Question: When and how do you know when you have congenital night blindness?

Reference:
 X-linked congenital stationary night blindness X-linked CSNB Congenital stationary night blindness with myopia Hemeralopia-myopia X-linked CSNB Congenital stationary night blindness with myopia Hemeralopia-myopia Myopia-night blindness See More Summary X-linked congenital stationary night blindness (XLCSNB) is a disorder of the retina. People with this condition typically experience night blindness and other vision problems, including loss of sharpness ( reduced visual acuity), severe nearsightedness (myopia), nystagmus , and strabismus . Color vision is typically not affected. These vision problems are usually evident at birth, but tend to be stable (stationary) over time. There are two major types of XLCSNB: the complete form and the incomplete form. Both types have very similar signs and symptoms. However, everyone with the complete form has night blindness, while not all people with the incomplete form have night blindness. The types are distinguished by their genetic cause. [1] Symptoms This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom. Showing of Medical Terms Other Names Learn More: HPO ID 30%-79% of people have these symptoms Abnormality of macular pigmentation 0008002 High myopia Severe near sightedness Severely close sighted Severely near sighted 0011003 Nyctalopia Night blindness Night-blindness Poor night vision 0000662 Optic disc hypoplasia 0007766 Reduced visual acuity Decreased clarity of vision 0007663 5%-29% of people have these symptoms Nystagmus Involuntary, rapid, rhythmic eye movements 0000639 Strabismus Cross-eyed Squint Squint eyes 0000486 Percent of people who have these symptoms is not available through HPO Congenital stationary night blindness Night blindness since birth 0007642 Hemeralopia Day blindness 0012047 Myopia Close sighted Near sighted Near sightedness Nearsightedness 0000545 X-linked inheritance 0001417 X-linked recessive inheritance 0001419 Showing of Diagnosis Yes. About 45% of individuals with XLCSNB have the complete form, which is caused by mutations in the NYX gene . The other 55% have the incomplete form, which is caused by mutations in the CACNA1F gene. [2] The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional. Find a Specialist If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments. If you can't find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care. You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists. Healthcare Resources To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by the American College of Medical Genetics and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from Genetics Home Reference. 

Answer: X-linked congenital stationary night blindness (XLCSNB) is a disorder of the retina. People with this condition typically experience night blindness and other vision problems, including loss of sharpness ( reduced visual acuity), severe nearsightedness (myopia), nystagmus , and strabismus . Color vision is typically not affected. These vision problems are usually evident at birth, but tend to be stable (stationary) over time.