Some scientists say that LB1 is merely a short modern human with a brain disorder called microcephaly.

Commonly, the fore-brain fails to divide into lobes or hemispheres (holoprosencephaly), and the entire head is unusually small (microcephaly).

Inadequate growth of brain: Microcephaly (abnormal smallness of head), and hydrocephalus (abnormal buildup of cerebrospinal fluid in the head).

They also have unusual facial features, poor muscle tone (hypotonia), small head size (microcephaly), and mental retardation.

Infants with cri du chat also typically have low birth weight, slow growth, a small head (microcephaly), and poor muscle tone (hypotonia).

Microcephaly (small head size) is common.

The opposite condition, microcephaly, may be caused by failure of the brain to develop or by intrauterine infection, drug toxicity, or brain trauma.