Johanson-Blizzard syndrome (JBS), named for two of the first scientists to study it, is a type of ectodermal dysplasia, a group of diseases that affect the outer layer of a developing embryo. This layer, called the embryonic ectoderm, develops into the hair, skin, nails, and teeth. Symptoms of JBS affect the teeth, hair, face, brain, thyroid gland, and ears.
JBS is caused by a mutation, or defect, in the ubiquitin protein ligase (UBR1) gene. This gene seems to have a role in the normal functioning of the pancreas. People with JBS usually have decreased functioning of the pancreas, which often causes short stature and poor nutrient absorption, and is generally the cause of death in these individuals.
JBS is extremely rare, with about only 30 known cases worldwide. More cases have been reported in females than in males, but females tend to have milder symptoms. Incidence is higher among children of parents who are consanguineous, meaning they are related and share a blood line.
There is no cure for JBS. Treatment aims to reduce symptoms and prevent complications. Even when treated aggressively, people with JBS often die in infancy or early childhood. This is largely because of problems associated with malnutrition.
Because Johanson-Blizzard syndrome (JBS) is a genetic disorder, the only known risk factor is a family history of the condition. Incidence of JBS is higher among children of consanguineous parents, meaning they are related and share a blood line.
Inheritance: Johanson-Blizzard syndrome (JBS) is associated with mutations on the UBR1 gene. This gene seems to have a role in the normal functioning of the pancreas. People with JBS usually have decreased functioning of the pancreas, which often causes poor nutrient absorption, short stature, and often, death.
Autosomal recessive inheritance: The mutated UBR1 gene that causes JBS appears to be inherited, or passed down in families as an autosomal recessive trait. An individual must inherit two copies of the defective gene, one copy from each parent, for the disease to appear. People who inherit a mutation from only one parent generally have mild or no symptoms and are called "carriers" of the condition because they can pass the mutation to their children.
If one parent is a carrier, or has only one copy of the defective gene, then each child will have a 50% chance of inheriting one defective gene and also being a carrier. If both parents are carriers, each child has a 25% chance of inheriting two defective genes, a 50% chance of inheriting only one defective gene, and a 25% chance of not inheriting either defective gene. Therefore, if both parents are carriers, about one out of four children will have JBS.
X-linked dominant inheritance: Because JBS occurs predominantly in females, some researchers have suggested that the condition may be caused by an X-linked genetic mutation. Females have two copies of the X chromosome, but males have one X chromosome and one Y chromosome. Males inherit an X chromosome from their mother and a Y chromosome from their father, so a male can only inherit an X-linked gene from his mother.
Random occurrence: It is unknown whether JBS can occur as the result of a spontaneous genetic mutation with no family history of the disease.
SIGNS AND SYMPTOMS
Brain abnormalities: The brains of people with Johanson-Blizzard syndrome (JBS) tend to be smaller than normal.
Dental problems: People with JBS are likely to have dental problems. Baby teeth tend to be small and malformed, while permanent teeth may be absent or badly shaped. In some cases, the permanent teeth fail to come in.
Developmental problems: Fetuses with JBS may not grow properly in the womb, a condition called intrauterine growth retardation. Infants may have low birth weight, failure to thrive, poor muscle tone, and feeding difficulties. These symptoms, combined with malnutrition, generally lead to the short stature and psychomotor development problems seen in JBS.
Digestive disorders: People with JBS often have trouble absorbing nutrients and fat in the digestive tract because of abnormal functioning of the pancreas. In particular, the enzymes essential to nutrient absorption are absent or deficient in JBS. This may lead to chronic diarrhea and poor nutritional status, including malnutrition and vitamin and mineral deficiencies. This is often the cause of death in individuals with JBS.
Facial symptoms: Facial signs and symptoms of JBS include a small, short, beak-like nose and absent or underdeveloped nostrils.
Hearing problems: Many people with JBS are born with either impaired hearing or profound deafness. This generally leads to speech problems.
