Is the response to growth hormone in short children born small for gestational age dependent on genetic or maternal factors?

BACKGROUND/AIMS We investigated whether genetic or maternal/environmental risk factors for being born small for gestational age (SGA), e.g. Silver-Russell syndrome, congenital heart defects, infections of mothers or smoking during pregnancy, explain the variation in the first-year growth response to GH therapy. METHODS Secondary analysis was made of growth response in 135 short prepubertal German children (66% males) enrolled in a SGA phase III trial. Initial mean patient age was 6.8 +/- 2.6 years; mean patient height SDS -3.8 +/- 1.2, and GH treatment dose was 0.066 mg/kg body weight per day. RESULTS Growth velocity increased by 4.5 +/- 2.0 cm/year and height SDS by 1.0 +/- 0.5 SDS. Although patient number was limited and variation was high, both growth response (cm/year) and change in height SDS did not appear to differ between subgroups which also did not differ in terms of Studentized residuals set up in the KIGS growth prediction model for SGA. Likewise, in a step-forward multivariate analysis, the variables Silver-Russell syndrome, congenital heart defects, infections of mothers and smoking were not identified as independent factors influencing growth velocity. CONCLUSION The retrospectively analyzed genetic and maternal/environmental risk factors for SGA do not appear to explain the observed patient variance in response to GH. Larger prospective studies are needed, however, to substantiate these preliminary findings.