109 Turner Syndrome
Chromosome X monosomy
Short stature, primary amenorrhea, webbed neck, lymphedema of hands and feet at birth, shield chest, coarctation of the aorta, hypoplastic nails, short metacarpals, multiple pigmented nevi
Frequency: 1 in 5,000 female births.
Genetics
In 50% of patients is due to monosomy X (45,X), in 80% of cases only the maternal X is present; mono- somy X is highly lethal (99% of conceptions are spontaneously aborted); 25% of these patients are mosaics, 15% have isochromosome Xq, 7% X-ring, 2% X-short arm deletions; some of these karyotypes result in streak ovaries and small stature without associated dysmorphic features; critical region Xp11.2–22.1.
Clinical Features
• Short stature (final height usually between 122 and 152 cm)
• Triangular face, hypertelorism, ptosis, epicanthal folds
• Depressed mouth corners, high-arched palate (35%), micrognathia, premature eruption of teeth
• Low-set, prominent ears
• Strabismus (20%)
• Low posterior hairline, short/webbed neck, ptery- gium colli, posterior cervical hygroma
• Shield chest, widely spaced nipples
• Left-sided cardiac anomalies (coarctation of aorta, bicuspid aortic valve, aortic valve disease), hypertension
• Cubitus valgus, brachydactyly, clinodactyly
• Congenital lymphedema of hands and feet, redun- dant skin on neck, nail hypoplasia, multiple pig- mented nevi, seborrhea, hirsutism, keloid forma-
• Renal malformations (horseshoe kidneys, ureteraltion duplication, renal ectopia, obstructive uropathy)
• Gonadal dysgenesis or streak gonads, resulting in primary amenorrhea and infertility, failure of sec- ondary sexual development
• Frequent association with autoimmune diseases (diabetes mellitus, hypothyroidism, inflammatory bowel disease)
• Presence of Y chromosome sequences predisposes to gonadoblastoma (15–25%)
• Visuo-spatial deficit, deficit in perceptual organi- zation and fine motor skills, learning disabilities, hyperactivity
Differential Diagnosis
• Noonan syndrome
• Gonadal dysgenesis XX and XY types
• Multiple pterygium syndrome
• Klippel-Feil anomaly
Radiographic Features Extremities
• Cubitus valgus (70%)
• Madelung-like deformity
• Depression of the medial tibial condyle, “mush- room” projection (exostosis-like) of the medial aspect of proximal tibia (60%), irregularity of the tibial metaphysis and epiphysis
• Lateral dislocation of patella, hypoplastic patella
• Tibiotalar slant Hands and Feet
• Short 4th metacarpals/metatarsals (60%)
• Carpal/tarsal fusions
• Radiocarpal angulation, small carpal angle
• Drumstick distal phalanges
• Short middle phalanx of 5th finger
• Disproportionately long 4th finger phalanges
• Coarse reticular pattern of carpal bones
• Small carpal bone area
• Pes cavus Skull
• Brachycephaly with short cranial base
• Parietal thinning
• Large sella, thinning of the posterior clinoids and dorsum sellae and double floor
• Extensive calcification of petroclinoid ligaments
• Excessive pneumatization of sphenoid sinuses
• Underdeveloped mastoids
• Small facial bones,narrow maxilla and palate (80%)
• Short mandible (70%) Spine
• Scheuermann-like changes
• Scoliosis, kyphosis
• Hypoplasia of cervical vertebrae
• Vertebral fusions
• Spina bifida Chest
• Premature sternal fusion, mild pectus excavatum
• Cervical ribs (100%)
• Thin lateral clavicles and posterior ribs
Generalized Skeletal Abnormalities
• Osteoporosis, course trabecular pattern (50%)
• Normal skeletal maturation until puberty, then bone age delay
Pelvis
• Male configuration of the pelvic inlet
• Protrusio acetabuli
• Hip dislocation
Turner Syndrome 923
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a
c
b
Fig. 109.1 a–c. Patient 1, 15 years. Note a trian- gular face, hypertelorism, ptosis, down-slanting palpebral fissures, and low-set ears; b micro- gnathi and pterygium colli; c low posterior hair- line
Fig. 109.2 a, b. Patient 2, newborn. Microcephaly, parietal thinning, maxillary hypoplasia, mild micrognathia, and increased angle of the skull base
a b
Fig. 109.3. Patient 2, newborn.
Note bilateral proximal radial hy- poplasia with radial head luxation, and thin clavicles and ribs
Bibliography
Ferguson-Smith MA. Karyotype-phenotype correlations in gonadal dysgenesis and their bearing on the pathogenesis of malformations. J Med Genet 1965; 2: 142–55
Morrison SC. Punctate epiphyses associated with Turner syn- drome. Pediatr Radiol 1999; 29: 478–80
Ogata T, Matsuo N. Turner syndrome and female sex chromo- some aberrations: deduction of the principal factors in- volved in the development of clinical features. Hum Genet 1995; 95: 607–29
Pamer CG, Reinchmann A. Chromosomal and clinical findings in 110 females with Turner syndrome. Hum Genet 1976; 35:
35–43
Rosenfeld RG, Frane J, Attie KM, Brasel JA, Burstein S, Cara JF, Chernausek S, Gotlin RW, Kuntze J, Lippe BM et al. Six-year results of a randomized, prospective trial of human growth hormone and oxandrolone in Turner syndrome. J Pediatr 1992; 121: 49–55
Simpson LJ. Gonadal dysgenesis and abnormalities of the hu- man sex chromosome: current status of phenotypic-kary- otypic correlations. Birth Defects Orig Art Ser 1975; 11:
23–59
Zinn AR, Tonk VS, Chen Z, Flejter WL, Gardner HA, Guerra R, Kushner H, Schwartz S, Sybert VP, van Dyke DL, Ross JL.
Evidence for a Turner syndrome locus or loci at Xp11.2- p22.1. Am J Hum Genet 1998; 63: 1757–66
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Fig. 109.4. Patient 3, age 13 years. Note vertebral end-plate irregularities reminiscent of Scheuermann disease. Also note spondylolysis and spondylolisthesis at L5–S1
Fig. 109.5. Patient 4, adolescent.
Narrowing of basilar portions of iliac bones, and mild protrusio ac- etabuli
Fig. 109.6. a Patient 2, newborn; b patient 5, age 11 years;
cpatient 6, adolescent. a Inward bulging of medial aspect of the proximal tibial metaphysis and retarded ossification of dis- tal femoral and proximal tibial epiphyses. b, c Note medial tib-
ial exostosis-like projections, depression of medial portion of tibial plateau, and coarse reticular bone pattern, most promi- nent at the metaphyses and epiphyses. In b note also mild tibiotalar slant
a c
Fig. 109.7. Patient 7, adult. Made- lung-like forearm deformity, with dorsolateral bowing of radius, ulnar deviation of distal radial epiphysis, and triangularization of carpus, with the lunate at the apex
b
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Fig. 109.8. a Patient 2, newborn; b patient 5, age 11 years;
cpatient 3, age 13 years; d patient 8, age 14 years. a Note short- ening of 4th metacarpal and 5th distal phalanx. b, c Shortening of 4th metacarpal, coarse trabecular pattern about carpal
bones and metacarpal epiphyses, and drumstick distal pha- langes are apparent. d Round expansion of a distal phalanx is shown, resembling a drumstick
a
b
d c
Fig. 109.9. aPatient 2, newborn. Note soft tissue swelling due to lymphedema of the feet. b Patient 7, adult. Note striking short- ening of the 4th metatarsal and reticulation of the cancellous bone
a b
