LOG-LINEAR ALLOMETRY OF FETAL CRANIOFACIAL GROWTH IN DOWNS-SYNDROME

Trisomy 21 develops as a result of nondisjunction of two homologous ch romosomes during either the first or second meiotic division. One of t he more important consequences of these genetic alterations is the pre dictable, although variable disturbance in the architecture of the cra niofacial region [1]. postnatal craniofacial morphology has been exten sively studied in Down's syndrome (DS). However, little information is available on human prenatal development of the head and face in such patients. The time at which changes in craniofacial phenotype first em erge in Down's syndrome fetuses and at which physical growth begins to diverge from normal is unknown. To explore these questions, we compar ed prenatal craniofacial growth in 50 Down's syndrome fetuses with tha t of 555 fetuses judged to be ''typical for body weight and age'' usin g the method of log-linear allometry [2].