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Schwartz Jampel Syndrome

NORD is very grateful to Phillip L. Pearl, MD, Division Chief, Child Neurology, Children's National Medical Center; Professor of Pediatrics and Neurology, The George Washington University School of Medicine, for assistance in the preparation of this report.

Synonyms of Schwartz Jampel Syndrome

  • chondrodystrophic myotonia
  • myotonic myopathy, dwarfism, chondrodystrophy, ocular & facial anomalies
  • Schwartz-Jampel-Aberfeld syndrome
  • SJA syndrome
  • SJS

Disorder Subdivisions

  • Schwartz-Jampel syndrome, type 2
  • Schwartz-Jampel syndrome, types 1A and 1B

General Discussion

Schwartz-Jampel syndrome (SJS) is a rare genetic disorder characterized by abnormalities of the skeletal muscles, including muscle weakness and stiffness (myotonic myopathy); abnormal bone development (bone dysplasia); permanent bending or extension of certain joints in a fixed position (joint contractures); and/or growth delays resulting in abnormally short stature (dwarfism). Affected individuals may also have small, fixed facial features and various abnormalities of the eyes, some of which may cause impaired vision. The range and severity of symptoms may vary from case to case. Two types of the disorder have been identified that may be differentiated by age of onset and other factors. SJS type 1, which is considered the classical form of the disorder, may become apparent during early to late infancy or childhood. SJS type 2, a more rare form of the disorder, is typically recognized at birth (congenital). Most researchers now believe that SJS type 2 is actually the same disorder as Stuve-Wiedemann syndrome and not a form of SJS. (For more information on Stuve-Wiedemann syndrome see the Related Disorders section of this report.)

SJS is thought to be inherited as an autosomal recessive trait. However, some cases reported in the medical literature suggest an autosomal dominant inheritance pattern.

Symptoms

SJS is primarily characterized by abnormalities of skeletal muscle, bone, and cartilage; malformations of the eyes and the face; and growth delays. In some cases, additional abnormalities may also be present. The range and severity of associated symptoms and physical findings varies from case to case, depending upon the form of the disorder present and other factors. Two forms of the disorder have been recognized, which are known as SJS types 1 and 2. SJS type 1, which is considered the classical form of the disorder, may be recognized during early to late infancy or childhood, whereas SJS type 2 is apparent at birth (congenital).

Infants with classical or type 1 SJS may have a normal or low birth weight. From the first or second year of life through childhood, an affected child's growth rate may be below the normal range. Although the growth rate may increase during puberty, adult height may still be below the normal range; as a result, such affected individuals may have abnormally short stature (dwarfism). In addition to possible growth delays, most infants with SJS are delayed in reaching developmental milestones, such as crawling, sitting, walking, etc. (delayed motor development). However, after the age of about two years, their motor abilities may improve. Mental development is generally normal.

The skeletal muscle abnormalities associated with SJS may be recognized at birth or infancy or may become apparent within the second year of life. Affected children may have muscle stiffness and weakness, an inability to relax certain muscles after they have contracted (myotonic myopathy), and abnormally small skeletal muscles. In addition, several joints may become fixed in a permanently bent or extended position (joint contractures) due to shortening of muscle fibers. In some cases, the symptoms of myotonic myopathy associated with SJS may gradually diminish.

In most cases, individuals with classical SJS also have abnormalities of bone and cartilage growth (chondrodystrophy). The layers of cartilage that separate the shaft of a long bone (diaphysis) from its growing end (epiphyseal plate or growth plate) may develop abnormally (epiphyseal dysplasia). (Long bone refers to bones in the arms and legs.) As a result, the growing end (epiphysis) of the long bone may flatten and fragment. Such flattening of the epiphysis of the thighbone (femur) may contribute to or occur in association with abnormal development of the hipbone (hip dysplasia).

