Updated: Jan 29, 2009
Skeletal dysplasias are a heterogeneous group of dysplasias that include more than 200 recognized conditions. They are disorders of growth and remodeling of bone and cartilage. Most disorders result in short stature, which is defined as height more than 2 standard deviations below the mean for the population at a given age.
Conditions that cause dwarfing are frequently referred to as short-limb or short-trunk types, depending on whether the trunk or limbs are more extensively involved. Diastrophic dysplasia is considered a short-limb dwarfing condition. Additional terms used to describe the segment of the limb with the greatest involvement are rhizomelic (proximal), mesomelic (middle), and acromelic (distal). In diastrophic dysplasia, the extremity involvement is rhizomelic (in 40% of cases) or mesomelic (in 29% of cases) (see Image 1).
A distinct group of patients who have many features of diastrophic dysplasia are referred to as having diastrophic variants; these individuals are taller and less severely affected than persons with classic diastrophic dwarfism. Classic diastrophic dysplasia and diastrophic variants are different expressions of a single genetic disorder (with variable penetrance) rather than separate entities. Individuals identified as having a diastrophic variant should be referred to as having mild diastrophic dysplasia.
Impairment of physeal, epiphyseal, and articular cartilage throughout the body is responsible for characteristic findings. Unlike those with achondroplasia or hypochondroplasia, patients with diastrophic dysplasia have epiphyseal involvement and are at risk for degenerative joint disease. Although the development and growth of cartilaginous structures are disturbed, the intramembranous ossification and appositional growth pattern are not primarily affected.
Although diastrophic dysplasia is extremely rare, the percentage of carriers in certain groups is high. In Finland, 1-2% of the general population are carriers and a total of 183 cases have been diagnosed, with a prevalence of 1 per 30,000 population. Diastrophic dysplasia has been observed in most white populations.
Diastrophic dysplasia is an autosomal recessive disorder and occurs with equal frequency in males and females.
In 1994, Hastbacka et al identified the gene DTDST. This gene, which codes for a sulfate transporter protein, has been mapped to distal end of chromosome bands 5q31-q34.4
DTDST is inherited in an autosomal recessive manner.5 About 5% of cases may involve sporadic new mutations. Both parents of an affected individual are carriers of the abnormal gene but are clinically healthy. For a carrier couple, each pregnancy entails a 25% risk of producing an affected child. Each unaffected full sibling of an affected individual has a 67% likelihood of being a carrier. The offspring of an affected individual is a carrier and therefore unaffected unless the other parent is a carrier or affected with the same condition. Diastrophic dysplasia and McKusick-type metaphyseal chondrodysplasia are the only skeletal dysplasias with autosomal recessive transmission.
Diastrophic dysplasia is a disorder with a wide range of clinical manifestations; this variation has important implications. Parents of a child with mild diastrophic dysplasia, which would previously have been called a diastrophic variant, must be informed that they are at 25% risk of having other children with disproportionate dwarfism. In addition, they should be made aware that the expression of the disorder may be more severe in subsequent children.
Proteoglycans are considered to be among the chief constituents of cartilage. Undersulfation of proteoglycan in the cartilaginous matrix is responsible for the impairment of performance and load-bearing ability of physeal, epiphyseal, and articular cartilage throughout the body.
The DTDST protein acts as a sodium-independent sulfate/chloride transporter and belongs to the SLC26 anion transporter family. The Finnish founder mutation in DTDST has been identified.4 Approximately 95% of affected Finnish patients have a rare ancestral haplotype that was found in only 4% of a Finnish control population. The founder mutation is a guanine-thymine (GT) to guanine-cytosine (GC) transition in the splice donor site of a 5'-untranslated exon of the DTDST gene. The mutation acts by severely reducing levels of mRNA of the DTDST transcript.6
Mutations in DTDST are responsible for a family of chondrodysplasias that include 4 recessively inherited conditions: diastrophic dysplasia, multiple epiphyseal dysplasia, atelosteogenesis type 2, and achondrogenesis type 1B. In addition to the intrinsic sulfate transport properties of the DTDST protein, other factors influence the phenotype in individuals with these mutated alleles.
