Expert Reviewed By: Dr. Brandon Colby MD
Macular corneal dystrophy type II is a rare genetic eye disorder that affects the cornea, the clear outer layer of the eye. It is characterized by progressive clouding of the cornea, leading to vision impairment and eventual blindness. Understanding the underlying genetic causes and utilizing genetic testing can help in diagnosing and managing this rare condition. This article aims to provide a comprehensive overview of macular corneal dystrophy type II, its diagnosis, and the role of genetic testing in its management.
Understanding Macular Corneal Dystrophy Type II
Macular corneal dystrophy type II is caused by mutations in the CHST6 gene, which is responsible for the production of an enzyme called corneal N-acetylglucosamine-6-sulfotransferase. This enzyme plays a crucial role in the synthesis of a molecule called keratan sulfate, which is a vital component of the cornea. The mutations in the CHST6 gene lead to the production of a defective enzyme, resulting in the accumulation of abnormal keratan sulfate in the cornea. This accumulation causes the cornea to become cloudy, leading to vision problems [1].
Diagnosing Macular Corneal Dystrophy Type II
The diagnosis of macular corneal dystrophy type II involves a thorough clinical examination and a detailed assessment of the patient's medical and family history. In some cases, a corneal biopsy may be performed to examine the corneal tissue for the presence of abnormal keratan sulfate deposits. Additionally, genetic testing can be used to confirm the diagnosis by identifying the specific mutations in the CHST6 gene [2].
Genetic Testing: Identifying the Culprit
Genetic testing involves analyzing the patient's DNA to identify the specific mutations in the CHST6 gene that cause macular corneal dystrophy type II. This can be done using various techniques, such as DNA sequencing or gene-targeted deletion/duplication analysis. Genetic testing not only helps confirm the diagnosis but also provides valuable information about the severity and prognosis of the disease, enabling better management and treatment planning [2].
Genetic Testing: A Tool for Family Planning and Prenatal Diagnosis
As macular corneal dystrophy type II is an inherited disorder, genetic testing can also be used for family planning and prenatal diagnosis. Couples with a family history of the disease can undergo genetic testing to determine their carrier status and assess the risk of passing the condition to their children. Additionally, prenatal testing can be performed during pregnancy to identify the presence of CHST6 gene mutations in the developing fetus, enabling early diagnosis and management planning [2].
Managing Macular Corneal Dystrophy Type II
There is currently no cure for macular corneal dystrophy type II, and the management of the condition primarily focuses on alleviating symptoms and preserving vision. Treatment options include the use of corrective lenses, lubricating eye drops, and, in severe cases, corneal transplantation. Penetrating keratoplasty is a surgical procedure that involves replacing the damaged cornea with healthy donor tissue. However, it is important to note that recurrence of the disease after corneal transplantation has been reported in some cases [4].
In conclusion, understanding the genetic basis of macular corneal dystrophy type II and utilizing genetic testing can significantly aid in the diagnosis and management of this rare eye disorder. Genetic testing can also be a valuable tool for family planning and prenatal diagnosis, enabling early intervention and better outcomes for affected individuals.
About The Expert Reviewer
Dr. Brandon Colby MD is a US physician specializing in the personalized prevention of disease through the use of genomic technologies. He’s an expert in genetic testing, genetic analysis, and precision medicine. Dr. Colby is also the Founder of and the author of Outsmart Your Genes.
Dr. Colby holds an MD from the Mount Sinai School of Medicine, an MBA from Stanford University’s Graduate School of Business, and a degree in Genetics with Honors from the University of Michigan. He is an Affiliate Specialist of the American College of Medical Genetics and Genomics (ACMG), an Associate of the American College of Preventive Medicine (ACPM), and a member of the National Society of Genetic Counselors (NSGC)