Israeli jewish infants of different descent: growth patterns, likeness and differences. Longitudinal study.

Background: Due to increasing migration process and intermarriages among individuals belonging to different ethnic groups, it is important to examine whether intermixing of populations effects child growth rate.

Aims: To compare growth patterns of Jewish infants from distinct descent.

Subjects: 1300 Israeli children were divided into 7 groups: 4 groups of babies with both parents from the same geographic origin (Europe, Yemen, Middle East or North Africa) and 3 inter-mixed groups according to genetic distances between the parents' derivation.

Study design: The studied infants were monitored longitudinally for both body length. weight and head circumference from birth until 20 months of life. Using the curve fitting technique the follow-up data were fitted to the 3-parameter Count model.

Outcome measurements: Three sets of maximal likelihood estimates of the model parameters were obtained to test the growth patterns of different groups of Jewish children: individually-specific for every child, group specific for each individual within the group, and general for all individuals from all studied groups. Likelihood ratio test was used to examine whether the chosen function of trait dependence on age is uniformly reliable for all individuals from all the considered groups.

Results and conclusions: Significant differences were indicated between all studied growth curves for all three studied traits. Moreover, distances calculated between the studied cohorts demonstrated a clear distinction between the clusters of "non-mixed" and "mixed" groups for length and weight. Since the studied children were born and developed in similar environments, these results may serve as important evidence for the existence of a genetic effect on the growth process.