In evaluating a patient, several aspects of his or her medical history should be investigated for coordination of care. Respiratory difficulties, neurogenic problems, family history, and history of any prior skeletal surgery should be investigated.
The diagnosis can be made at birth with the observation of pathognomic features or within the first few months of life, when the cystic swelling of the ears becomes apparent. Neonates with diastrophic dysplasia may be thought to have atypical achondroplasia at birth, but the diagnosis is relatively easy to establish in the older child or adult because of the unique combination of deformities. Birth length, head circumference, and weight should be recorded. The mental status and intelligence findings are normal.
Height is related to severity of involvement; taller people are less severely affected than shorter people. The mean height is 136 cm in men and 129 cm in women. The pubertal growth spurt is diminished; therefore, the overall growth failure is progressive. The other components of puberty occur normally. This fact suggests that the bones do not respond to hormonal influences. The patient's height percentile for age should be determined by using specific growth charts. In relationship to trunk length, the limbs are relatively short. Short-limbed stature can be confirmed by measurement of the upper-to-lower segment ratio. The normal ratio is 1.6 at birth and decreases to 0.93 during adolescence. Kyphoscoliosis and hip and knee contractures further accentuate the apparent dwarfism. Difficulty in walking is common, and some patients are wheelchair bound.7,8
The expression and severity of diastrophic dysplasia vary greatly. Patients may present with complaints pertaining to the head and neck, spine, major joints, and hands and feet (see Image 1), as described below.
Head and neck
Typical facial features are present in most patients.9 Prominent cheek and circumoral fullness inspired the historical term cherub dwarf. The nasal bridge is narrow, without flattening or depression. Because the eyes are normally spaced, the distance between the bridge of the nose and inner canthus of the eye appears to be increased. In contrast to the bridge, the mid nose is broad. The nostrils flare, and the columella dips low between them. The arch of the palate is wide, and many teeth are visible when the patient smiles. The face has a long, full appearance with a high, broad forehead and square jaw. Midline hemangiomas are sometimes present but fade with age.
Approximately 50% of patients have a cleft palate, either complete or partial. Other abnormalities, such as a high and arched palate, bifid uvula, or submucous clefts, are common. This cleft palate may also contribute to aspiration pneumonia. The cartilage of the larynx and trachea is abnormally soft, and this may contribute to narrowing of respiratory passages. The abnormal palate may play a part in the production of the somewhat characteristic voice heard in patients with this condition. Patients also have a hoarse cry. Hyponasality or misarticulation of R, S, or L sounds is observed in 50% of these patients, possibly due to defects in the palate or vocal cords or due to laryngeal cartilage affection in a process similar to that seen in the ears.10
The pinnae, though unaffected at birth, develop acute swelling at 3-6 weeks of age (see Image 2). The swelling is usually bilateral. The pinnae are reddened, swollen, hot, and often fluctuant; they may feel cystic. After these findings resolve, the cartilage thickens and deforms, giving rise to cauliflower ear, one of the pathognomonic features of diastrophic dysplasia. This typical cauliflower ear is present in 85% of patients. Eventually, the pinnae may become calcified or even ossified. Typically, older patients have rock-hard masses in the superior portions, which are easily palpable.
Spine
One half to one third of patients develop cervical kyphosis. Cervical kyphosis may be present in infancy; its course is variable. Though spontaneous resolution has been reported, the possibility of progression with neurologic involvement should always be considered. Progressive kyphosis of the cervical spine causing quadriplegia with respiratory muscle paralysis and neurogenic bladder has been described in young children.11,12,13,14,15,16
Generally, external signs of cervical abnormalities are absent; however, 80% of patients present with some degree of spinal curvature. Scoliosis is not present at birth, but it tends to develop within the first year of life; it becomes progressively severe with weight bearing. Spinal stenosis is not common, in contrast to its presence in achondroplasia. Mild stenosis may be masked by a patient's relative inactivity. Most patients have significant lumbar lordosis, most likely due to associated hip flexion contracture. Kyphoscoliosis can cause imbalance of the trunk, leading to difficulties in gait and a reduction in already short standing height.
