- Autosomal recessive malignant osteopetrosis (MOP) is a lethal disease, unless bone marrow is successfully transplanted. Yet a donor may not always be available, and even when there is one transplantation results are far from optimal. The difficulty in obtaining conclusive results by sonographic and X-ray evaluation of the fetus makes prenatal molecular diagnosis highly desirable. Subsequent to the chromosomal localization of the MOP gene in Arab-Bedouin families from the Negev region in Israel, linkage analysis was used for the prenatal diagnosis of this disease in Bedouin families at risk. Twelve cases were diagnosed, three fetuses were found to be affected, and one of the pregnancies was terminated. The other two pregnancies continued to term and the diagnosis of osteopetrosis was confirmed by X-ray immediately after birth. This is the first report on prenatal diagnosis of autosomal recessive osteopetrosis by linkage analysis. Copyright © 2001 John Wiley & Sons, Ltd.