JScreen now tests for the genetic condition fragile X syndrome on women as part of the Ashkenazi Jewish Panel and the Expanded Panel. Fragile X syndrome causes mental retardation and behavior problems and affects males more significantly than females.

Walker-Warburg syndrome (WWS) is an inherited condition causing a number of symptoms including muscle weakness, vision abnormalities, brain structure abnormalities, and severe mental disability. WWS causes congenital muscular dystrophy, a form of muscle weakness that is present from birth or develops shortly after birth. It causes an infant to feel floppy in all of his or her muscles, including those of the face. He or she may also exhibit involuntary muscle jerks or twitches. Eye problems associated with WWS include blindness and cataracts, among others.

Usher syndrome type 3 is an inherited disease that causes progressive hearing loss and vision impairment. The rate at which hearing and vision decline varies greatly from person to person, even among those in the same family. In some people, the hearing and/or vision loss can be profound, while in others it can be milder. People with Usher syndrome type 3 are born with normal hearing and most commonly develop hearing loss in their teenage years, requiring hearing aids by mid- to late-adulthood. By middle age, they are often completely deaf.

Usher syndrome type 1F is an inherited disease that causes profound hearing loss from birth and impairs vision beginning in adolescence. Infants with Usher syndrome type 1F are profoundly deaf in both ears at birth. This hearing loss does not typically respond to hearing aids, though it may benefit from cochlear implants. Without early interventions, the child may not develop speech abilities.

Spinal muscular atrophy (SMA) is a disease in which motor nerves in the brain and spinal cord die, impairing a person’s ability to move. These nerves control our ability to sit up, crawl, and walk. In severe cases, a person will not be able to sit up independently, and their breathing and swallowing may also be impaired. In the mildest cases, symptoms begin in adulthood and make independent movement more difficult, but still possible. Historically, five main subtypes of spinal muscular atrophy were described, but use of these subtypes is changing due to the impact of treatments on the health and lifespan of people with SMA.

Niemann-Pick disease (NPD) is a rare inherited disorder caused by changes in any of these genes: SMPD1, NPC1, or NPC2. Those affected by Niemann-Pick disease are not able to break down a substance within cells, resulting in a buildup in the liver, spleen, and brain. Niemann-Pick disease caused by the SMPD1 gene has two forms: A and B. Type A is the more severe type. Infants with type A develop symptoms such as large liver and spleen and difficulty feeding within the first few months of life. Their intellectual and motor skills will rapidly decline, and it can be fatal by age 2-3 years. Niemann-Pick type B is less severe and starts later than type A. Other symptoms may include lung infections and poor growth.

Nemaline myopathy (NEB-related) is a genetic disease that causes weakness in the muscles of the face, neck, arms, and legs. Along with a tendency toward decreased muscle tone, this weakness can delay motor functions such as walking. In some cases, it can also cause difficulty eating and breathing, notably in infancy. There are at least six different forms of nemaline myopathy, caused by mutations in several genes. Counsyl screens for a form of the disease caused by a mutation in the NEB gene. This form, most common in Ashkenazi Jews, usually causes a milder form of the disease known as “typical” or “typical congenital” nemaline myopathy.

Mucolipidosis IV is a rare inherited condition that affects the development of the nerves. In about 15% of cases, it also causes existing nerves to degenerate. Most infants with the condition are unable to sit up, crawl, or control their hand motions. They also chew and swallow very slowly, because the muscles of their mouth and face move slowly or not at all.

Maple syrup urine disease (MSUD) type 1B is an inherited metabolic disorder named for the characteristic maple syrup smell of the affected person’s urine. If carefully treated with a low-protein diet, people with MSUD can live fairly normal lives.MSUD is caused by the lack of an enzyme needed to break down three amino acids: leucine, isoleucine, and valine, which are collectively known as the branched-chain amino acids. These amino acids are found in all foods containing protein.