Early and rapid progression of spinal degenerative changes is a normal finding in patients, regardless of age, and leads to stiffness of the cervical spine on physical examination. At present, only one case of atlantoaxial instability has been reported, to the authors' knowledge.
Scoliosis is common. The reported prevalence is 37-88%. Scoliosis can be divided into 3 subtypes: early progressive, idiopathic, and mild nonprogressive (see Image 4). In early progressive scoliosis, dysplastic curves are sharply angular and segment curves are short with associated kyphosis at the same level. Neurologic deficits may be present from severe kyphosis. Lumbar lordosis is usually significant (see Image 5). Spinal stenosis is less common. Degenerative changes are common at all levels, and in patients of all ages. These changes lead to spinal stiffness that is evident on clinical examination.
The hips maintain a persistent flexion contracture. Patients may present with hip subluxation. Arthritic changes develop by early-to-middle adulthood. Hip dysplasia is usually progressive and may result in a significant decrease in the range of motion.17 The knees, too, have flexion contractures. Excessive valgus with lateral dislocation of the patella may occur. Genu valgum with patellar dislocation may occur in patients with diastrophic dysplasia. Genu varum is uncommon. Similar to hip changes, arthritic changes develop by early-to-middle adulthood. Rarely, the patient may manifest joint laxity and instability rather than limitation of motion. The symptoms may involve hips, knees, ankles, shoulders, or elbows.18
In the major joints, motion is markedly limited, and there is a tendency toward dislocation or subluxation. The hips, knees, and elbows are usually affected. At birth, the hips are normal, but with walking, coxa vara becomes apparent, often with subluxation or dislocation of the femoral heads. Bilateral hip dislocations occur in 25% of patients. The proximal femoral epiphyses deform. Hinge abduction may develop in some patients. Valgus may develop at the knee joint, along with subluxation of the patella and flexion contracture. The elbows and shoulders are occasionally subluxated, and the radial head may be dislocated. Degenerative joint disease of the hips and knees develops in early-to-mid adulthood. The joints may be affected by webbing, in addition to the contractures.
Hands and feet
The hands are short, broad, and ulnarly deviated due to shortening of the ulna. The fingers appear widely spaced. About 95% of patients have an abducted, hypermobile, hitchhiker thumb (see Image 3). The first metacarpal is characteristically short, leading to the clinical appearance of proximal insertion of the thumb. Flexion is absent at multiple proximal interphalangeal joints of the fingers. This finding, termed symphalangism, is associated with the absence of normal flexural creases and suggests an antenatal onset.
Other findings
Associated hernia is another possible manifestation of the basic mesodermal defect. Cases of inguinal hernia have been reported in patients with diastrophic dysplasia.
Differential diagnoses for diastrophic dysplasia are as follows:
Consultations should involve the following specialists:
In a large survey of patients with chondrodysplasias, the highest percentage of patients treated surgically were those with diastrophic dysplasia (87.5%). As a part of the same survey, 88.8% of patients judged the outcome after surgery to be an improvement. See Surgical therapy for a discussion of the relevant surgical procedures.
See Clinical.
See Surgical therapy.
The histologic characteristics of the cartilage appear to be similar in the fetus and older patient and therefore may be useful in differentiating diastrophic dysplasia from other osteochondrodysplasias in the second trimester.