Intellectual disabilities: The intellectual ability of people with JBS varies widely. About 60% of patients with JBS have moderate intellectual disability, while others have minor intellectual disabilities or normal intelligence. Intellectual disability among patients with JBS often shows itself in behavioral problems, which may compromise medical care and decrease the patient's quality of life.
Intellectual disabilities typically range from mild to profound. Researchers usually use intelligence quotient (IQ) tests to measure the severity of a person's intellectual disabilities. Individuals who have IQs of 85-115 are considered to have average intelligence.
Patients with mild intellectual disabilities have IQs of 52-69. From birth to age six, patients are able to develop normal social and communication skills, but motor coordination is slightly impaired. By late adolescence, patients are able to learn up to about a sixth-grade level. They are generally able to learn appropriate social skills. Adults with mild intellectual disabilities are usually able to work and support themselves, although some patients may need help during times of social or financial stress.
Patients with moderate intellectual disabilities have IQs of 36-51. Children younger than six years of age are able to talk or communicate with others, but social awareness is generally poor. Motor coordination is typically fair. Adolescents are able to learn some occupational and social skills. For instance, they may be able to learn how to travel alone in familiar places. Adults may be able to support themselves with a job. They usually require guidance and assistance during mild social or financial stress.
Patients with severe intellectual disabilities have IQs of 20-35. Young children can say a few words, but their speech is limited. Motor coordination is generally poor. Adolescents can usually talk or communicate with others. They are able to learn simple tasks. Adults typically require lifelong assistance and guidance with daily activities.
Patients with profound intellectual disabilities have IQs of 19 or lower. Children younger than six years old have very little motor coordination and may require nursing care. Adolescents typically have limited motor and communication skills. Adults usually require lifelong nursing care.
Skin problems: Skin problems in people with JBS include poor skin quality and skin breakdown. In addition, the hair on the scalp tends to be sparse, dry, and coarse with patches of baldness. There is a distinctive "upsweep" of the hair at the forehead that is characteristic of JBS.
Thyroid problems: About one-third of patients with JBS have an underactive thyroid gland, which leads to fatigue and may contribute to problems with growth and psychomotor development. The exact cause of thyroid problems seen in JBS is not known.
Other: Less frequent symptoms include abnormal skull development, delayed bone age, uterine and vaginal problems, anal deformities, anemia, small eyes, droopy eyelids, problems with the tear ducts, problems with the roof of the mouth, underdeveloped or absent nipples, swelling, abnormal cry, heart problems, and stillbirth or neonatal death. Recently, a skin symptom called caf©-au-lait spots was described in a patient with JBS, although this is not a common sign. There has been one report of a patient with JBS and diabetes mellitus.
General: Johanson-Blizzard syndrome (JBS) can usually be diagnosed at birth. Diagnosis should begin with a detailed family history and complete physical exam. A clinician will look for the facial, skin, and mouth abnormalities that are distinctive of JBS.
Blood tests: Blood tests can screen for thyroid problems and check for levels of vitamins and minerals.
Hearing test: A clinician may refer parents of a child with JBS to an audiologist for a hearing test. A hearing test can assess the degree and type of the hearing loss. The audiologist can also assess the configuration of hearing loss, such as whether it is in one or both ears, high-frequency versus low-frequency, or stable versus fluctuating.
Imaging: Imaging, such as magnetic resonance imaging (MRI), can be used to assess the health status of the pancreas and brain.
Genetic (DNA) testing: DNA tests are performed to confirm the presence of the genetic mutations that cause disease and may confirm the results from other test methods. Because JBS is so rare, it is not clear if DNA testing is feasible.
Amniotic fluid (prenatal) genetic testing: Genetic tests may also be performed on blood from a developing fetus or from amniotic fluid, which is the fluid contained in the sac that surrounds and cushions the fetus. Because taking a blood sample may cause harm to a fetus, taking samples of amniotic fluid is generally preferred. It is important to note that any prenatal test carries a risk of miscarriage. Because JBS is so rare, it is not clear if prenatal genetic testing is feasible.
