Agnathia: Abnormalities and Associated Factors.. The upper or lower jaw in whole or in part. Lack of development of the middle and inner ear and zygomatic arches and temporal bone, muscle and nerves

Absence of jaw Agnathia:

You've accurately described agnathia, a rare congenital condition characterized by the partial or complete absence of the jawbone(s). Here's a breakdown of your points and some additional information:

Types of Agnathia:

- Complete Agnathia:

Refers to the absence of both the upper and lower jawbones.

- Partial Agnathia:

Involves the absence of a portion of one or both jawbones. This can further be categorized based on the missing parts:

• Microgenia: Small or underdeveloped jawbone.
• Ramus Agnathia: Absence of the ramus, the vertical branch of the lower jawbone connecting to the skull.
• Condylar Agnathia: Absence of the condyle, the rounded knob at the end of the ramus that articulates with the skull.

Frequency:

• Partial agnathia is more common than complete agnathia.
• Ramus and condyle agnathia with accompanying ear malformations are the most frequently observed form of partial agnathia.

Associated Abnormalities:

• Ear abnormalities, including microtia (small ears), anotia (absent ears), and synotia (fused ears), often accompany agnathia, particularly when the ramus and condyle are affected. This is because these structures share a common embryonic origin.
• The middle and inner ear may also be underdeveloped or absent.
• The zygomatic arches (cheekbones) and temporal bone (part of the skull) may be malformed or stunted.
• Facial muscles and nerves controlling jaw movement may be missing or abnormal.

Causes:

• The exact cause of agnathia is often unknown, but it's believed to be related to abnormal development of the first pharyngeal arch during early pregnancy.
• Genetic factors, chromosome abnormalities, and certain medications or toxins during pregnancy can contribute to the risk.

Treatment:

• Reconstruction surgery using bone grafting and other techniques is often used to improve facial appearance and function.
• Supportive care, including speech therapy and feeding assistance, may be necessary depending on the severity of the condition.

Additional Information:

- Prenatal diagnosis:

Agnathia can sometimes be detected during prenatal ultrasound.

- Psychological support:

Individuals with agnathia may face social and emotional challenges due to their facial differences. Access to psychological support can be beneficial.