The degenerative changes are primarily seen in the resting cartilage. At low magnification, the changes appear as irregular myxoid degeneration with small cystic areas. At higher magnification, the chondrocytes are surrounded by a halo of dense-appearing cartilage matrix. The chondrocytic nuclei are larger than normal, with some lacunae containing 2 nuclei. The chondrocytes appear to be irregularly distributed in the surrounding densely staining matrix. Scattered foci are acellular, and within these foci, residual thickened collagen fibers form an irregular lacy pattern within amorphous material. The physeal growth zones have normal-appearing hypertrophic and proliferating zones with normal columnization.
Nutritional counseling may be appropriate. As a result of progressive contractures, spine deformities, and joint involvement, patients are relatively inactive. Many patients have difficulty in ambulation, and some are wheelchair bound. Obesity can be an issue in patients with decreased activity levels, and dietary therapy should be initiated early in life.
Morbidity occurs due to the following associated conditions:
Patients have a minimally (5%) increased rate of perinatal mortality due to cervical myelopathy or respiratory problems such as aspiration pneumonia and laryngotracheomalacia. Patients with severe spinal deformities are also predisposed to the development of respiratory problems. A lethal form of diastrophic dysplasia has been described that can cause death soon after birth due to cardiorespiratory insufficiency. Overall, life expectancy is not reduced, and patients are able to lead productive lives at work and with their families.
When one discusses height in patients with short stature, the term smaller than average may be substituted for the term dwarf.
The term pseudodiastrophic dwarfism is used for a disorder that clinically, radiologically, and histologically differs from true diastrophic dysplasia, and it should not be used inadvertently.
Lamy M, Maroteaux P. Le nanisme diastrophique. Presse Med. 1960;68:1977-80.
International nomenclature and classification of the osteochondrodysplasias (1997). International Working Group on Constitutional Diseases of Bone. Am J Med Genet. Oct 12 1998;79(5):376-82. [Medline].
International nomenclature of constitutional diseases of bone. Revision, May, 1977. Ann Radiol (Paris). Mar-Apr 1978;21(2-3):253-8. [Medline].
Hastbacka J, Kerrebrock A, Mokkala K. Identification of the Finnish founder mutation for diastrophic dysplasia (DTD). Eur J Hum Genet. Sep 1999;7(6):664-70. [Medline].
Maeda K, Miyamoto Y, Sawai H, Karniski LP, Nakashima E, Nishimura G. A compound heterozygote harboring novel and recurrent DTDST mutations with intermediate phenotype between atelosteogenesis type II and diastrophic dysplasia. Am J Med Genet A. Jun 1 2006;140(11):1143-7. [Medline].
Miyake A, Nishimura G, Futami T, Ohashi H, Chiba K, Toyama Y, et al. A compound heterozygote of novel and recurrent DTDST mutations results in a novel intermediate phenotype of Desbuquois dysplasia, diastrophic dysplasia, and recessive form of multiple epiphyseal dysplasia. J Hum Genet. 2008;53(8):764-8. [Medline].
Qureshi F, Jacques SM, Johnson SF. Histopathology of fetal diastrophic dysplasia. Am J Med Genet. Apr 10 1995;56(3):300-3. [Medline].
Remes V, Poussa M, Lönnqvist T, Puusa A, Tervahartiala P, Helenius I. Walking ability in patients with diastrophic dysplasia: a clinical, electroneurophysiological, treadmill, and MRI analysis. J Pediatr Orthop. Sep-Oct 2004;24(5):546-51. [Medline].
Karlstedt E, Kovero O, Kaitila I. Transverse facial morphology in patients with diastrophic dysplasia. J Craniofac Genet Dev Biol. Oct-Dec 1997;17(4):178-83. [Medline].
Karlstedt E, Isotalo E, Haapanen ML. Correlation between speech outcome and cephalometric dimensions in patients with diastrophic dysplasia. J Craniofac Genet Dev Biol. Jan-Mar 1998;18(1):38-43. [Medline].
Kash IJ, Sane SM, Samaha FJ. Cervical cord compression in diastrophic dwarfism. J Pediatr. Jun 1974;84(6):862-4. [Medline].
