Genetics of Skeletal Dysplasias (t1.2)

Question 1

Achondroplasia

Answer 1

FGFR-3 (fibroblast growth factor receptro):Inhibit chondrocyte proliferation

Short stature (skeletal dysplasia) Norma to large head rhizomelic shortening of limbs Short arms and legs (hum/fem shortest) normal sized trunk ch

Question 2

Thanatophoric dysplasia

Answer 2

FGFR-3 (fibroblast growth factor receptro):Inhibit chondrocyte proliferation

Severe dwarfism marked limb shortening small chest large head Lethal after birth due to respiratory compromise

Question 3

Hypochondroplasia

Answer 3

FGFR-3 (fibroblast growth factor receptro):Inhibit chondrocyte proliferation

Milder dwarfism than achondroplasia

Question 4

Multiple Epiphyseal Dysplasia

Answer 4

COMP (cartilage oligometric matrix protein) or type XI collagen: abnormality of cartilage formation

Short stature (skeletal dysplasia) Early onset osteoarthritis

Question 5

Multiple Epiphyseal Dysplasia

Answer 5

COMP (cartilage oligometric matrix protein) or type XI collagen: abnormality of cartilage formation

Short stature (skeletal dysplasia) Early onset osteoarthritis

Question 6

Spondyloepiphyseal Dysplasia

Answer 6

Type II collagen: Defect in cartilage matrix formation

Short stature (skeletal dysplasia), short trunk spine malformation, coxa vara, myopia, retinal degeneration

Question 7

Diatrophic dysplasia

Answer 7

Sulfate transporter: defect in sulfation of proteoglycan

Fraccato-type achondroplasia dwarfism fetal hydrops

Question 8

Schmid Metaphyseal Chondrodysplasia

Answer 8

Type X collagen: defect in cartilage matrix formation

Short sature, coxa vara, genu varum, involvement in metaphyses of long bones but not spine Less severe than in Jansen type-No disorganized metaphyseal calcification

Question 9

Jansen Metaphyseal Chondrodysplasia

Answer 9

PTH/PTHrP receptor (parathyroid hormone, parathyroid hormone-related protein): Functional defect of parathyroid hormone

Short limbs, facies, skeletal malformations Sclerotic bones in back and cranial bones-may lead to blindness or deafness Hypercalcemia

Question 10

Cleidocranial Dysplasia

Answer 10

Runx2 (cbfa-1): impaired intramembranous ossification

Hypoplasia or aplasia of clavicles, open skull suture, mild facial hypoplasia, wide symphysis pubis, mild short stature, dental abnormalities, vertebral abnormality