[3] In general, life expectancy for individuals with microcephaly is reduced, and the prognosis for normal brain function is poor.

[11] As the child grows older, the smallness of the skull becomes more obvious, although the entire body also is often underweight and dwarfed.

These include mosquitoes, fleas, sand flies, lice, ticks, and mites that are hematophagous vectors.

[48][49][50][51] A study published in The New England Journal of Medicine has documented a case in which they found evidence of the Zika virus in the brain of a fetus that displayed the morphology of microcephaly.

Microlissencephaly is microcephaly combined with lissencephaly (smooth brain surface due to absent sulci and gyri).

[53][54][55] After the dropping of atomic bombs "Little Boy" on Hiroshima and "Fat Man" on Nagasaki, several women close to ground zero who had been pregnant at the time gave birth to children with microcephaly.

[56] Microcephaly was present in 7 children from a group of 11 pregnant women at 11–17 weeks of gestation who survived the blast at less than 1.2 km (0.75 mi) from ground zero.

[59] Microcephaly generally is due to the diminished size of the largest part of the human brain, the cerebral cortex, and the condition can arise during embryonic and fetal development due to insufficient neural stem cell proliferation, impaired or premature neurogenesis, the death of neural stem cells or neurons, or a combination of these factors.

For example, the Notch pathway genes regulate the balance between stem cell proliferation and neurogenesis in the stem cell layer known as the ventricular zone, and experimental mutations of many genes can cause microcephaly in mice,[61] similar to human microcephaly.

[citation needed] Microcephaly is a feature common to several different genetic disorders arising from a deficiency in the cellular DNA damage response.

[70] People with microcephaly were sometimes sold to freak shows in North America and Europe in the 19th and early 20th centuries, where they were known by the name "pinheads".

[72] Stars of the 1932 film Freaks were cited as influences on the development of the long-running comic strip character Zippy the Pinhead, created by Bill Griffith.