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What is microcephaly?

Microcephaly is a medical condition in which the circumference of the head is small because the brain has not fully developed or has stopped growing. Microcephaly can be present at birth or it may develop in the first few years of life. It is most often caused by genetic abnormalities that interfere with the growth of the cerebral cortex during the early months of fetal development. Babies may also be born with microcephaly if, during pregnancy, their mother:

  • Abused drugs or alcohol
  • Became infected with a cytomegalovirus, rubella (German measles), varicella (chicken pox) virus, or possibly zika virus
  • Was exposed to certain toxic chemicals
  • Had untreated phenylketonuria (PKU), a harmful buildup of the amino acid phenylalanine in the blood

Microcephaly is associated with Down's syndrome, chromosomal syndromes, and neurometabolic syndromes. With viral-induced brain injury there is often widespread tissue and cell death leading to brain shrinkage rather than simply impaired growth.

Depending on the severity of the accompanying syndrome, children with microcephaly may have:

  • Impaired cognitive development
  • Delayed motor functions and speech
  • Facial distortions
  • Dwarfism or short stature
  • Hyperactivity
  • Seizures
  • Difficulties with coordination and balance
  • Other brain or neurological abnormalities
Learn About Clinical Trials
Clinical trials are studies that allow us to learn more about disorders and improve care. They can help connect patients with new and upcoming treatment options.

How can I or my loved one help improve care for people with microcephaly?

Consider participating in a clinical trial so clinicians and scientists can learn more about microcephaly and related disorders. Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.

All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with microcephaly at Clinicaltrials.gov.

Where can I find more information about microcephaly?

More information about microcephaly may be available from the following resources:

Order publications from the NINDS Catalog
The NINDS Publication Catalog offers printed materials on neurological disorders for patients, health professionals, and the general public. All materials are free of charge, and a downloadable PDF version is also available for most publications.