Type II failure of differentiation/separation
Apert Syndrome is a genetic disorder characterized by the premature fusion of certain skull bones (craniosynostosis). This early fusion causes abnormal skull and facial growth that affects the shape of the head and face. Malformations are seen with the skull, face, hands and feet. During fetal development, there is no selective cell death causing the digits not to separate and the skull and facial bones to fuse too soon. (syndactyly)
Apert Syndrome is a rare autosomal dominant disorder caused by a genetic mutation of chromosome #10. If either parent has Apert Syndrome, there is a 50% chance of passing it to their child.
There are three types of symmetrical syndactyly hands seen with Apert Syndrome:
Type I: Spade – can see a thumb and 4th web space with syndactaly
Type II: Spoon or Mitten – can see a separate thumb or an individual nail for the thumb, all four digits are in a group.
Type III: Hoof or Rosebud: no thumb is visualized on inspection. Thumb is fused along with all 4 digits. It is often difficult for the X-Ray to reveal the findings due to bone overlaps. No separate thumb or nail is observed.
Treatment of the Apert hand is complex and often numerous procedures are required. Surgeries include: opening of the 1st web space, separation of fingers with inter-digital webspace releases, realignment of the thumb, and correction of clinodactyly. Surgical options to improve hand function are more successful for type I and less effective for type II. Each case is evaluated individually and decisions are made for each patient due to the complexity of this syndrome.