Additional skeletal abnormalities may also occur in children with classical Schwartz-Jampel syndrome. Affected individuals may have an abnormally short neck, malformation of the hip (hip dysplasia), and/or a sideways and front-to-back curvature of the spine (kyphoscoliosis). In addition, the breastbone (sternum) may be abnormally prominent ("pigeon breast" or pectus carinatum).

Some researchers suggest that the classical form of SJS may be divided into two distinct subgroups, depending upon the severity of associated skeletal abnormalities. SJS type 1A, which may be recognized during early childhood, is characterized by mild skeletal changes (skeletal dysplasia) that occur secondary to skeletal muscle abnormalities. Type 1B may be recognized at birth or early infancy based upon primary, more pronounced abnormalities of bone development (primary skeletal dysplasia) in association with muscle defects.

Many of the musculoskeletal abnormalities occurring in association with classical SJS (e.g., myotonia, joint contractures, hip dysplasia, etc.) may make it difficult for affected individuals to perform certain voluntary movements. For example, many may have difficulty walking independently.

Within the first or second year of life, facial abnormalities associated with classical SJS also become apparent. The mouth and chin may appear abnormally small; the face may appear flat; facial expressions may seem fixed or mask-like; and the face may have a characteristic "pinched" appearance. In addition, the entire face may seem small in relation to the size of the head. Affected individuals may also have abnormally low-set ears.

Many individuals with classical SJS also have several eye (ocular) abnormalities. The front transparent region of the eye through which light passes may be small (microcornea) or the entire eye may appear unusually small (microphthalmia). The opening between the upper and lower eyelids (palpebral fissures) may be narrow and short (blepharophimosis), and the lids may have two or more rows of eyelashes. Affected individuals may also have nearsightedness (myopia), clouding of the lenses of the eyes (juvenile cataracts), and/or intermittent, involuntary contractions or spasms of the muscles around the eyes (blepharospasm). Such eye abnormalities may result in varying degrees of visual impairment. In cases of blepharospasm, an inability to open the eyelids due to involuntary muscle spasms may result in functional blindness. The degree of visual impairment in affected individuals depends upon the severity and/or combination of eye abnormalities present. (For more information on blepharospasm, please see the Related Disorders section below.)

In some cases, individuals with classical SJS may have additional abnormalities. Affected individuals may have high-pitched voices and their speech may be difficult to understand. In some cases, there may be protrusion of portions of the large intestine through an abnormal opening in muscles of the groin (inguinal hernia) or the abdominal wall where the umbilical cord joins the fetal abdomen (umbilical hernia). In addition, some affected males may have unusually small testes. Individuals with the disorder may also be prone to repeated respiratory infections.

Some individuals with SJS may be at risk for malignant hyperthermia, a condition in which exposure to certain anesthetics or muscle relaxants may cause a sudden rise in body temperature (hyperthermia), muscle twitching and stiffness, and other symptoms. Without appropriate treatment, life-threatening symptoms may result. (For more information on this condition, please see the Related Disorders section of this report.)

As mentioned above, researchers have recognized a second, more severe form of Schwartz-Jampel syndrome, known as SJS type 2. Because this form of the disorder is apparent at birth, it is also often referred to as "neonatal" SJS. SJS type 2 is characterized by distinctive facial abnormalities, including a "pursed" appearance of the mouth; muscle weakness; and abnormalities of the growing ends of the long bones (metaphyses) of the arms and legs (limbs), associated bowing of the limbs (campomelic-metaphyseal skeletal dysplasia), and short stature. Additional findings typically include permanent bending or extension of several joints in various fixed postures (joint contractures) at birth. Affected infants may also have feeding, swallowing, and breathing difficulties and be prone to sudden and severe rises in body temperature (hyperthermia), potentially leading to life-threatening complications. Many researchers suggest that SJS type 2 and a disorder known as Stuve-Wiedemann syndrome are the same disease entity.

Causes

SJS types 1 and 2 are both thought to have autosomal recessive inheritance. Genetic diseases are determined by two genes, one received from the father and one from the mother.

