Fechtner syndrome is a rare, inherited disorder affecting several body systems. It belongs to a group of conditions known as MYH9-related disorders, identified by a combination of health issues including blood platelet irregularities, hearing impairment, and kidney problems. These characteristics present together as a result of a single underlying genetic anomaly. The condition’s features can vary in severity among individuals, but the pattern of affected systems remains consistent.
The Genetic Basis
The cause of Fechtner syndrome is a mutation in the MYH9 gene, which provides instructions for making a protein called non-muscle myosin heavy chain IIA (NMMHC-IIA). This protein is active in many cell types, playing a part in processes like cell division, movement, and maintaining cell shape.
When a mutation occurs in the MYH9 gene, the NMMHC-IIA protein becomes defective and cannot function correctly. This disrupts the normal activities of certain cells, particularly platelets, as well as specific cells in the inner ear and kidneys. The malfunctioning protein can form clumps, known as inclusion bodies, within some blood cells.
Fechtner syndrome is inherited in an autosomal dominant pattern, meaning one copy of the mutated gene from a parent is sufficient to cause the disorder. An individual with the syndrome has a 50% chance of passing the mutated gene to each of their children. The condition does not skip generations and affects males and females equally.
Symptoms and Associated Conditions
One effect of Fechtner syndrome is on the blood. Individuals have thrombocytopenia (a low platelet count), and their existing platelets are unusually large, a condition called macrothrombocytopenia. This combination impairs blood clotting, leading to easy bruising, frequent nosebleeds, or prolonged bleeding after injury or surgery.
Progressive hearing loss is another aspect of the syndrome. The hearing impairment is sensorineural, meaning it originates from a problem within the inner ear or the nerve pathways to the brain. The hearing loss begins in adolescence or early adulthood and worsens over time, with severity ranging from mild to profound.
Kidney function is also frequently compromised. The condition can cause nephritis (kidney inflammation), which damages the glomeruli, the kidneys’ filtering units. Over years, this damage can lead to a gradual decline in kidney function, proteinuria (excess protein in the urine), and high blood pressure. In some cases, this can lead to kidney failure.
Ocular abnormalities, specifically the development of cataracts, are also associated with the disorder. Cataracts involve the clouding of the eye’s lens, which can blur vision. In Fechtner syndrome, these cataracts often appear at a younger age than in the general population.
Diagnostic Process
Diagnosis begins with a clinical evaluation of the patient’s symptoms and family medical history, focusing on the combination of bleeding tendencies, hearing difficulties, and kidney disease.
Laboratory tests provide further evidence. A complete blood count (CBC) confirms thrombocytopenia, and a peripheral blood smear is used to identify abnormally large platelets. The smear may also reveal the presence of Döhle-like bodies, which are the protein inclusion bodies within certain white blood cells.
To confirm the diagnosis, molecular genetic testing is required to analyze the individual’s DNA for a mutation in the MYH9 gene. Finding a pathogenic variant in this gene confirms the patient’s symptoms are part of the MYH9-related disorders spectrum. Functional tests are also used to assess symptom severity, including audiometry for hearing loss, urinalysis for kidney function, and an eye exam to detect cataracts.
Management and Treatment Approaches
There is no cure for Fechtner syndrome, so medical care focuses on managing symptoms and preventing complications. This approach involves regular monitoring by a team of specialists, including a hematologist for blood issues, a nephrologist for kidney care, and an audiologist for hearing.
To address the bleeding risk from thrombocytopenia, most individuals only require monitoring. Platelet transfusions are reserved for severe bleeding or as a preventive measure before major surgery. Medications that interfere with platelet function, such as aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs), should be avoided.
Managing progressive hearing loss involves the use of hearing aids. As the impairment advances, cochlear implants may be considered. A cochlear implant is a surgically implanted device that bypasses damaged parts of the inner ear to directly stimulate the auditory nerve, providing a sense of sound to a person who is profoundly deaf or severely hard-of-hearing.
For kidney complications, the goal is to slow disease progression through regular monitoring of blood pressure and urine protein levels. Medications like ACE inhibitors or ARBs are often prescribed to lower blood pressure and reduce protein leakage from the kidneys. If the condition advances to end-stage renal disease, options include dialysis or a kidney transplant. Cataracts are treated with surgery to replace the clouded lens with an artificial one.