achondrogenesis type 2
The Langer Saldino syndrome or achondrogenesis type II is a subtype of achondrogenesis. It is an extremely rare fatal skeletal dysplasia.
Pathology
Genetics
Majority of cases are sporadic. Autosomal dominant inheritance is also another mode. There is mutation in the collagen type II gene (COL2A1) on chromosome 12q which is responsible for type II collagen encoding.
Clinical presentation
Majority of cases are stillborn or die within few hours after birth. The neonate is extremely short stature and present with large calvarium, large fontanelles, hypertelorism, depressed nasal bridge, anteverted nostrils, hypertrophied tongue and micrognathia.
Other abnormalities include a short neck, short limbs (rhizomelic), narrow thorax and distended abdomen.
Occasionally other abnormalities such as microtia, cleft palate, polydactyly, hydrops and cystic hygroma can be present.
Radiographic features
Radiographic features include
- normal cranial ossification
- short ribs without fracture
- short and broad tubular bones with metaphyseal widening and spurs
- disproportionately long fibula
- squaring of iliac wings with a horizontal acetabular angle.
- insufficiently ossified vertebrae, ischium, pubic bone, calcaneum and talus.
Prenatal ultrasound
Prenatal ultrasound makes it possible for early detection of various skeletal dysplasias: as early as 15 to 19 weeks of gestation. Findings may include:
- polyhydramnios
- nuchal edema
- hydrops
- cystic hygroma
- short limbs
- cleft palate
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