Chorionic villus sampling (CVS): Chorionic villus sampling (CVS) is another type of prenatal diagnosis that can detect genetic problems in a fetus. Samples are taken from the chorionic villus, or placental tissue. As with any prenatal test, this procedure carries a risk of miscarriage. Because JBS is so rare, it is not clear if CVS is feasible.
Pre-implantation genetic diagnosis (PGD): A new procedure called pre-implantation genetic diagnosis (PGD) may be performed on embryos produced by in vitro (artificial) fertilization. This test may allow parents to implant and bring to term only the embryos that do not carry the genetic mutations that cause disease. Because JBS is so rare, it is not clear if PGD is feasible.
Diabetes: According to limited information, one person with Johanson-Blizzard syndrome (JBS) has been reported to have diabetes. As children with JBS live longer, they may develop pancreatic endocrine insufficiency, which may lead to the development of diabetes.
Infection: Because of poor nutritional status, people with JBS are susceptible to infections.
Pancreatic insufficiency: Most patients with JBS have abnormal pancreatic function. This is believed to be related to the genetic mutation in the UBR1 gene, which is involved in normal pancreatic function. Poor functioning of the pancreas contributes to malabsorption of fats, vitamins, and minerals.
General: There is currently no known cure for Johanson-Blizzard syndrome (JBS), but many treatments and therapies may help patients cope with the disorder. Treatments listed below may or may not be implemented depending on the age and general health status of the individual.
Education: Patients with JBS must have access to education tailored to their specific strengths and weaknesses. According to the Individuals with Disabilities Education Act, all children with disabilities must receive free and appropriate education. According to the law, staff at the patient's school should consult with the patient's parents or caregivers to design and write an individualized education plan. The school faculty should document the child's progress in order to ensure that the child's needs are being met.
Educational programs vary among patients. In general, most experts believe that children with disabilities should be educated alongside their nondisabled peers. The idea is that nondisabled students help the patient learn appropriate behavioral, social, and language skills. For this reason, some patients with intellectual disabilities are educated in mainstream classrooms. Others attend public schools but take special education classes or attend specialized schools that are designed to teach children with disabilities.
Behavioral therapy: Behavioral therapy may be beneficial for people with JBS. Several different types of behavioral therapy are available to help patients improve their communication and social skills, and their learning abilities and adaptive behaviors. Evidence suggests that behavioral therapy is most effective if it is started early in life.
Hearing aids: People with JBS who experience hearing loss may benefit from hearing aids. These battery-operated devices are available in three basic styles: behind-the-ear, in-the-ear, and canal. Patients should talk to their healthcare providers to determine the type of hearing aid best for them. A behind-the-ear device is used for mild to profound hearing loss. The device is worn behind the ear and is attached to a plastic ear mold inside the outer ear. In-the-ear hearing aids are worn inside the outer ear, and are used for mild to severe hearing loss. Canal hearing aids are smaller hearing aids that fit inside the patient's hearing canal. They are used for mild to moderately severe hearing loss. If hearing loss is severe, patients may benefit from cochlear implants. These electronic devices are surgically implanted inside of the ear. Unlike a hearing aid, which amplifies sound, a cochlear implant compensates for damaged parts of the inner ear.
Occupational therapy: JBS patients may benefit from occupational therapy. During these sessions, a therapist helps the child learn the skills needed to perform basic daily tasks, such as feeding, dressing, and communicating with others. Parents and caregivers can ask their children's pediatricians to recommend a therapist.
Speech-language therapy: Some patients with JBS may benefit from speech-language therapy because these individuals often develop communication skills later than normal. During speech-language therapy, a qualified speech-language professional (SLP) works with the patient on a one-to-one basis, in a small group, or in a classroom, to help the patient improve speech, language, and communication skills. Programs are tailored to the patient's individual needs.
Speech pathologists use a variety of exercises to improve the patient's communication skills. Exercises typically start simple and become more complex as therapy continues. For instance, the therapist may ask the patient to name objects, tell stories, or explain the purpose of an object.
