Hennekam-Beemer syndrome is characterized by the association of skin mastocytosis (appearing as diffuse pigmentation), short stature, microcephaly, conductive hearing loss, and dysmorphic features. It has been described in only two (female) cases: one with normal mental development born to consanguineous parents and the other with severe psychomotor retardation born to unrelated parents. The mode of inheritance is most likely autosomal recessive.

Increased thickness of the lower lip, leading to a prominent appearance of the lower lip. The height of the vermilion of the lower lip in the midline is more than 2 SD above the mean. Alternatively, an apparently increased height of the vermilion of the lower lip in the frontal view (subjective).