Diastrophic dysplasia
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A neonate has short-limbed short stature with rhizomelic limb shortening, thumbs that stick out abducted from the hand ("hitchhiker thumbs"), and ears that quickly become swollen and develop a calcified, cauliflower appearance. Cleft palate is present. Within months, severe joint contractures and progressive scoliosis develop.
AR; SLC26A2 (DTDST, the diastrophic dysplasia sulfate transporter). The same gene causes a clinical spectrum:
- Achondrogenesis type 1B (ACG1B): perinatal lethal; complete loss of function
- Atelosteogenesis type 2: neonatal lethal; severe
- Diastrophic dysplasia (DTD): survivable; this leaf
- Recessive multiple epiphyseal dysplasia (rMED): mildest; adult-onset joint pain only
Phenotypic severity correlates with residual transporter function.
- Short-limb short stature: rhizomelic shortening; final adult height ~120 cm
- "Hitchhiker thumbs": abducted, proximally placed thumbs (pathognomonic)
- "Cauliflower ear": cystic swelling of the auricle in infancy progressing to fibrocalcific deformity (~80%)
- Cleft palate (~50%)
- Joint contractures: congenital and progressive; club foot common
- Severe progressive scoliosis: major management challenge
- Cervical kyphosis in infancy (airway risk)
- Normal cognition
- Hearing usually normal
- Clinical (short stature + hitchhiker thumb + cauliflower ear is highly characteristic)
- Skeletal survey: short tubular bones, vertebral anomalies, broad short metacarpals
- SLC26A2 sequencing for confirmation; carrier testing in family
- Prenatal: short long bones + short hands on US, sometimes cleft palate visible
- Achondroplasia (FGFR3): short stature with macrocephaly + frontal bossing, no hitchhiker thumb, no ear deformity
- Achondrogenesis type 1B: same gene, perinatal lethal
- Atelosteogenesis type 2: same gene, more severe than DTD
- Larsen syndrome: multiple joint dislocations + flat facies; no hitchhiker thumb
- Cervical spine MRI in infancy (kyphosis can compress cord; major life-threatening issue)
- Orthopedic: scoliosis surveillance and bracing/surgery; club foot correction; joint contracture management
- ENT: monitor for airway issues, treat ear deformity (often cosmetic only)
- Cleft palate repair
- Audiology baseline and monitoring
- Anesthesia: difficult airway anticipated; cervical instability precautions
- AR; ~25% recurrence; carrier testing of partners
"Diastrophic = Distorted thumbs, Distorted ears": hitchhiker thumb + cauliflower ear is the recognition combo. Then add short-limbed short stature + cleft palate + cervical kyphosis to anchor the syndrome.