Stimmler syndrome is a rare condition that has been reported in only two cases. It is characterized by a combination of features including a smaller head size (microcephaly), low birth weight, and severe intellectual deficits. Other notable characteristics include dwarfism, small teeth, and the development of diabetes mellitus. Biochemical tests in people with this condition show high levels of alanine in the urine and raised levels of alanine, pyruvate, and lactate in the blood. This overview is based on the limited information available. Because so few cases have been described, understanding of the condition is still in the early stages. The condition is known by several names, which all refer to the same clinical findings of alaninuria with microcephaly, dwarfism, enamel hypoplasia, and diabetes mellitus.

People with Stimmler syndrome have been observed to have several signs including microcephaly (a smaller head size), low birth weight, significant intellectual challenges, dwarfism (short stature), small teeth, and diabetes mellitus. The consistent biochemical marker noted is high alanine in the urine along with elevated levels of alanine, pyruvate, and lactate in the blood.

The exact cause of Stimmler syndrome is not fully understood. Biochemical tests reveal abnormal levels of certain substances in the body, such as elevated alanine, which suggests a disturbance in normal metabolism. There are no known gene mutations or genetic markers clearly linked to the condition at this time.