Matsuyama Y, Winter RB, Lonstein JE. The spine in diastrophic dysplasia. The surgical arthrodesis of thoracic and lumbar deformities in 21 patients. Spine. Nov 15 1999;24(22):2325-31. [Medline].
Remes V, Tervahartiala P, Poussa M. Thoracic and lumbar spine in diastrophic dysplasia: a clinical and magnetic resonance imaging analysis. Spine. Jan 15 2001;26(2):187-95. [Medline].
Remes V, Marttinen E, Poussa M. Cervical kyphosis in diastrophic dysplasia. Spine. Oct 1 1999;24(19):1990-5. [Medline].
Remes V, Tervahartiala P, Poussa M. Cervical spine in diastrophic dysplasia: an MRI analysis. J Pediatr Orthop. Jan-Feb 2000;20(1):48-53. [Medline].
Remes V, Poussa M, Peltonen J. Scoliosis in patients with diastrophic dysplasia: a new classification. Spine. Aug 1 2001;26(15):1689-97. [Medline].
Vaara P, Peltonen J, Poussa M. Development of the hip in diastrophic dysplasia. J Bone Joint Surg Br. Mar 1998;80(2):315-20. [Medline].
Peltonen J, Vaara P, Marttinen E. The knee joint in diastrophic dysplasia. A clinical and radiological study. J Bone Joint Surg Br. Jul 1999;81(4):625-31. [Medline].
Ryoppy S, Poussa M, Merikanto J. Foot deformities in diastrophic dysplasia. An analysis of 102 patients. J Bone Joint Surg Br. May 1992;74(3):441-4. [Medline].
Weiner DS, Jonah D, Kopits S. The 3-dimensional configuration of the typical foot and ankle in diastrophic dysplasia. J Pediatr Orthop. Jan-Feb 2008;28(1):60-7. [Medline].
Remes VM, Helenius IJ, Marttinen EJ. Manubrium sterni in patients with diastrophic dysplasia--radiological analysis of 50 patients. Pediatr Radiol. Aug 2001;31(8):555-8. [Medline].
Remes V, Tervahartiala P, Helenius I. Magnetic resonance imaging analysis of hip joint development in patients with diastrophic dysplasia. J Pediatr Orthop. Mar-Apr 2002;22(2):212-6. [Medline].
Miller E, Blaser S, Miller S, Keating S, Thompson M, Unger S, et al. Fetal MR imaging of atelosteogenesis type II (AO-II). Pediatr Radiol. Aug 21 2008;[Medline].
Vaara P, Marttinen E, Peltonen J. Ultrasonography of the patellofemoral joint in diastrophic dysplasia. J Pediatr Orthop. Jul-Aug 1997;17(4):512-5. [Medline].
Canto MJ, Buixeda M, Palau J, Ojeda F. Early ultrasonographic diagnosis of diastrophic dysplasia at 12 weeks of gestation in a fetus without previous family history. Prenat Diagn. Oct 2007;27(10):976-8. [Medline].
Canto MJ, Buixeda M, Palau J, Ojeda F. Early ultrasonographic diagnosis of diastrophic dysplasia at 12 weeks of gestation in a fetus without previous family history. Prenat Diagn. Oct 2007;27(10):976-8. [Medline].
Basbug M, Ozgun MT, Serin IS, Akgun H, Dundar M, Kurtoglu S. OC236: Prenatal diagnosis of skeletal dysplasias: 12-year single-center experience. Ultrasound Obstet Gynecol. Oct 2007;30(4):439. [Medline].
Sepulveda W, Sepulveda-Swatson E, Sanchez J. Diastrophic dysplasia: prenatal three-dimensional ultrasound findings. Ultrasound Obstet Gynecol. Mar 2004;23(3):312-4. [Medline].
Hunter AG. Perceptions of the outcome of orthopedic surgery in patients with chondrodysplasias. Clin Genet. Dec 1999;56(6):434-40. [Medline].
