Basically the study is a pilot to demonstrate that it is (or is not) possible to use neonatal Guthrie blood spots both for genotyping and separately immunological measures of infection contact. The ultimate aim is to study the relevance of (host resistance) genetic variation in the child (I know of the work on mannose binding lectin (MBL) in ALSPAC) but also immunological evidence in the child of specific infection contact during pregnancy (largely acquired by passive transfer of antibody from the mother, thoughherinfection contact may not have been during the pregnancy necessarily) for the occurrence of childhood tumours, particularly leukaemias.

In the absence of any really large centralised childhood biobanks in the UK of tissues other than neonatal blood spots (which exist in many discrete centres back to the 1980s) that could be used unambiguously to assess infection contact prior to childhood cancer diagnosis, it seems worthwhile to see whether it is technically feasible to make immunological measures in old blood spots.We know already that old blood spots (and other tissue samples) can be used reliably with amplification if necessary, to obtain DNA in sufficient quantities and quality for genotyping polymorphisms of interest (e.g. MBL, HLA).There are several reports also that it is possible to measure immunoglobulin evidence of specific infection contact, but we need to establish thoroughly whether we can do it reliably and in a multiplex way for several infections simultaneously given the everyday conditions of storage and availability of NHS blood spots.We will also need to

check those measures separately in maternal pregnancy sera, cord blood and perhaps childhood sera to demonstrate we can do it well, and the ALSPAC sample availability means this is possible.If we can demonstrate feasibility of such measurement, Scotland (which has stored centrally in one place blood spots for all children screened since 1968, and amongst whose childhood population we can identify about 3-4,000 cases of cancer) would be the place to carry out the definitive study, I think.

I have spoken to Dr Helena Kemp, Consultant Chemical Pathologist at North Bristol NHS Trust, and established that she holds easily retrievable blood spots for the Avon population born since about 1986, so the ALSPAC children should be included.With suitable permissions (I am not sure what ALSPAC families consented to) we could record-link ALSPAC to the NRCT here to define all childhood cancers in your cohort.I don't think this is intrinsically hugely interesting because there should only be about 30 cases, but power not withstanding, we should be able to use that event determination for other purposes also e.g. to study birthweight, growth and growth factors and risk, at least in a pilot sense.The meagre numbers also mean that it is unlikely anybody else will be particularly interested in childhood cancer in the ALSPAC cohort, so consumption of tissue for these kids and a small number of controls is unlikely to queer anybody else's future pitch.

We would like to use the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort in Bristol as the source material of choice in the pilot study. 14,541 pregnant women with a delivery date in 1991-92 were enrolled, and for many of those offspring in whom childhood leukaemia or other cancers were diagnosed, this will already be known to you, but we would propose to record link the cohort to the NRCT to determine fully the 30 or so malignancies (10 leukaemia, 20 other) the cohort of babies will have experienced by age 14. There is an abundance of other children to act as controls, and we propose concentrating on the 10 leukaemias, 20 other cases and 30 controls in this pilot study. For most women and children in the cohort there exists a maternal blood sample taken antenatally (gestation varies) and cord blood for the babies (and placenta/cord tissue sample). In addition though not directly relevant to us there is blood from each child who was followed at age 7 and blood on a 10% sample of the children for each of the first 5 years. The Guthrie blood spots for each child will have been obtained and stored separately by the Health Authority (Dr Kemp), rather than the ALSPAC team. Because the Guthrie spots might be a precious resource, undertaking the study in the ALSPAC cohort diminishes the force of the argument against consuming (part of) them in this way, because, unusually, similar tissue samples are known to exist for the same babies in the ALSPAC study if they were needed by others (and ALSPAC precious resources are unlikely to be wasted because few would want to focus particularly on the childhood cancer cases when the numbers in the cohort are so few, outside of a pilot study of the sort we propose). We would hope to obtain access in ALSPAC to the maternal antenatal blood, the baby's cord blood, and separately, (part of) the stored Guthrie samples. We would develop a method for immunological measurements in the blood spots (to be correlated with the maternal antenatal blood and foetal cord blood estimations) for one control infection (rubella) and one or two infections that might have occurred prenatally (or before the pregnancy) and be relevant to childhood leukaemia.

As prototype examples we would probably choose Influenza (many women will have been exposed in the 1989/90 epidemic, though 1991 and 1992 were relatively quiet flu years) and Epstein Barr virus, since significant frequency of recrudescence of this infection during pregnancy has now been linked twice to ALL risk and EBV is a plausible candidate infection for increasing risk.

The aim of the study is simply to demonstrate that for candidate infections of interest, markers of contact can be estimated in blood spots, which faithfully reflect other measures of contact by the mother before or during the pregnancy.If the ALSPAC team is happy to consider this request for a collaborative pilot study using your samples, I would be grateful if you could remind me of any costs that might need to be anticipated for use of data/samples on about one hundred children.