Recessive genetic disorders occur when an individual inherits the same abnormal gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk for two carrier parents to both pass the defective gene and, therefore, have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%.

Some individuals with SJS types 1 and 2 have had parents who were related by blood (consanguineous). All individuals carry 4-5 abnormal genes. Parents who are close relatives (consanguineous) have a higher chance than unrelated parents to both carry the same abnormal gene, which increases the risk to have children with a recessive genetic disorder.

Researchers have determined that the classical form of SJS may be caused by changes (mutations) of a gene encoding perlecan located on the short arm (p) of chromosome 1 (1p36.1-p34). Perlecan is a large heparan sulfate proteoglycan and plays a role in neuromuscular function and cartilage formation. Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males, and two X chromosomes for females. Each chromosome has a short arm designated as "p" and a long arm identified by the letter "q." Chromosomes are further subdivided into many bands that are numbered.

Genetic evaluation of at least three families (kindreds) with individuals affected by the severe neonatal form of SJS (type 2) has determined that those with the disorder did not have mutations of the disease gene located at 1p36.1-p34 (discussed above). Accordingly, researchers indicate that SJS may result from mutations of different genes (genetic heterogeneity).

Affected Populations

SJS (SJS) types 1 and 2 are rare disorders that appear to affect males and females in equal numbers. More than 85 cases have been reported in the medical literature, including individuals affected by the classical (type 1) and the more severe neonatal form (type 2) of the disorder. SJS type 2 appears to be most common in individuals of United Arab Emirates descent. Depending upon the form of the disorder present, associated symptoms and findings may be recognized at birth or may become apparent during infancy or within the second year of life.

Related Disorders

Symptoms of the following disorders may be similar to those of SJS. Comparisons may be useful for a differential diagnosis:

Stuve-Wiedemann syndrome is a rare skeletal disorder present at birth (congenital). It is characterized by short stature, bowing of the long bones of the arms and legs (campomelia), and fingers or toes that are permanently flexed (camptodactyly) outward away from the thumb (ulnar deviation). Affected infants may develop life-threatening complications such as episodes where there is a sudden rise in body temperature (hyperthermia) or respiratory distress. Stuve-Wiedemann syndrome is inherited as an autosomal recessive trait. Some researchers believe that Stuve-Wiedemann syndrome and SJS type II are the same disorder. SJS was previously believed to be the newborn (neonatal) form of SJS. However, the clinical and radiographic pictures of Stuve-Wiedemann and SJS type II are nearly identical leading many researchers to believe the two disorders are a single entity. (For more information on this disorder, choose "Stuve-Wiedemann" as your search term in the Rare Disease Database.)

Freeman-Sheldon syndrome, also known as craniocarpotarsal dystrophy, is a rare inherited disorder characterized by a flattened, masklike face; deep-set eyes; a slightly shortened opening between the upper and lower eyelids (blepharophimosis); full cheeks; a small mouth (microstomia) that has a "whistling" appearance; and other craniofacial abnormalities. Skeletal abnormalities may also be present, such as a short neck, fingers that are permanently flexed (camptodactyly), and/or a foot that is twisted out of shape (club foot or talipes equinovarus). Freeman-Sheldon syndrome is inherited as an autosomal dominant genetic trait. (For more information on this disorder, choose "Freeman-Sheldon" as your search term in the Rare Disease Database.)