Helenius I, Remes V, Tallroth K, Peltonen J, Poussa M, Paavilainen T. Total hip arthroplasty in diastrophic dysplasia. J Bone Joint Surg Am. Mar 2003;85-A(3):441-7. [Medline].
Haila S, Hastbacka J, Bohling T. SLC26A2 (diastrophic dysplasia sulfate transporter) is expressed in developing and mature cartilage but also in other tissues and cell types. J Histochem Cytochem. Aug 2001;49(8):973-82. [Medline].
Horton WA, Hall JG, Scott CI. Growth curves for height for diastrophic dysplasia, spondyloepiphyseal dysplasia congenita, and pseudoachondroplasia. Am J Dis Child. Apr 1982;136(4):316-9. [Medline].
Horton WA, Rimoin DL, Lachman RS. The phenotypic variability of diastrophic dysplasia. J Pediatr. Oct 1978;93(4):609-13. [Medline].
Makitie O, Kaitila I. Growth in diastrophic dysplasia. J Pediatr. Apr 1997;130(4):641-6. [Medline].
Richards BS. Atlanto-axial instability in diastrophic dysplasia. A case report. J Bone Joint Surg Am. Apr 1991;73(4):614-6. [Medline].
Rimoin DL. The chondrodystrophies. Adv Hum Genet. 1975;5:1-118. [Medline].
Walker BA, Scott CI, Hall JG. Diastrophic dwarfism. Medicine (Baltimore). Jan 1972;51(1):41-59. [Medline].
diastrophic dysplasia, classic diastrophic dysplasia, mild diastrophic dysplasia, skeletal dysplasia, diastrophic variants, cherub dwarf, diastrophic dwarfism, dwarfing, diastrophic nanism syndrome, achondroplasia with clubfeet, diastrophic variant, arthrogryposis multiplex congenita, DTDST gene, multiple epiphyseal dysplasia
Shital Parikh, MD, Assistant Professor, Department of Pediatric Orthopaedic Surgery, Cincinnati Children's Hospital Medical Center
Shital Parikh, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Medical Association, and Orthopaedic Research Society
Disclosure: Nothing to disclose.
Preeti Batra, MBBS, MD, Staff Physician, Department of Radiology, VS Hospital, India
Disclosure: Nothing to disclose.
Twee Do, MD, Assistant Professor, Department of Pediatric Orthopedic Surgery, University of Cincinnati College of Medicine; Director, Neuromuscular Orthopedic Services, Cincinnati Children's Hospital Medical Center
Twee Do, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons and American Academy of Pediatrics
Disclosure: Nothing to disclose.
Howard A Chansky, MD, Associate Professor, Department of Orthopedics and Sports Medicine, University of Washington Medical Center
Howard A Chansky, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons
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Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
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Sean P Scully, MD, PhD, Professor, Department of Orthopedics, University of Miami
Sean P Scully, MD, PhD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, International Society on Thrombosis and Haemostasis, and Society of Surgical Oncology
Disclosure: Nothing to disclose.
Dinesh Patel, MD, FACS, Associate Clinical Professor of Orthopedic Surgery, Harvard Medical School; Chief of Arthroscopic Surgery, Department of Orthopedic Surgery, Massachusetts General Hospital
Dinesh Patel, MD, FACS is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Association of Physicians of Indian Origin, American College of International Physicians, and American College of Surgeons
Disclosure: Nothing to disclose.
Harris Gellman, MD, Consulting Surgeon, Broward Hand Center; Voluntary Clinical Professor of Orthopedic Surgery and Plastic Surgery, Departments of Orthopedic Surgery and Surgery, University of Miami School of Medicine
Harris Gellman, MD is a member of the following medical societies: American Academy of Medical Acupuncture, American Academy of Orthopaedic Surgeons, American Orthopaedic Association, American Society for Surgery of the Hand, and Arkansas Medical Society
Disclosure: Nothing to disclose.
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Neurofibromatosis Type 1 (NF1) and Tibial Dysplasia
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