2 Achondrogenesis, Type IB A

Achondrogenesis,Type IB 579

2 Achondrogenesis,Type IB A

Fraccaro type Extremities • Extremely short tubular bones, with squared, Severely shortened long bones with loss of longitudi- trapezoid, or stellate appearance nal orientation; unossified fibulas; deficient ossifica- • Wide and cupped ends of the long bones, with lat- tion of vertebral bodies, pelvis, and sacrum eral spurs • Unossified fibulas Frequency: 1 in 50,000 births. Skull • Ossified or only mildly underossified calvarium Genetics Autosomal recessive (OMIM 600972), caused by mutations in the DTDST gene at 5q32-q33 Bibliography

Clinical Features Beluffi G. Achondrogenesis, type I. Rofo Fortschr Geb Rönt- • Fetal hydrops, polyhydramnios genstr Nuklearmed 1977; 127: 341–4 • Borochowitz Z, Lachman R, Adominan GE, Spear G, Jones K, Premature birth, stillbirth or death within min- Rimoin DL. Achondrogenesis type I: delineation of further utes in large proportion of cases heterogeneity and identification of two distinct subgroups. • Marked micromelic dwarfism J Pediatr 1988; 112: 23–31 • Normocephaly, but head appearing large because Jaeger HJ, Schmitz-Stolbrink A, Hulde J, Novak M, Roggen- of small body kamp K, Mathias K. The boneless neonate: a severe form of • achondrogenesis type I. Pediatr Radiol 1994; 24: 319–21 Severe midface hypoplasia Maroteaux P, Lamy M: Le diagnostic des nanismes chrondro- • Low nasal bridge dystrophiques chez les nouveau-nés. Arch Fr Pediatr 1968; • Micrognathia 25: 241–62 • Short neck Spranger JW, Langer LO, Wiedemann HR. Bone dysplasias. An • Short trunk, barrel-shaped chest atlas of constitutional disorders of skeletal development. • W.B. Saunders Company, Philadelphia, 1974, pp. 24–5 Overdistended abdomen Superti-Furga A, Hastbacka J, Wilcox WR, Cohn DH, van der • Edema of soft tissues Harten HJ, Rossi A, Blau N, Rimoin DL, Steinmann B, Lan- • Prenatal detection of micromelia by ultrasound der ES, Gitzelmann R. Achondrogenesis type IB is caused by mutations in the diastrophic dysplasia sulphate trans- Differential Diagnosis porter gene. Nat Genet 1996; 12: 100–2 • Tretter AE, Saunders RC, Meyers CM, Dungan JS, Grumbach K, Achondrogenesis, types IA (Houston-Harris) and Sun CC, Campbell AB, Wulfsberg EA. Antenatal diagnosis II of lethal skeletal dysplasias. Am J Med Genet 1998; 75: • Hypochondrogenesis 518–22 Van der Harten HJ, Brons JT, Dijkstra PF, Niermeyer MF, Mei- Radiographic Features jer CJ, van Giejn HP,Arts NF. Achondrogenesis-hypochondrogenesis: the spectrum of chondrogenesis imperfecta. A Spine radiological, ultrasonographic, and histopathologic study • Absent/deficient ossification of vertebral bodies of 23 cases. Pediatr Pathol 1988; 8: 571–97 Pelvis Withley CB, Gorlin RJ: Achondrogenesis: nosology with • Small iliac wings evidence of genetic heterogeneity. Radiology 1983; 148: • Small pelvis with flattened acetabula 693–98 • Arched lower iliac margins • Absent/deficient ossification of pubis, ischium, and sacrum Chest • Barrel-shaped thorax • Short, thin, horizontal ribs with widened ends • Unossified sternum 580 Achondrogenesis,Type IB / Achondrogenesis,Type II

Fig. 2.1 a,b. Patient 1, stillborn. The skull is ossified. The thorax is barrel shaped. The ribs are short, horizontally oriented, and thin, with splayed ends. There are nor rib fractures. The vertebrae are ossified poorly or not at all. The iliac wings are short, with arched lower iliac margins, and the pubis, ischium, and sacrum are not ossified. The tubular bones in the limbs are extremely short and wide, squared off or trapezoid in appearance, with concave ends and lateral spurs. The fibulas are unossified. The abdomen is enlarged. (Reprinted, with permission, from Beluffi 1977)

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Fig. 3.1. Patient 1, stillborn at 32 weeks’ gestation. The calvarium is enlarged, with diminished, yet still appreciable, ossification. The thorax is barrel-shaped, with thin and horizontal ribs. There is no evidence of rib fractures. The scapulae are small and irregular, but the clavicles are normal. The vertebral bodies are severely underossified. The lumbar vertebrae, sacrum, ischia, and pubic bones are totally unossified. The shape of the ilia, with a concave medial and inferior border, is characteristic of this condition. The tubular bones in the limbs are very short and bowed, with cupped ends, but are less severely affected than in achondrogenesis type I. The abdomen and soft tissue are prominent