Clinical Correlations (Exam 1)

Question 1

Causes of congenital anomalies:

Answer 1

Genetic Mechanisms (25%)
Environmental (Teratogens) (10%)
Multi-factorial Mechanisms (25%)

Question 2

Failure in normal developmental events may lead to what outcomes:

Answer 2

1. Failure of cells/tissues to migrate
2. Failure reciprocal signaling between tissues -> Failure of induction of tissues or cells
3. Failure of cell survival-> triggers apoptosis
4. Failure to proliferate
5. Failure to fusion (ex. cleft palate)
6. Failure to differentiate: Didn’t form a structure

Question 3

what percentage of anomalies are craniofacial defects?

Answer 3

33%

Question 4

What is Holoprosencephaly?

Answer 4

Failure of forebrain to differentiate leading to midline facial clefts

Question 5

What is Treacher Collins Syndrome?

Answer 5

• Cause: Genetic mutation
• Gene function: Impacts NC cell survival and formation of ecomesenchyme. Outcome is decreased proliferation of ectomesenchyme 1st arch region.
• Outcome: Ecomesenchyme derived structures affected
• Characteristic features include:
• Hypoplasia of the zygomatic bone and maxilla
• Hypolasia of mandible- Micrognathic (small jaw)
• Cleft of the secondary palate
• Overcrowding of the teeth
• Downslanting eyes
• Malformation of the pinnae and external auditory meatus– Deafness
• Normal sized nose but appear relatively large

Question 6

What is DiGeorge and Velo-Cardio-facial syndrome?

Answer 6

Putative outcome:

• Mutation prevents signaling between pouch endoderm (epithelium and ectomesenchyme/NC associated with each pouch
• Prevents normal differentiation of CT ectomesenchyme and pouch epithelial derivates
• Abnormalities often associated wit differentiation of third and 4th arch/pouch

Characteristic feature include:

• Cardiac defects
• Abnormal facial development
• Thymic hypoplasia or aplasia
• Cleft Papate
• Hypoparathyoidism

Question 7

Abnormalities with development and obliteration of pharyngeal clefts:

Answer 7

• Defects in formation of 1st cleft can lead to preauricular ( in front of ear) cysts or fistulas

Question 8

Pharyngeal (Branchial) cleft cysts/fistulas occur due to:

Answer 8

Failure of 2nd PA to overgrow and the 3rd and 4th arch and obliterate cervical sinus

Question 9

Bifid tongue is caused by:

Answer 9

Failure of lateral lingual swellings to fuse in midline results in a midline lingual cleft. Considered a minor anomaly with rare occurrence

Question 10

Ankyloglossia:

Answer 10

May result when there is a failure of the ventral surface of the tongue to become free anteriorly from the floor of the mots. A short thick lingual frenulum with anterior attachment limits mobility of tongue. Minor abnormality

Question 11

Persistent Thyroglossal duct:

Answer 11

Filure of thyroglossal duct to degenerate leads to cyst formation in the midline of the neck. Position of cyst may vary. The cyst may contain remnant thyroid follicular cells

Question 12

Lingual thyroid tissue:

Answer 12

Ectopic thyroid tissue may occur if fragments of thyroid gland become detached during migration or if the gland fails to migrate from its site of origin

Question 13

Laryngomalacia: (Soft larynx)

Answer 13

• Most common congenital anomaly of the larynx
• Characterized by partial or complete collapse of the epiglottis and/or arytenoid cartilages

Outcome: most commonly results in a characteristic high-pitched squeaking noise on inhalation. ( Inspiratory stridor-high pitched sound)

• the epiglottis is small and curled on itself. Approximation of the posterior edges of the epiglottis contributes to the inspiratory obstruction