Marden-Walker syndrome is a rare connective tissue disorder that is inherited as an autosomal recessive genetic trait. Affected individuals may exhibit abnormalities of the head and facial (craniofacial) area including a masklike face, a flat nasal bridge, a small jaw (micrognathia), droopy upper eyelids (ptosis), an abnormally narrow opening between the upper and lower eyelids (blepharophimosis), and/or low-set ears. Individuals with Marden-Walker syndrome may also exhibit incomplete closure of the roof of the mouth (cleft palate) and/or a vertical groove in the upper lip (cleft lip). In addition, affected individuals may exhibit growth delay, reduced muscle mass, joints that are in a fixed position (joint contractures), and/or limited control of muscle movement. In some cases, skeletal abnormalities may be present, such as a sideways (scoliosis) or front-to-back curvature of the spine (kyphosis) and/or a breast bone that is abnormally prominent (pigeon breast or pectus carinatum) or appears to sink inward (funnel chest or pectus excavatum). (For more information on this disorder, choose "Marden-Walker" as your search term in the Rare Disease Database.)

Morquio syndrome, also known as mucopolysaccharidosis IV (MPS IV), exists in two forms (Morquio syndromes A and B), due to a deficiency of the enzyme N-acetyl-galactosamine-6-sulfatase and beta-galactosidase, respectively. A deficiency of either enzyme leads to the accumulation of keratan sulfate in the body, abnormal musculoskeletal development, and other symptoms. The clinical features of MPS IV-B are usually fewer and milder than those associated with MPS IV-A. Symptoms may include growth retardation, a prominent lower face, an abnormally short neck, knees that are abnormally close together (knock knees or genu valgum), flat feet, a sideways and front-to-back curvature of the spine (kyphoscoliosis), abnormal development of the growing ends of the long bones (epiphyses), and/or a prominent breast bone (pectus carinatum). Hearing loss, weakness of the legs, and/or other abnormalities also often occur. Morquio syndromes A and B are inherited as autosomal recessive genetic traits. (For more information on these disorders, choose "Morquio" as your search term in the Rare Disease Database.)

King syndrome, an extremely rare disorder, is a form of malignant hyperthermia. Exposure to certain anesthetics or muscle relaxants may cause a sudden rise in an affected individual's body temperature, muscle stiffness, and other symptoms. (For more information, see "malignant hyperthermia" below.) Individuals with King syndrome also exhibit several characteristic physical abnormalities. These include abnormalities of the head and facial (craniofacial) area, such as low-set ears and/or incomplete development of the middle portion of the face (midface hypoplasia). In addition, the upper eyelids may droop (ptosis) and the opening between the upper and lower eyelids (palpebral fissures) may slant downward. Skeletal abnormalities may also be present, including a sideways and front-to-back curvature of the spine (kyphoscoliosis), abnormally short stature, and/or an unusually prominent breastbone (pigeon breast or pectus carinatum). In some cases, mild muscle weakness may be present, and/or certain joints may be fixed in a permanently flexed position due to shortening of muscle fibers (joint contractures). King syndrome is believed to result from a spontaneous genetic change that occurs for unknown reasons (sporadic); in addition, some researchers believe that King syndrome may be inherited as an autosomal recessive trait.

Van Dyke-Hanson syndrome is a rare inherited neuromuscular disorder. In some cases, affected individuals may exhibit permanently flexed, fixed joints in the hands and feet at birth (congenital joint contractures). During early childhood, those with the disorder may begin to experience one- to two-minute attacks characterized by impaired coordination of voluntary movement (periodic ataxia) affecting the central part of the body (trunk) and/or the head (titubation); in addition, affected individuals may also experience uncontrolled jerking movements of the arms, legs, and head during the attacks. Such episodes may be triggered by abrupt changes in posture, events that bring on a strong emotional response, and/or other factors. The disorder may also be characterized by short, spontaneous spasms and contractions within groups of muscle fibers (myokymia) in the facial area, arms, and legs. Continuous electrical activity is apparent within muscle fibers, even while at rest. It is believed that Van Dyke-Hanson syndrome is inherited as an autosomal dominant trait.

