Health and Fitness

 Leber Hereditary Optic Neuropathy (LHON) Overview Leber hereditary optic neuropathy (LHON) is a genetically inherited disease that causes vision loss. Most people who inherit the condition develop blurred vision that gets progressively worse over a course of about six months. Vision loss may start in one eye and then progress to both eyes several months later. It usually starts in late childhood to early adulthood. Most people with LHON will become legally blind. Leber hereditary optic neuropathy is also called Leber’s disease. It’s named for Dr. Theodore Leber, who studied the disease. “Hereditary” means that you inherit it, and “optic neuropathy” means it’s a disease that affects your optic nerve. Your optic nerve is what carries visual signals from your eye to your brain so that your brain can “see.” Damage to your optic nerve is one way that you can lose your vision. The standard version of Leber hereditary optic neuropathy (LHON) only affects your optic nerves, and vision los...

 Leber congenital amaurosis Overview Leber’s congenital amaurosis (LCA) is a rare condition that affects the retinas in babies’ eyes. Babies born with LCA have low vision — they often lose some or all of their sight. Many babies who have LCA are born blind. LCA is a congenital condition, which means your baby is born with it. It’s caused by genetic mutations that affect how your child’s retinas develop. The retina is the layer at the very back of your eyeball. Photoreceptors in your retinas process light into an electrical signal that your brain can understand as images you see. Rods are photoreceptors that help you see at night and in dim light. Cones process color and make up most of your usual vision. Leber’s congenital amaurosis makes the rods and cones in your baby’s retinas malfunction. It changes how much electrical energy your child’s retinas can use and process. The less electrical activity there is, the less sight your child will have. If there’s no electrical activity in...

 Laurence-Moon Syndrome Overview Laurence-Moon syndrome (LNMS) is a genetic condition that results in a complex association of problems that affect several different body parts. People with LNMS may have difficulties with functions of the brain, eyes, ears, stomach, kidneys, hands and feet. They often also demonstrate a tendency to short stature and obesity. Because of the many complications seen in this condition, it is important that the patient has a strong, comprehensive health care team. LNMS was later termed Laurence-Moon-Bardet-Biedl syndrome because of similarities with Bardet-Biedl syndrome (BBS). It is often considered, but still debated, whether BBS is a distinct condition. Arguments are based on differences in the underlying genetic causes of these the disorders (see Related Disorders). These two disorders also share similarity to Oliver-McFarlane syndrome (OMS). All three conditions are characterized by progressive blindness, obesity, and learning disabilities. Differe...

Laryngotracheoesophageal Cleft Overview A Laryngotracheoesophageal cleft (LTEC), commonly referred to as a laryngeal cleft, is an abnormal connection between the airway/windpipe (larynx and trachea) and the esophagus. A LTEC is a congenital disorder, meaning it is present at the time of birth. Children are usually diagnosed in the first two years of life. Symptoms typically appear within the first few months of life and are primarily related to difficulty eating and breathing. Symptoms may vary depending on the severity of the cleft. Children may have problems feeding and swallowing, difficulty gaining weight appropriately, coughing, hoarseness, acid reflux, noisy breathing, lung infections or trouble getting enough oxygen (respiratory distress). Treatment generally consists of surgery to repair and close the connection between the airway and esophagus. Children with milder forms of LTEC may not require surgery. In the neck, there are two main passageways—the airway in front which allo...

Laryngeal Dystonia Overview Laryngeal dystonia (LD) is a chronic voice disorder characterized by spasms of the muscles of the voice box (larynx). These muscles control the voice. The spasms can result in tightness in the throat, recurrent hoarseness, and changes in voice quality and/or difficulty speaking. The most frequent sign of this disorder is a sudden, momentary lapse or interruption of the voice. When affected individuals speak, their voice may sound strained, forced, strangled, breathy, or whispery. Speaking becomes less natural, and often requires great effort. In severe cases, an affected individual may be barely able to speak. LD can potentially cause significant quality of life issues for affected individuals impacting both work and social situations. There is no cure for LD, but the disorder can be treated. In most cases, the cause of LD is not known. LD is a form of dystonia, a group of movement disorders that vary in their symptoms, causes, progression, and treatments. T...

 Larsen Syndrome Overview Larsen syndrome is a rare genetic disorder that has been associated with a wide variety of different symptoms. Characteristic findings of the disorder include dislocations of the large joints, skeletal malformations, and distinctive facial and limb features. Additional findings may include abnormal curvature of the spine, clubfoot, short stature, and breathing (respiratory) difficulties. The classic form of Larsen syndrome is caused by mutations of the FLNB gene with a frequency of 1 in 100,000. The mutation may occur spontaneously or be inherited as an autosomal dominant trait. Introduction FLNB-related disorders are a group of disorders (including autosomal dominant Larsen syndrome) that occur due to mutations of the Filamin B gene (FLNB) gene. This group includes atelosteogenesis types I and III, boomerang dysplasia and spondylocarpotarsal syndrome. These disorders are characterized by skeletal abnormalities affecting the bones of the hands and feet, th...

  Large Granular Lymphocytic Leukemia Overview Large granular lymphocytic leukemia (LGL) is a rare type of chronic leukemia that affects specific white blood cells known as lymphocytes. Lymphocytes fight viruses and make antibodies that help fight infection. There are two types of large granular lymphocytic leukemia: T-cell large granular lymphocytic leukemia (T-LGL) and chronic lymphoproliferative disorder of NK cells (CLPD-NK). These conditions start in white blood cells called cytotoxic T cells or natural killer cells. Both types of large granular lymphocytic leukemia grow slowly. They typically affect people age 60 and older. Healthcare providers can treat LGL, but the condition sometimes comes back and can become a chronic health issue. LGL is a type of chronic lymphocytic leukemia that occurs when certain T cells and natural killer cells mutate, becoming abnormal cells that keep your bone marrow from producing normal blood cells. People with LGL often develop neutropenia, mea...