ESPE Abstracts

Background: In recent years more and more genetic defects along the GHRH–GH–IGF-I axis have been reported. Those mutations of the IGF-I receptor (R) are a rare abnormality of whom only the heterozygotes progenies survive.

Objective and hypotheses: To determine the birth length, weight and brain size using head circumference and find out whether these correlate with the type of mutation.

Method: Collection of data of 65 neonates from published literature.

Results: Forty-seven different mutations of the IGF-I (R) located on chromosome 15 have been identified. Birth length (BL), available for 28 neonates with a gestational age of 34–41 weeks, ranged between 39 and 49 cm (m±S.D.=45±2.7 cm), one was premature (30 cm at 31 weeks). Birth weight (BW) of 38 neonates ranged from 1400 cm to 2600 g (m±S.D.=2535±651 g). Two premature neonates weighed 650 950 g. The BW correlated with gestational age, not so the BL. The BMI of 27 neonates ranged from 6 to 13. Seven out of 16 mothers were short (133–148 cm). There was no correlation between type of mutation and birth length or weight. In 21 records microcephaly was ascertained or stated.

Conclusion: Heterozygotes neonates for a variety of IGF-I-R mutations tend to be shorter and more microcephalic than neonates with hGH gene deletions and GH-R defects, (Laron syndrome). They are also less obese than the above diagnostic entities. The below normal head circumference indicates the important role of IGF-I in the intrauterine growth of the brain in addition to that on linear growth.