Updated: 6/17/2021

Diastrophic Dysplasia

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https://upload.orthobullets.com/topic/4097/images/Clinical photo_moved.jpg
https://upload.orthobullets.com/topic/4097/images/cauliflower ear - colorado_moved.jpg
https://upload.orthobullets.com/topic/4097/images/hitchhikers thumb - colorado_moved.jpg
https://upload.orthobullets.com/topic/4097/images/Cervical kyphosis_moved.jpg
https://upload.orthobullets.com/topic/4097/images/Clubfeet_moved.jpg
  • summary
    • Diastrophic Dysplasia is a rare congenital disorder caused by an autosomal recessive mutation in the DTDST gene leading to a defect in the sulfate transporter protein. Patients present with a form of short-limbed dwarfism with characteristic features such as cauliflower ears, hitchhiker thumbs, and severe cervical kyphosis. 
    • Diagnosis is made based on family history associated with typical radiographic and clinical features. No commercially available diagnostic test exists due to the variety of genetic mutations.
    • Treatment involves a multidisciplinary approach to improve and maintain function. Surgical spinal instrumentation and fusion are indicated in patients with atlantoaxial instability, cervical myelopathy, or progressive scoliosis.
  • Epidemiology
    • Demographics 
      • more common in Finland
        • rare in rest of world
  • Etiology
    • Genetics
      • autosomal recessive
      • mutation in DTDST gene (SLC26A2) on chromosome 5
        • encodes for sulfate transporter protein
        • mutation is present in 1 in 70 Finnish citizens
        • leads to undersulfation of cartilage proteoglycan
  • Presentation
    • Physical exam and syndrome features
      • short stature ("twisted dwarf")
        • rhizomelic shortening
      • cleft palate (60%)
      • cauliflower ears (80%)
      • poorly developed UE
      • hitchhikers thumb
      • thoracolumbar scoliosis
      • severe cervical kyphosis
      • hip and knee contractures
      • genu valgum
      • skewfoot (serpentine or Z foot)
        • tarsometatarsal adductus and valgus hindfoot
      • rigid clubfeet (equinocavovarus)
  • Imaging
    • Radiographs
      • recommended views
        • AP and lateral of cervical spine and thoracolumbar spine
        • three joint standing lower extremity films to assess alignment
    • Ultrasound
      • can be used to make diagnosis prenatally
  • Treatment
    • Nonoperative
      • observation and supportive treatment
        • indications
          • most patients
        • modalities
          • cauliflower ears frequently repsond to early treatment with compressive bandages
          • cervical kyphosis frequently resolves spontaneously
    • Operative
      • occipital-cervical fusion
        • indications
          • atlantoaxial instability with neurologic symptoms
            • risk of quadriplegia is a concern
      • posterior cervical fusion
        • indications
          • cervical kyphosis that does not resolve spontaneously
      • thoracolumbar fusion
        • indications
          • kyphoscoliosis of thoracolumbar spine
          • if progressive may require ASF / PSF
      • soft tissue surgical release
        • indications
          • early foot ankle deformity after initial period of casting
          • severe joint contractures (hip and knee)
      • osteotomies for correction
        • indications
          • progressive valgus deformity of lower extremities (with dislocated patellae)
          • resistant or recurrent clubfeet
          • distal femoral extension osteotomies for fixed knee flexion contractures
          • valgus intertrochanteric osteotomies +/- acetabuloplasty for early hip subluxation
      • total joint arthroplasty
        • indications
          • end stage osteoarthritis of hips

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Questions (4)

(OBQ12.8) A child with a defect in the DTDST gene would have which of the following classic phenotypes?

QID: 4368
1

Blue sclera and bowing deformities

7%

(330/4720)

2

Mental retardation and cardiac malformations

6%

(270/4720)

3

Cauliflower ears and hitchhiker's thumb

63%

(2989/4720)

4

Craniosynostosis and complex syndactyly

12%

(585/4720)

5

Rhizomelic dwarfism and frontal bossing

10%

(451/4720)

L 3 B

Select Answer to see Preferred Response

(OBQ09.49) What is the genetic cause of the dwarfism characterized by a hitchhikers thumb, cauliflower swelling of the ears, and severe clubfeet?

QID: 2862
1

FGFr-2

8%

(292/3652)

2

FGFr-3

11%

(399/3652)

3

Sulfate transport protein

69%

(2506/3652)

4

CBFA-1

8%

(280/3652)

5

Gs Alpha Protein

4%

(156/3652)

L 2 B

Select Answer to see Preferred Response

(OBQ05.29) Figure A is a photograph of a newborn's hand. Genetic testing reveals a mutation in the SLC26A2 gene on Chromosome 5q and both the parents were carriers. What condition does this child have?

QID: 66
FIGURES:
1

Achondroplasia

5%

(92/1780)

2

Osteogenesis imperfecta

1%

(10/1780)

3

Hypochondroplasia

7%

(128/1780)

4

Diastrophic dysplasia

82%

(1462/1780)

5

Ehlers-danlos syndrome

5%

(84/1780)

L 1 D

Select Answer to see Preferred Response

(OBQ04.104) A 3-year-old child with short-limbed dwarfism has the clinical features shown in Figures A & B. What is the pathoanatomy of this disease?

QID: 1209
FIGURES:
1

Sulfate transport protein gene mutation affecting cartilage matrix formation

71%

(829/1165)

2

Mutation in the gene CBFA-1 affecting osteocalcin formation

6%

(68/1165)

3

Defect in lysosomal-storage

5%

(56/1165)

4

Defect in lipid-storage

1%

(11/1165)

5

Mutation in gene FGFR-3 resulting in growth plate growth abnormality

17%

(195/1165)

L 2 B

Select Answer to see Preferred Response

Evidence (6)
VIDEOS & PODCASTS (2)
EXPERT COMMENTS (8)
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