The following disorders may be associated with SJS as secondary characteristics. They are not necessary for a differential diagnosis:

Malignant hyperthermia (MH) is a group of inherited disorders in which exposure to certain anesthetics (e.g., halothane or cyclopropane) or particular muscle relaxants (e.g., succinylcholine) may cause a dangerous, sudden rise in body temperature (hyperthermia), muscle twitching and stiffness, headache, nausea, vomiting, low blood pressure (hypotension), rapid heart beat (tachycardia) and/or irregular heartbeat (cardiac arrhythmias). Without appropriate treatment, life-threatening symptoms may result. In some cases, a predisposition to malignant hyperthermia may be inherited as an autosomal dominant genetic trait; in this form, individuals may exhibit no symptoms or physical abnormalities between MH episodes. Other forms of malignant hyperthermia may occur spontaneously and/or be inherited as an autosomal recessive genetic trait (see "King Syndrome" above). Researchers believe that malignant hyperthermia may be caused by the interaction of many genes, possibly in combination with environmental factors (multifactorial inheritance). (For more information on this condition, choose "malignant hyperthermia" as your search term in the Rare Disease Database.)

Blepharospasm is a condition characterized by intermittent, involuntary contractions or spasms of the muscles around the eyes. An inability to open the eyelids due to the involuntary muscle spasms may result in functional blindness. Blepharospasm may be due to an abnormal tissue change (lesion) of the eye; impairment of one of the nerves that arises from the brain and innervates the eyes [trigeminal (5th cranial) nerve]; or psychological stress or may occur due to or in association with a number of different underlying disorders. (For more information on this condition, use "blepharospasm" as your search term in the Rare Disease Database.)

Standard Therapies

Diagnosis
In rare cases, SJS may be diagnosed before birth (prenatally) through the use of specialized tests such as ultrasound. During ultrasonography, reflected sound waves are used to create an image of the developing fetus. Such imaging studies may reveal characteristic findings that suggest SJS or other developmental abnormalities in the fetus.

SJS is usually diagnosed at birth or within the first or second year of life. Such a diagnosis may be confirmed based upon a thorough clinical evaluation, a detailed patient history, and a variety of specialized tests. The presence of myotonic myopathy, a primary finding associated with the disorder, may be confirmed through several tests, including electromyograms (EMG). An EMG is a test that records electrical activity in skeletal muscles at rest and during muscle contraction. In cases of myotonic myopathy, an EMG may demonstrate continuous electrical activity within muscle fibers, even while at rest. Other specialized tests used to confirm myotonic myopathy may include studies that measure the levels of certain enzymes in the fluid portion of the blood (serum enzymes) and/or the surgical removal (biopsy) and microscopic examination (light and/or electron microscopy) of small samples of muscle tissue. The presence of skeletal abnormalities often associated with SJS may be confirmed by specialized imaging studies and other testing.

Treatment
The treatment of SJS is directed toward the specific symptoms that are apparent in each individual. Pediatricians; physicians who diagnose and treat diseases of the eye (ophthalmologists); specialists who diagnose and treat skeletal abnormalities (orthopedists); surgeons; physical therapists; and/or other health care professionals may need to work together to ensure a comprehensive approach to treatment.

Specific therapies for the treatment of SJS are symptomatic and supportive. In some infants with the severe neonatal form of the disorder (SJS Type 2), treatment may require special supportive therapies to ensure the appropriate intake of nutrients, oxygen therapy, measures to help prevent or appropriately treat episodes of hyperthermia, and other therapies as required.

In individuals with SJS, various orthopedic techniques, including surgery, may be used to help treat and/or correct musculoskeletal abnormalities, such as joint contractures, kyphoscoliosis, and/or hip dysplasia. Because the skeletal changes associated with hip dysplasia may worsen during childhood, early orthopedic treatment may be essential in preventing such a progression of symptoms. In some cases of hip dysplasia, an artificial device (prosthetic) may be used to replace the hip joint. Physical therapy in combination with such surgical and supportive measures may improve an affected individual's ability to walk and perform other movements independently (mobility). In addition, in some individuals with SJS, depending upon the visual abnormalities that are present, corrective glasses, contact lenses, other supportive methods, and/or surgery may be used to help improve vision.

