PKU screening begin in most places in the UK?

Answer 6

1969

Question 7

What happens when patients with PKU are treated?

Answer 7

They usually develop normally.

Question 8

What is one of the main things involved in PKU treatment?

Answer 8

A special diet.

Question 9

What is a benefit of PKU screening other than those for the individual and family?

Answer 9

Cost saving of these individuals not having to go into full time institutional care.

Question 10

What kind of problems can arise in screening programs? Illustrate these problems using the neuroblastoma screening programme as an example.

Answer 10

The Neuroblastoma story:

• Incidence of clinically detected disease is 1 in 29,000.
• When detected <1yrs at stage I, II or IV the prognosis is much improved.
• In 1985 it became possible to screen by measuring HVA and VMA in urine at 6 months, this was taken up in Japan and Newcastle.
• Survival in the screened population was >90% compared with 50% in clinically detected cases.
• However, after the introduction of screening the mortality rate due to neuroblastoma did not decline. This was due to 2 factors:
  1) . Poor sensitivity for cases that would go onto progress to clinically significant disease.
  2) . Screening was differentially picking up tumours that are least likely to progress and may spontaneously resolve.

Failed because the natural history of the condition was not understood well enough.

Not discontinued until 2004 - once you start screening it is very difficult to stop.

Net effect of the whole programme was that we had the just as many people dying, but in addition we had children being injured on the operating table.