FACTORS IN LIFESTYLES OR ENVIRONMENT

One study has reported an association between low socioeconomics status and holo-prosencephaly risk. However, this observation has not been confirmed.

A case-control study found a suggestion of an association between cytogenetically normal holo-prosencephaly and maternal alcohol consumption during early pregnancy. Maternal smoking, respiratory illness medications, and salicylate-containing medication have also shown tera-togenic effects (Coren 2000). However, some of these associations were not statistically significant. Another study reported no significant link between alcohol, smoking, or x-ray exposure and holo-prosencephaly risk (Cohen 1989). An investigation failed identifies any significant association between holo-prosencephaly and proximity to various types of industry (Castilla 2000).

Maternal diabetes has been reported by several studies to increase holo-prosencephaly (Becerra 1990). It should be noticed that diabetes causes a series of metabolic disturbances, and these disturbances interfere with fetal development. Other metabolic disturbances, including cholesterol production, can affect the sonic Hedgehog (Shh) signaling pathway (Cohen 2002).

Other maternal factors that have been tentatively associated with holo-prosencephaly, based on anecdotal evidence or studies involving small numbers of cases, include retinoic acid, salicylate, estrogen/progestin, anticonvulsant, weight reduction diets and/or low maternal weight, previous pregnancy loss, and congenital infection with cytomegalovirus, rubella, and toxoplasmosis (Croen 1996).  One survey that involved a small number of cases failed to identify any association between holo-prosencephaly and retinoic acid (De Wals 1991). A case-control study suggests that risk of holo-prosencephaly may be increased with maternal use of misoprostol, a synthetic prostaglandin used for elective termination (Orioli 2000).

There is no information available about the use of multivitamins and folic acid to reduce the incidence of holo-prosencephaly (Czeizel 2004). Maternal residence and vicinity to solid waste incinerators or landfills does not increase the incidence of holo-prosencephaly (Cordier 2004), nor does maternal exposure to pesticides (Berkowitz 2003), biological solvents (Wennborg 2005), or marijuana (Fried 2000).

Prevalence

Birth prevalence in the United States for hypo-plastic left heart syndrome is no currently known. The rate in Texas for 1999-2002 deliveries was 1.21 cases per 10,000 live births (Texas Department of State Health Services 2005). Differences in prevalence may be due to differences in case inclusion criteria.