Additional therapeutic and/or supportive measures may be necessary in some cases. Physicians may regularly monitor affected individuals and recommend preventive measures for those who may be prone to respiratory infections. In individuals with protrusion of portions of the large intestine through an abnormal opening in muscles of the groin (inguinal hernia), surgical correction of the hernia may be necessary. If there is a small, abnormal opening in muscles of the abdominal wall where the umbilical cord joined the fetal abdomen (umbilical hernia), the abnormal opening may close on its own (spontaneously) within one or two years; however, if the umbilical hernia is large, surgery may be required.

Some individuals with SJS may be at risk for Malignant Hyperthermia when exposed to certain anesthetics or muscle relaxants. This risk must be taken into consideration by surgeons, anesthesiologists, dentists, and other health care workers when making decisions concerning potential surgery and use of particular anesthetics. It must also be considered by primary care physicians and other health professionals when prescribing certain medications.

Early intervention is important in ensuring that children with SJS reach their potential. Special services that may be beneficial to affected children may include special remedial education, speech therapy, and other medical, social, and/or vocational services.

Genetic counseling will be of benefit for affected individuals and their families. Other treatment is symptomatic and supportive.

Investigational Therapies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:
www.centerwatch.com

Organizations related to Schwartz Jampel Syndrome

(Please note that some of these organizations may provide information concerning certain conditions potentially associated with this disorder [e.g., visual handicaps, short stature, risk for malignant hyperthermia, etc.].)

References

TEXTBOOKS
Snook RJ and Pascuzzi RM. Schwartz-Jampel Syndrome. In: NORD Guide to Rare Disorders. Philadelphia, PA: Lippincott Williams & Wilkins; 2003:586-87.

Fauci AS, et al., eds. Harrison's Principles of Internal Medicine, 14th Ed. New York, NY: McGraw-Hill, Inc; 1998:2476.

Jones KL, ed. Smith's Recognizable Patterns of Human Malformation. 5th ed. Philadelphia, PA: W. B. Saunders Co: 1997:186.

Behrman RE, ed. Nelson Textbook of Pediatrics, 15th ed. Philadelphia, PA: W.B. Saunders Company; 1996:1750.

Menkes JH, au., Pine JW, et al., eds. Textbook of Child Neurology, 5th ed. Baltimore, MD: Williams & Wilkins; 1995:838.

Buyce ML, ed. Birth Defects Encyclopedia. Dover, MA: Blackwell Scientific Publications; For: The Center for Birth Defects Information Services Inc; 1990:321-2, 871-2, 1013-4, 1103-04.

JOURNAL ARTICLES
Ho NC, et al. Clinico-pathogenetic findings and management of chondrodystrophic myotonia (Schwartz-Jampel syndrome): a case report. BMC Neurology. 2003;3:3.

Arikawa-Hirasawa E, et al. Structural and functional mutations of the perlecan gene cause Schwartz-Jampel syndrome, with myotonic myopathy and chondrodysplasia. Am J Hum Genet. 2002;70:1368-75.

Cormier-Daire V, et al. Clinical homogeneity of the Stuve-Wiedemann syndrome and overlap with the Schwartz-Jampel syndrome type 2. Am J Med Genet. 1998;78:146-49.

Superti-Furga A, et al. Schwartz-Jampel syndrome type 2 and Stuve-Wiedemann syndrome: a case for "lumping.” Am J Med Genet. 1998;78:150-54.

Giedion A, et al. Heterogeneity in Schwartz-Jampel chondrodystrophic myotonia. Eur J Pediatr. 1997;156:214-23.

Pinto-Escalante D, et al. Identical twins with the classical form of Schwartz-Jampel syndrome. Clin Dysmorphol. 1997;6:45-49.

