pharyngeal arches and clinical correlation

Question 1

first arch syndrome

Answer 1

• abnormal development of the firs arch

- results from insufficient migration of neural crest cells

Question 2

3 manifestations of first arch syndrome

Answer 2

• treacher collins syndrome
• robin sequence
• hemifacial microsoma

Question 3

hemifacial microsoma

Answer 3

• small and flat bones
• vertebral defects
• cardiac defromities
• unknown cure

Question 4

treacher collins syndrome

Answer 4

• malar hypoplasia
• mandibular hypoplasia
• eye and ear malformations
• autosomal dominant but has been replicated in lab with teratogens

Question 5

robin syndrome

Answer 5

• alters first arch structures-mandible is most severely affected
• may have genetic/ environmental bias
• may also result from deficiencies of amniotic fluid

Question 6

digeorge syndrome (primary cause)

Answer 6

failure of the 3rd and 4th pharyngeal pouch to differentiate and due to poor neural crest cell migration

Question 7

digeorge syndrome (prognosis)

Answer 7

• born without (or hypoplasia of) thymus (neural crest contributes to connective tissue of the thymus)
• absence of parathyroid glands
• cardiovascular defects
• facial anomalies including cleft palate

Question 8

difeorge syndrome is due to

Answer 8

• a small deletion in chromosome 22

- teratogens during 3week of development