Patterns of pregnancy loss, perinatal mortality, and postneonatal childhood deaths in families of girls with Rett syndrome.

Rett syndrome is a neurodevelopmental disorder that occurs predominantly in girls and results in severe physical and intellectual handicap. A popular genetic mechanism is an X-linked dominant disorder, lethal in males. A case control study design was used to investigate fetal wastage as indicated by reported miscarriage and stillbirth prevalence, and the prevalence and cause of reported neonatal and other childhood deaths. There was no disturbance in the sibling sex ratio when case and control families were compared. In the parental generation and in the proband generation miscarriages were reported in similar proportions in case and control families. The reported stillbirth rates in case families was almost double that in control families and reported perinatal loss was more common on the maternal side in case families than in control families. Stillbirths and neonatal deaths affected slightly more boys in the parental and proband generations of case families (19 of 30) than in control families (10 of 21). Childhood deaths also occurred a little more commonly in Rett syndrome families. Sudden infant death syndrome was reported in three siblings of Rett syndrome probands but in no control siblings. Confirmation of this pattern of perinatal loss and infant mortality could indicate an alternative expression of the Rett syndrome gene.