Skeletal dysplasia Flashcards
Most common form of short-limbed dwarfism
Achondroplasia
Inheritance of achondroplasia?
Autosomal dominant, 80% new mutations
Most consistent sonographic finding in achondroplasia?
Short long bones, esp femur, btw 21-27w (<3rd percentile) - but important finding is initially normal 1st & 2nd trimester measurements
Other sonographic features of achondroplasia
Normal shape of femur Macrocrania Frontal bossing Protuberant abdomen Trident-shaped hand Polyhydramnios
What is diastropic dysplasia?
A recessively inherited form of short-limbed dwarfism, with the additional findings of thickening of the external ear and the characteristic “hitch-hiker” thumbs.
What is achondrogenesis?
A lethal, recessively inherited condition, there is deficient ossification of the vertebral bodies. As compared with achondroplasia, a greater discrepancy between head size and trunk exists in achondrogenesis.
What is Ellis-van Creveld syndrome?
Chondroectodermal dysplasia
Progressive distal shortening of the extremities and postaxial polydactyly are present
Congenital heart malformations are present in 50% of cases.
What is hypochrondroplasia?
The major findings are short stature and an increased upper-to-lower body segment ratio. The facial features are within normal limits.
What is the gene mutation in achondroplasia?
FGFR3
What is the most common lethal skeletal dysplasia?
Thanatophoric dysplasia
What are the classic features of thanatophoric dysplasia?
Cloverleaf skull in Type II Micromelic limbs Short ribs Narrow thorax Relative macrocephaly Frontal bossing Mid-face hypoplasia, Reduced height of the vertebral bodies Central nervous system abnormalities
Definition of micromelia
Shortening of the extremities involving the entire limb
Definition of rhizomelia
Shortening of the extremities involving the proximal segment
Definition of mesomelia
Shortening of the extremities involving the intermediate segment
Definition of acromelia
Shortening of the extremities involving the distal segment
Characteristics of osteogenesis imperfecta
Blue sclerae hearing abnormalities defective dentition hyperlaxity of the joints normal intelligence
Types and severity of OI?
Type I is the common mild form, type II is the perinatal lethal form, type III is the severe form, and type IV is the moderately clinically severe form.
More recently, an additional three types (V, VI, and VII) have been described.
The clinical severity of OI is type II> type III> types IV = V = VI = VII > type I.
What is campomelic dysplasia?
Symmetric bowing of the long bones of the lower extremities - acute femoral angulation, which typically occurs at the junction of the upper third and lower third of both femora, with resulting symmetrical shortening
Phenotypic sex reversal in some chromosomally male infants
Associated abnormalities including cleft palate, flat facies, micrognathia, hydrocephalus, and renal abnormalities.
What is short-rib polydactyly syndrome?
A group of rare, generally lethal skeletal dysplasias
Short horizontal ribs and long tubular bone changes that result in severe micromelia.
