1. Starship Children's Hospital (N.L.H., C.J.), 1023 Auckland, New Zealand;
2. Liggins Institute (S.N.S., J.G.B.D., W.S.C., P.L.H.), 1142 Auckland, New Zealand;
3. New Zealand National Screening Unit (D.W., J.C.), Ministry of Health, 1051 Auckland, New Zealand
4. Department of Statistics (Y.J.), University of Auckland, 1142 Auckland, New Zealand;