How is Treacher Collins syndrome diagnosed?

Diagnosis of Treacher Collins Syndrome

Treacher Collins syndrome (TCS), also known as mandibulofacial dysostosis, is a rare genetic disorder that affects the development of facial bones and tissues. It is typically diagnosed based on a combination of physical examination, medical history, and genetic testing.

Physical Examination

During a physical examination, a healthcare professional will carefully assess the individual's facial features and look for characteristic signs of Treacher Collins syndrome. These signs may include:

• Underdeveloped or absent cheekbones: The zygomatic bones, which form the cheeks, may be small or missing.


• Downward slanting eyes: The eyes may be positioned lower than normal, and the lower eyelids may be droopy.


• Small jaw and chin: The lower jaw (mandible) may be small and set back, leading to a receding chin.


• Cleft palate: A gap in the roof of the mouth may be present, which can cause feeding and speech difficulties.


• Hearing loss: Some individuals with TCS may have hearing loss due to malformation of the middle ear.

These physical features are often present at birth and can vary in severity among affected individuals. The examination may also involve assessing other body systems to identify any associated abnormalities.

Medical History

A detailed medical history is crucial in the diagnosis of Treacher Collins syndrome. The healthcare provider will ask questions about the individual's family history, including whether any close relatives have been diagnosed with TCS or have similar facial abnormalities. This information helps in understanding the inheritance pattern of the condition.

Additionally, the healthcare provider will inquire about any other symptoms or medical conditions the individual may have, as Treacher Collins syndrome can be associated with other abnormalities affecting the eyes, ears, and airway.

Genetic Testing

Genetic testing plays a vital role in confirming the diagnosis of Treacher Collins syndrome. It involves analyzing the individual's DNA to identify specific genetic mutations associated with TCS. The two main types of genetic tests used are:

1. Sequencing: This test examines the entire coding region of the TCOF1 gene, which is the most commonly affected gene in TCS. It looks for changes or mutations in the gene that can cause the syndrome.


2. Deletion/duplication analysis: This test checks for larger genetic alterations, such as deletions or duplications, within the TCOF1 gene.

Genetic testing can be performed using a blood sample or a saliva sample, depending on the laboratory's preference. The results of these tests can confirm the presence of Treacher Collins syndrome and help determine the specific genetic cause.

Additional Tests

In some cases, additional tests may be recommended to assess the extent of the condition and identify any associated complications. These tests may include:

• Hearing evaluation: A hearing test, such as an audiogram, can determine the severity and type of hearing loss, if present.


• Imaging studies: X-rays, CT scans, or MRI scans may be performed to visualize the facial bones and assess their structure and development.


• Speech evaluation: A speech-language pathologist may evaluate the individual's speech and feeding abilities to identify any difficulties caused by cleft palate or other related issues.

These additional tests help in providing a comprehensive understanding of the individual's condition and guide the management and treatment plan.

Conclusion

Treacher Collins syndrome is diagnosed through a combination of physical examination, medical history, and genetic testing. The characteristic facial features observed during the physical examination, along with the presence of other associated abnormalities, provide important clues for diagnosis. Genetic testing, particularly sequencing and deletion/duplication analysis of the TCOF1 gene, confirms the diagnosis and identifies the specific genetic cause. Additional tests, such as hearing evaluations and imaging studies, may be performed to assess the extent of the condition and associated complications. Early diagnosis is crucial in managing Treacher Collins syndrome and providing appropriate medical care and support.