Brown KA, et al. Genetic heterogeneity in Schwartz-Jampel dyndrome: two families with neonatal Schwartz-Jampel syndrome do not map to human chromosome 1p34-p36.1. J Med Genet. 1997;34:685-87.

Al-Gazali LI, et al. Neonatal Schwartz-Jampel syndrome: a common autosomal recessive syndrome in the United Arab Emirates. J Med Genet. 1996;33:203-11.

Nicole S, et al. Localization of the Schwartz-Jampel syndrome (SJS) locus to chromosome 1p34-p36.1 by homozygosity mapping. Hum Mol Genet. 1995;4:1633-66.

Ray S, et al. Anaesthesia in a child with Schwartz-Jampel syndrome. Anaesthesia. 1994;49:600-02.

Topaloglu H, et al. Improvement of myotonia with carbamazepine in three cases with the Schwartz-Jampel syndrome. Neuropediatrics. 1993;24:232-34.

Al Gazali LI, The Schwartz-Jampel syndrome. Clin Dysmorphol. 1993;2:47-54.

Ben Becher S, et al. Schwartz-Jampel syndrome (osteochondromuscular dystrophy). Arch Fr Pediatr. 1992;49:799-802.

Viljoen D, et al. Schwartz-Jampel syndrome (chondrodystrophic myotonia). J Med Genet. 1992;29:58-62.

Ben Hamida M, et al. Schwartz-Jampel syndrome. Clinical and histopathological study of 4 cases. Rev Neurol. 1991;147:279-84.

Spaans F, et al. Procainamide therapy, physical performance and energy expenditure in the Schwartz-Jampel syndrome. Neuromuscul Disord. 1991;1:371-74.

Spaans F, et al. Schwartz-Jampel syndrome: I. Clinical, electromyographic, and histologic studies. Muscle Nerve. 1990;13:516-27.

Hunziker UA, et al. Prenatal diagnosis of Schwartz-Jampel syndrome with early manifestation. Prenat Diagn. 1989;9:127-31.

Vanlieferighen P, et al. Value of muscle studies in the early diagnosis of Schwartz-Jampel syndrome. J Genet Hum. 1987; 35:243-49.

Farrell S, et al. Neonatal manifestations of Schwartz-Jampel syndrome. Am J Med Genet. 1987;27:799-805.

Edwards WE, et al. Chondrodystrophic myotonia (Schwartz-Jampel syndrome): report of a new case and follow-up of patients initially reported in 1969. Am J Med Genet. 1982;13:51-56.

Hanson PA, et al. Contractures, continuous muscle discharges, and titubation. Ann Neurol. 1977;1:120-24.

Van Dyke DH, et al. Hereditary myokymia and periodic ataxia. J Neurol Sci. 1975;25:109-18.

Aberfeld DC, et al. Chondrodystrophic myotonia: report of two cases. Myotonia, dwarfism, diffuse bone disease, and unusual ocular and facial abnormalities. Arch Neurol. 1970;22:455-62.

INTERNET
Online Mendelian Inheritance in Man (OMIM). The Johns Hopkins University. Schwartz-Jampel Syndrome, Type 1; SJS1. Entry No: 255800. Last Edited September 9, 2010. Available at: http://www.ncbi.nlm.nih.gov/omim/. Accessed September 24, 2012.

Online Mendelian Inheritance in Man (OMIM). The Johns Hopkins University. Stuve-Wiedemann Syndrome. Entry No: 601559. Last Edited April 13, 2009. Available at: http://www.ncbi.nlm.nih.gov/omim/. Accessed September 24, 2012.

The information in NORD’s Rare Disease Database is for educational purposes only. It should never be used for diagnostic or treatment purposes. If you have questions regarding a medical condition, always seek the advice of your physician or other qualified health professional. NORD’s reports provide a brief overview of rare diseases. For more specific information, we encourage you to contact your personal physician or the agencies listed as “Resources” on this report.

Report last updated: 2012/10/11 00:00:00 GMT+0

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