Microcephaly 20, Primary, Autosomal Recessive

Background and History: 

This is a recently described condition of abnormal brain development that results in external and internal malformations.

Clinical Correlations: 

Newborns have abnormally small heads and are 'floppy' with a decrease in muscle tone.  Older children are short in stature.  Generalized developmental delay and intellectual disability can be severe.  Speech is generally poor and some children are unable to speak at all.  Most never develop the ability to walk which can be complicated by foot deformities.  Behavior problems such as aggression, ADHD, as well as features of autism are common.

"Blindness" and underdeveloped optic nerves (that connect the eye to the brain) have been reported.  The eyes are smaller than normal.  Among the few children who underwent MRIs, various nonspecific developmental abnormalities were found in the brain.


Changes (mutations) in both members of a specific pair of genes are responsible for this condition.  There is a high rate of consanguinity among parental couples as well and these characteristics are consistent with autosomal recessive inheritance.  The parents, who are clinically normal, each carry one member of the mutated pair and transmit a 25% risk to each offspring to inherit both mutated members of the pair.

Diagnosis and Prognosis: 

The smaller than normal head likely will call attention to the presence of a developmental disorder but the specific condition is unlikely to be identified without gene mutation studies.  Pediatricians, neurologists, and geneticists are likely to collaborate in the diagnosis and care of these patients.

There is no known treatment specific for this condition but general supportive care is necessary.  Longevity may be shortened.

Additional Information
Autosomal recessive