18. Achondroplasia Flashcards Preview

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Flashcards in 18. Achondroplasia Deck (20)
1

problem

failure of longitudinal bone growth ( endohondral ossification ) --> short limbs

2

appearance

Short extremities with normal sizes head and chest ( large head RELATIVE to limbs )

3

Achondroplasia --> membranous ossification

not affected ( normal head and chest )

4

Achondroplasia --> pathophysiology

constitutive activation of FGFR3 --> inhibits chondrocyte proliferation --> impaired cartilage proligeration in growth plate --> impaired endochondtral ossification

5

mutation in achondriplasia

FGFR3 ( activation )

6

Achondroplasia --> sporadic vs inherited mutation

>85% sporadic

7

Achondroplasia --> inherited type - mode of inheritance

AD ( if homozygosity --> lethal )

8

homozygotic achondroplasia

lethal

9

Achondroplasia is the MCC of

dwarfism

10

Dwarfism is

a condition of short stature

11

MCC of Dwardism

achondroplasia

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achondroplasia - mental function

normal

13

life span

normal

14

fertility

normal

15

achondroplasia - sporadic mutation frequency is increased with

paternal age

16

• Achondroplasia is an autosomal ____ (dominant/recessive) trait. The majority (85%) of cases are ____ (inherited/sporadic).

Dominant; sporadic

17

• You see a 4-year-old boy with achondroplasia and note he has short limbs. Why is this seen in patients with achondroplasia?

The underlying problem in patients with achondroplasia is failure of long bone growth (endochondral ossification)

18

• You see a 4-year-old boy with achondroplasia and note that he has short limbs, but an appropriate head circumference. How is this possible?

Patients with achondroplasia have defects in endochondral, not membranous, ossification—the skull and axial bones are unaffected

19

• What is the result of a fibroblast growth factor receptor 3 (FGFR3) mutation in patients with achondroplasia?

The gene is active, inhibiting chondrocyte proliferation & cannot form cartilaginous model for endochondral ossification of long bones

20

• You meet a boy with a large head and short limbs whose PTH levels are normal. What protein is consistently activated?

Fibroblast growth factor receptor (FGFR3) (this boy has achondroplasia, the most common cause of dwarfism)

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