Microlissencephaly-micromelia syndrome is a syndrome of abnormal cortical development, characterized by severe prenatal polyhydramnios, postnatal microcephaly, lissencephaly, upper limb micromelia, dysmorphic facies (coarse face, hypertrichosis, and short nose with long philtrum), intractable seizures, and early death. Hypoparathyroidism was noted in one case.

In the resting position, the tip of the thumb is on, or near, the palm, close to the base of the fourth or fifth finger.