The cranial malformations are the most apparent effects of acrocephalosyndactyly. Cranial synostosis occurs, as explained above, with Brachiocephaly being the common pattern of growth. Additionally, a common characteristic is a high, prominent forehead and a flat posterior skull. Due to the premature closing of sutures of the skull, increased cranial pressure develops which sometimes leads to mental deficiency. Nonetheless, this is not always the case since some of these people possess normal intelligence. Furthermore, a flat or concave face may develop because of a deficient growth in the mid-facial bones, leading to a condition known as pseudomandibular prognathism. Other features of acrocephalosyndactyly may be shallow bony orbits and broadly spaced eyes.
Low-set ears is also a typical characteristic, as is with all of these disorders that are called branchial arch syndromes. The reason for this is that in fetal life all ears are much lower than what we are accustomed to seeing. During normal development, the ears "travel" upward on the head but, in these cases, the ears do not follow this normal pattern of development since these syndromes have the greatest effects on the head.
The major attribute of this syndrome is syndactyly of the hands and feet. Commonly there is fusion of fingers or toes with usually an equal amount on both sides. It is usual for the middle 3 fingers to be fused together. This appearance is the characteristic for which acrocephalosyndactyly is named. The thumb and big toe may be broad and malformed. This disorder is progressive with age as the joints continue to appear present but are immovable.
