Unlocking the Secrets of Familial Atypical Mycobacteriosis: Genetic Testing and Beyond

Familial Atypical Mycobacteriosis, Autosomal Recessive

Expert Reviewed By: Dr. Brandon Colby MD

Familial Atypical Mycobacteriosis, Autosomal Recessive (FAM-AR) is a rare genetic disorder that affects the immune system, making it difficult for affected individuals to fight off certain types of infections. This article aims to provide an understanding of FAM-AR, the methods of diagnosing it, and the role of genetic testing in managing the disease.

Understanding Familial Atypical Mycobacteriosis

FAM-AR is a type of primary immunodeficiency disease, which means that it is present from birth and results from genetic mutations. In the case of FAM-AR, the mutations occur in both copies of a gene responsible for producing a protein called interferon-gamma receptor 1 (IFNGR1). This protein plays a crucial role in the immune system's ability to recognize and fight off infections caused by atypical mycobacteria.

Atypical mycobacteria are a group of bacteria that are related to the bacteria that cause tuberculosis and leprosy. They are commonly found in the environment, such as in soil and water, and can cause a variety of infections in humans. In individuals with FAM-AR, their immune system is unable to effectively combat these infections, leading to recurrent and severe cases of atypical mycobacterial disease.

Diagnosing Familial Atypical Mycobacteriosis

Diagnosing FAM-AR can be challenging, as the symptoms of the disease can vary widely and may resemble other conditions. Some common signs of FAM-AR include:

Recurrent and severe infections caused by atypical mycobacteria, often affecting the skin, bones, and lymph nodes
Failure to thrive or poor growth in children
Anemia or other blood abnormalities
Enlarged liver or spleen

To diagnose FAM-AR, doctors will typically take a detailed medical history, perform a physical examination, and order various tests, including blood tests and imaging studies. However, the definitive diagnosis of FAM-AR relies on genetic testing.

The Role of Genetic Testing in Familial Atypical Mycobacteriosis

Confirming the Diagnosis

Genetic testing is essential for confirming a diagnosis of FAM-AR. By analyzing DNA samples, usually obtained from blood, genetic testing can identify the specific mutations in the IFNGR1 gene that are responsible for the disease. This information is crucial for establishing an accurate diagnosis and guiding the appropriate treatment and management strategies for affected individuals.

Carrier Testing

As FAM-AR is an autosomal recessive disorder, it means that both parents must carry a mutated copy of the IFNGR1 gene for a child to be affected. Genetic testing can be used to identify carriers of the mutated gene, who may be at risk of having a child with FAM-AR. This information can be valuable for couples who are planning to have children, particularly if there is a family history of the disease.

Prenatal and Preimplantation Genetic Testing

For couples who are known carriers of the mutated IFNGR1 gene, prenatal genetic testing can be performed during pregnancy to determine if the fetus is affected by FAM-AR. This testing typically involves procedures such as chorionic villus sampling (CVS) or amniocentesis, which allow for the collection of fetal cells for DNA analysis.

Alternatively, preimplantation genetic testing (PGT) can be performed as part of in vitro fertilization (IVF) procedures. This involves testing embryos for the presence of the mutated IFNGR1 gene before they are implanted in the uterus. PGT can help couples reduce the risk of having a child affected by FAM-AR.

Conclusion

Familial Atypical Mycobacteriosis, Autosomal Recessive, is a rare genetic disorder that poses significant challenges for affected individuals and their families. Genetic testing plays a crucial role in diagnosing the condition, identifying carriers, and guiding reproductive decisions for couples at risk of having a child with FAM-AR. By understanding the disease and utilizing the available genetic testing options, families can make informed decisions and work with healthcare providers to manage and treat FAM-AR effectively.

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)