Spondyloepiphyseal dysplasia is a rare hereditary disorder characterized by growth deficiency, spinal malformations, and, in some cases, ocular abnormalities.
Description
Spondyloepiphyseal dysplasia is one of the most common causes of short stature. There are two forms of spondyloepiphyseal dysplasia. Both forms are inherited and both forms are rare.
Congenital spondyloepiphyseal dysplasia
Treatment is mostly symptomatic, and may include:
Orthopedic care throughout life. Early surgical interventional may be needed to correct clubfoot and/or cleft palate. Hip, spinal, and knee complications may occur, and hip replacement is sometimes warranted in adults. Additionally, arthritis may develop due to poorly developed type II collagen. Spinal fusion may be indicated if evaluation of the cervical vertebrae C1 and C2 detects odontoid hypoplasia. If the odontoid is hypoplastic or small, it may predispose to instability and spinal cord compression in congenital spondyloepiphyseal dysplasia).
Ophthalmologic examinations are important for the prevention of retinal detachment and treatment of myopia and early retinal tears if they occur.
Hearing should be checked and ear infections should be closely monitored. Tubes may need to be placed in the ear.
Due to neck instability, persons with SEDC should exercise caution to avoid activities/sports that could result in trauma to the neck or head.
Individuals with congenital spondyloepiphyseal dysplasia should be closely monitored during anesthesia and for complications during a respiratory infection. In particular, during anesthesia, special attention is required to avoid spinal injury resulting from lax ligaments causing instability in the neck. This condition may also result in spinal injury in contact sports and car accidents. Chest constriction may also cause decreased lung capacity.
Orthopedic care may be needed at different times throughout life. Bone changes of the femoral head often lead to secondary osteoarthritis during adulthood and some patients require total replacement of the hip before the age of 40 years.
Some individuals with short stature resulting from spondyloepiphyseal dysplasia may consider limb-lengthening surgery. This is a controversial surgery that lengthens leg and arm bones by cutting the bones, constructing metal frames around them, and inserting pins into them to move the cut ends apart. New bone tissue fills in the gap. While the surgery can be effective in lengthening limbs, various complications may occur.
Genetic profile
Both forms of the disorder are inherited, however they are inherited differently.
Demographics
It has been estimated that spondyloepiphyseal dysplasia affects about one in 100,000 individuals.
Congenital spondyloepiphyseal dysplasia affects both males and females. Spondyloepiphyseal dysplasia tarda affects mostly males.
Diagnosis
X rays may be used to diagnose spondyloepiphyseal dysplasia when it is suspected.
In congenital spondyloepiphyseal dysplasia, only one parent needs to be a carrier in order for the child to inherit the disorder. A child has a 50% chance of having the disorder if one parent has the disorder and a 75% chance of having the disease if both parents have congenital spondyloepiphyseal dysplasia.
In spondyloepiphyseal dysplasia tarda, if a mother has a male child, he has a 50% chance of inheriting the disease-causing gene. A male who inherits an X-linked recessive disorder is affected, and all of his daughters will be carriers, but none of his sons.
Prenatal testing
Prenatal testing may be available to couples at risk for bearing a child with spondyloepiphyseal dysplasia. Testing for the genes responsible for congenital spondyloepiphyseal dysplasia and spondyloepiphyseal dysplasia tarda is possible. Congenital spondyloepiphyseal dysplasia testing may be difficult, however, since although the gene has been located, there is variability in the mutations in the gene amongst persons with the disorder.
Either chorionic villus sampling (CVS) or amniocentesis may be performed for prenatal testing. CVS is a procedure to obtain chorionic villi tissue for testing. Examination of fetal tissue can reveal information about the defects that lead to spondyloepiphyseal dysplasia. Chorionic villus sampling can be performed at 10–12 weeks gestation.
Amniocentesis is a procedure that involves inserting a thin needle into the uterus, into the amniotic sac, and withdrawing a small amount of amniotic fluid. DNA can be extracted from the fetal cells contained in the amniotic fluid and tested. Amniocentesis is performed at 16–18 weeks gestation.
Treatment and management
Individuals with spondyloepiphyseal dysplasia should be under routine health supervision by a physician who is familiar with the disorder, its complications, and its treatment.
Prognosis
Prognosis is variable dependent upon severity of the disorder. Generally, congenital spondyloepiphyseal dysplasia is more symptomatic than spondyloepiphyseal dysplasia tarda. Neither form of the disorder generally leads to shortened life span. Cognitive function is generally normal.
BOOKS
Medical Genetics, edited by Lynn B. Jorde, et al. 2nd ed. St. Louis: Mosby, 1999.
PERIODICALS
Gecz, J., et al. "Gene Structure and Expression Study of the SEDL Gene for Spondyloepiphyseal Dysplasia Tarda." Genomics 69 (2000): 242-51.
Gedeon, A.K., et al. "Identification of the Gene (SEDL) Causing X-linked Spondyloepiphyseal Dysplasia Tarda." Nature Genetics 22 (1999): 400-404.
ORGANIZATIONS
Human Growth Foundation. 997 Glen Cove Ave., Glen Head, NY 11545. (800) 451-6434. Fax: (516) 671-4055. <http://www.hgf1@hgfound.org>.
Little People of America, Inc. National Headquarters, PO Box 745, Lubbock, TX 79408. (806) 737-8186 or (888) LPA-2001. lpadatabase@juno.com. <http://www.lpaonline.org>.
Little People's Research Fund, Inc. 80 Sister Pierre Dr., Towson, MD 21204-7534. (410) 494-0055 or (800) 232-5773. Fax: (410) 494-0062. <http://pixelscapes.com/lprf>.
MAGIC Foundation for Children's Growth. 1327 N. Harlem Ave., Oak Park, IL 60302. (708) 383-0808 or (800) 362-4423. Fax: (708) 383-0899. mary@magicfoundation.org. <http://www.magicfoundation.org/ghd.html>.
Short Stature Foundation. 4521 Campus Drive, #310, Irvine, CA 92715. (714) 559-7131 or (800) 243-9273.
