Otopalatodigital syndrome type 1
Otopalatodigital syndrome type 1 is a rare genetic disorder primarily characterized by skeletal abnormalities, hearing loss, and distinct facial features.
Overview
This condition is part of a group known as otopalatodigital spectrum disorders. It is generally the mildest form, involving malformations of the tiny bones in the ears, palate development issues, and skeletal abnormalities in the digits.
Symptoms
- Facial Features: Wide-set and downward-slanting eyes, prominent brow ridges, and a broad, flat nose.
- Skeletal Abnormalities: Blunt, square-shaped (spatulate) fingertips, shortened thumbs and big toes, unusually long second toes, and a wide gap between the first and second toes (sandal gap).
- Other Features: Hearing loss, potential opening in the roof of the mouth (cleft palate), hypodontia (fewer teeth than normal), mild bowing of limbs, and limited joint range of motion.
Causes
The syndrome is caused by "gain-of-function" mutations in the FLNA gene. This gene produces the protein filamin A, which helps build the cytoskeleton—the network of filaments that gives cells structure and allows them to move. These mutations increase the protein's ability to bind to actin, which is believed to impair the stability of the cytoskeleton and disrupt skeletal development.
Inheritance
This condition is inherited in an X-linked pattern. Because males have only one X chromosome, a single mutation is sufficient to cause the condition. Females have two X chromosomes; one altered copy may lead to milder features or no symptoms at all. Fathers cannot pass X-linked traits to their sons.
