Kari and Ed Lennon's daughter Addison and son Brooks were both born with Microcephaly with Seizures (MCSZ), an extremely unusual form of microcephaly in which the brain is of smaller size but is otherwise structurally normal. The Lennons headed to a clinic that specialized in hereditary forms of microcephaly. The clinic team, which was led by Christopher Walsh, MD, PhD, and included Edward Gilmore, MD, discovered MCSZ only two years prior. The Lennons' MCSZ, so rare, could only be detected by studying large families with shared ancestry on the other side of the world. One of the two MCSZ mutations that Addison and Brooks each carried had been previously identified in the Walsh lab's studies of Middle Eastern families.