On average, patients receive five or more hours of therapy per week for three months to several years. Doctors typically recommend that treatment is started early to ensure the best possible results for the child.
Drug therapy: Patients with severe behavioral problems, as sometimes seen in JBS, may benefit from the use of prescription psychotropic drugs. The use of drugs for behavior modification in JBS should be thoroughly discussed with a psychiatrist.
Pancreatic enzyme replacement: Pancrelipase is a medication available as a powder for infants, and as a tablet or capsule. It is used to replace the pancreatic enzymes deficient in patients with JBS and is taken with meals, including snacks, to aid in digestion. Pancrelipase can thus relieve symptoms, including malabsorption of vitamins. Dosing depends on the extent of symptoms (such as steatorrhea or fat in the stool) and the tolerance of side effects. The main side effects include nausea, abdominal pain, constipation, and diarrhea. Also seen are allergic reactions, irritation of the mouth and anus, and high levels of uric acid, which usually occurs only at high doses. The high uric acid levels will cause a gout attack only in those patients who are predisposed. A fat-soluble vitamin supplement (ADEKs©) may be given to increase these necessary nutrients along with the pancreatic enzymes.
Surgery: To correct the genital or anal abnormalities sometimes observed in JBS, surgery may be needed.
Note: Currently, there is a lack of scientific data on the use of integrative therapies for the treatment or prevention of Johanson-Blizzard syndrome (JBS). The therapies listed below have been studied for related conditions, should be used only under the supervision of a qualified healthcare provider, and should not be used in replacement of other proven therapies.
Unclear or conflicting scientific evidence:
ADEKs©: ADEKs© is a multivitamin with minerals, mainly consisting of vitamins A, D, E, and K. Vitamin C, B-complex vitamins, folic acid, and zinc, are also contained in this supplement. ADEKs© may be given to increase these necessary nutrients along with the pancreatic enzymes. This preparation uses high doses of fat-soluble vitamins (A, D, E, and K) in a water-soluble form. It is available as a tablet, liquid, drops, and chewable tablet that must be chewed or crushed before swallowing. Patients should speak with their doctor before taking any supplementation, especially before taking ADEKs©. Recommended doses should not be exceeded because of the risk of toxicity. Pregnant women and patients taking anticoagulant therapy should use ADEKs© with caution.
Bromelain: Bromelain is a digestive enzyme that comes from the stem and the fruit of the pineapple plant. There is not enough information to recommend the use of bromelain in the treatment of steatorrhea, or fat in the stool from pancreatic problems. Avoid if allergic to bromelain, pineapple, honeybee, venom, latex, birch pollen, carrots, celery, fennel, cypress pollen, grass pollen, papain, rye flour, wheat flour, or members of the Bromeliaceae
family. Use cautiously with a history of a bleeding disorder, stomach ulcers, heart disease, or liver or kidney disease. Use caution before dental or surgical procedures with a bleeding risk or while driving or operating machinery. Avoid if pregnant or breastfeeding.
General: Because Johanson-Blizzard syndrome (JBS) is an inherited condition, there is currently no known way to prevent the disease. However, a number of options are available for parents with family histories of JBS.
Genetic testing and counseling: Individuals who have JBS may meet with a genetic counselor to discuss the risks of having children with the disease. Individuals from high-risk populations, or those with family histories of JBS, may meet with a genetic counselor to determine whether they carry the gene for JBS. Carriers can be determined through detailed family histories or genetic testing.
Known carriers of JBS may undergo genetic counseling before they conceive a child. A genetic counselor can explain the options and associated risks of various tests, including pre-implantation genetic diagnosis (PGD), amniocentesis, and chorionic villus sampling (CVS).
Pre-implantation genetic diagnosis (PGD) may be used with in vitro (artificial) fertilization. In PGD, embryos are tested for the gene that causes JBS, and only the embryos that do not have those mutations are implanted and brought to term. Because JBS can be detected in a fetus, parents may choose whether to continue the pregnancy. However, this type of predictive genetic testing is considered controversial, and a genetic counselor can assist parents with these difficult decisions.
This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).
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