Lipoamide dehydrogenase deficiency (E3) is a rare inherited disease that causes metabolic abnormalities, neurological damage, poor muscle tone, developmental delay, and movement problems. In some people, it is fatal in childhood. Infants with E3 often appear normal until the age of 8 weeks to 6 months when they develop severe lactic acidosis, a buildup of lactic acid in the body that causes vomiting, abdominal pain, and rapid breathing. If untreated, it can be fatal.

Joubert syndrome 2 (JBTS2) is a disease that causes abnormalities in the brain structure leading to developmental delay, the inability to coordinate muscle movement, involuntary eye movements, and difficulty moving the eyes from side to side. Individuals may also have intellectual disability. At birth, children with JBTS2 have poor muscle tone. Their eyes rapidly move involuntarily and may rotate inward.

Glycogen storage disease (GSD) type Ia, sometimes called von Gierke’s disease, is an inherited disease that interferes with the way the body turns food into energy. Due to a missing or impaired enzyme, the body is unable to maintain normal blood sugar levels between meals, leading to low blood sugar (hypoglycemia). As a result, both children and adults with GSD type Ia will be chronically hungry, tired, and irritable unless they eat regularly—typically every 1 to 3 hours during the day and every 3 to 4 hours at night. If their blood sugar reaches a critically low level, some may experience seizures.

Gaucher disease is a genetic disorder caused by changes in the GBA gene that affect the body’s ability to break down a substance found in cell membranes. This substance accumulates in the liver, spleen, and bone marrow, leading to a wide range of symptoms. There are multiple types of Gaucher disease described below. Treatments can help with many of the symptoms. Type 1 Gaucher disease is the most common form, with a range of symptoms that can onsetfrom childhood to late adulthood.

Fanconi anemia type C is an inherited disorder in which the body cannot properly produce a protein that protects DNA from damage. This defective protein results in an impaired ability of bone marrow to produce all types of blood cells. Without a sufficient number of red blood cells, the body does not receive enough oxygen, which can lead to abnormal bones and organs as well as developmental delay. A shortage of white blood cells makes the body more susceptible to infection and cancer. A reduction in blood platelets make it difficult for the blood to clot when an injury arises.

Familial dysautonomia is an inherited condition that causes nerve cells to deteriorate. It affects the autonomic nervous system, which controls involuntary actions such as breathing, tear production, blood pressure, and body temperature. It also affects the sensory nervous system, which controls senses such as the abilities to perceive taste, pressure, pain, and temperature. Early symptoms in infants include feeding problems, poor growth, lack of tears, poor muscle tone, frequent lung infections, and marked fluctuations in body temperature. Until about age 6, children with the condition may also hold their breath for long periods of time, which may cause fainting or make their lips or skin appear blue. They may learn to walk and talk later than average.

Canavan disease is an inherited disorder that destroys the myelin sheath, the white matter that insulates nerve cells in the brain. It causes overall muscle weakness and developmental delay leading to severe mental disability. Symptoms usually begin at 3 to 5 months of age with poor muscle tone (hypotonia), which causes problems turning over, controlling head movements, and sitting up. The infant’s head also becomes rapidly larger.

Bloom syndrome, also known as Bloom’s syndrome, is an inherited condition most easily noticed by the person’s extremely small stature. People with Bloom syndrome have chromosomes which often break and re-arrange. This instability results in high rates of cancer early in life. Some people with the disease develop cancerous tumors before the age of 10, but more commonly cancer appears beginning in the late teens or early to mid-20s.

ABCC8-related hyperinsulinism, also called congenital hyperinsulinism, is an inherited condition in which the pancreas releases inappropriately large quantities of the hormone insulin, leading to low blood sugar (hypoglycemia). When blood sugar drops to dangerously low levels, seizures and permanent brain damage may occur. If untreated, the condition could ultimately be fatal.ABCC8 refers to the name of the gene that causes this disease. Other genes have been identified which also cause hyperinsulinism.