Achalasia-microcephaly syndrome is an extremely rare genetic condition that has been reported in only a few families. It is marked by a small head size (microcephaly), intellectual challenges, and problems with the esophagus known as achalasia. Achalasia can cause difficulties in swallowing, coughing, vomiting, and may lead to failure to thrive, especially in infancy or early childhood. The syndrome is inherited in an autosomal recessive pattern, meaning that a child may need to receive one copy of the gene from each parent to develop the condition. In one reported case, exposure to the drug Mefloquine during pregnancy was noted, though this has not been established as a common risk factor. Information about the wider population impact is limited given the very small number of documented cases.

Common symptoms in people with achalasia-microcephaly syndrome include a small head size, difficulties with intellectual development, and signs related to achalasia. Achalasia symptoms may include coughing, trouble swallowing, vomiting, failure to gain weight, and a risk of food or liquid going into the lungs (aspiration) in infancy or early childhood.

This syndrome appears to have a genetic cause with an autosomal recessive pattern of inheritance. There is also a report of antenatal exposure to Mefloquine in one unique case, but this is not yet clearly established as a common cause. Further research is needed to fully understand the underlying causes of this condition.