Unusually high prevalence of cervical ribs in an 18th-Century Hungarian town: The impact of a tuberculosis epidemic.

Tuberculosis (TB) ravaged the Hungarian town of Vác in the 18th century. Nearly all of the young and middle-aged adults buried in the Dominican Church were infected with TB. Therefore, most women were likely infected with Mycobacterium tuberculosis (MTB) during pregnancy. In rodents, disruptions in early gestation, when the head-to-tail patterning of the embryo occurs, often result in an increased incidence of cervical ribs. Because TB severely disrupts pregnancy, we hypothesized that these disruptions would result in an increased number of cervical ribs in Vác residents. We examined 58 skeletons and found, as predicted, that the incidence of cervical ribs is exceptionally high in this population. Cervical ribs are approximately twenty-five times more common than in the healthy general population and shifts of the thoracolumbar boundary two to five times more common. Cervical ribs are usually associated with other congenital anomalies, including other homeotic vertebral transformations. Homeotic transformations at different vertebral boundaries were usually in the same direction and sometimes involved three boundaries. This implies a prolonged disruption of pregnancy and alterations in multiple Hox gene expression domains. Our study emphasizes that a high incidence of cervical ribs indicates vulnerability. Our data support the idea that cervical ribs can be induced not only by genetic changes, but also by infectious diseases and thus by environmental perturbations of pregnancy.