Medical Care
Medical care
Medical care is supportive in achondrogenesis. No treatment is available for the underlying disorder.
Genetic counseling
Achondrogenesis type IA and type IB are inherited as autosomal recessive disorders. For a couple who has an affected child, the recurrence risk is 1 in 4 (25%). This risk is markedly higher than the recurrence risk for achondrogenesis type II, which is usually caused by a new dominant mutation.
In type II, asymptomatic carriers may be present in the families of affected patients. It is important to consider the possibility of germline mosaicism in de novo dominant conditions such as achondrogenesis II. Couples having delivered a pregnancy considered to have a de novo dominant disorder should be counseled that the recurrence risk is greater than the background risk, although the exact recurrence risk is uncertain. If 2 or more siblings are affected, the recurrence risk increases further. [18]
Genetic counseling must rely on accurate differentiation between achondrogenesis type I and type II.
Consultations
Consultations should be made with the following specialists:
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Clinical geneticists
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Radiologists
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Anatomical pathologists
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Obstetricians
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Neonatologists
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Ultrasonographers
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An infant with achondrogenesis type II. Note the disproportionately large head, large and prominent forehead, flat facial plane, flat nasal bridge, small nose with severely anteverted nostrils, micrognathia, extremely short neck, short and flared thorax, protuberant abdomen, and extremely short upper extremities.
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This posteroanterior (PA) view radiograph of an infant with achondrogenesis type II shows the relatively large calvaria with normal cranial ossification, short and flared thorax, bell-shaped cage and shorter ribs without fractures, relatively well ossified iliac bone with long crescent-shaped medial and inferior margins, and short tubular bones. The sacrum, pubis, and ischium are not visible.
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Lateral view radiograph of an infant with achondrogenesis type II. Note the relatively large head with a normal cranial ossification and enlarged fontanelles, short ribs, absent sternal ossification, ossification only in anterior parts of the vertebral bodies, and short and curved femora.
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An infant with achondrogenesis type II. Note the protuberant abdomen and extremely short lower extremities.
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Photomicrographs of the costal cartilage of an infant with achondrogenesis type II. This shows prominent hypercellularity, large chondrocytes, deficient matrix, and abnormally large, stellate cartilage canals. The left image is X42, and the right image is X106.
Tables
| IA | IB | II | |
|---|---|---|---|
| Skull | Absent or severely reduced ossification | Normal or reduced ossification for age | Normal ossification |
| Long bones | Short and bowed Stellate, longitudinally oriented Metaphyseal spurring |
Very short, square or stellate Metaphyseal spurring Poor ossification of phalanges |
Short and bowed Metaphyseal flaring and cupping |
| Thorax | Short, barrel-shaped Ribs: Short and horizontally oriented, with splayed anterior ends Multiple fractures (beaded appearance) |
Ribs: Short and thin, typically no fractures | Short, barrel- or bell-shaped Short ribs, no fractures |
| Spine | Vertebral bodies: Absent or rudimentary ossification |
Vertebral bodies: Absent or rudimentary central ossification Vertebral lateral pedicles: Usually ossified |
Variable Vertebral bodies and pedicles: Ossified or unossified |
| Pelvis | Sacrum: Absent or rudimentary ossification |
Iliac bone: Abnormal ossification giving a crescent-shaped appearance Ischium: Not ossified. |
Halberd-like iliac bone Ischial and pubic bones: Unossified |
