Prenatal Craniofacial Development - 10

Birth Defects Involving the Pharyngeal Apparatus
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 : a group of abnormalities occurring together

22q11 (.2) Deletion Syndrome is also called   (broad definition)

22q11 (.2) Deletion Syndrome is caused by  

22q11 (.2) Deletion Syndrome occurs   live births

What is the most common microdeletion syndrome?

22q11 (.2) Deletion Syndrome includes   and  .

22q11 (.2) Deletion Syndrome is characterized by   of the pharyngeal apparatus

  is a key etiologic gene

TBX1 (T-box 1) encodes a  

TBX1 (T-box 1) is expressed in the   - Ectoderm, endoderm and mesoderm (regulates neural crest-derived cells indirectly via intercellular signaling)

22q11 (.2) Deletion Syndrome Craniofacial phenotypes

• Small  (micrognathia), small  , square  
• Low-set  , abnormally folded  ,   abnormality
•   defects (submucous or overt cleft, high arched palate, bifid uvula)
• Mostly explained by impaired development of the structures derived from the  

22q11 (.2) Deletion Syndrome Cardiovascular phenotypes

• Abnormal   – Interrupted  , Aberrent  

22q11 (.2) Deletion Syndrome Cardiovascular phenotypes

• Heart Defects –  ,  

22q11 (.2) Deletion Syndrome deficiency in the pharyngeal glands

•   (low serum calcium levels. Might cause seizures)
- Lack of   due to impaired/failed development of
the  
•   (recurrent ear and respiratory infections)
- Lack of, or impaired function of,   due to impaired development
of the  

22q11 (.2) Deletion Syndrome deficiency in the pharyngeal glands is caused by developmental defects in the  

Treacher Collins Syndrome is also called  

Treacher Collins Syndrome occurs   births

Treacher Collins Syndrome is categorized as disorder of   (mostly  )

Treacher Collins Syndrome characteristics include

•  ,  ,   and  
•  ,  
•   and other deformity of the  ,  

Treacher Collins Syndrome is caused by   mutation in  , encoding a protein ‘ '

Treacle is involved in making  

TCOF1 is expressed in the   and  

TCOF1 haplo-insufficiency leads to   due to increased cell death and decreased cell proliferation

 : one cause leading to a chain of developmental malformation

(Pierre) Robin Sequence (Syndrome) occurs in   births

(Pierre) Robin Sequence (Syndrome) is characterized as disorder of   (mostly  )

(Pierre) Robin Sequence (Syndrome) characteristics include

•   (small lower jaw),   (downward displacement or retraction of the tongue),  
•   obstruction ->  distress.   difficulties
• Many   implicated, including  

  Syndrome = Oculoauriculovertebral spectrum, Hemifacial microsomia

Goldenhar Syndrome occurs in   births

  characteristics include

• Under-development of the   ( ),  ,  ,   and   usually on   side
• Abnormal development of the   pharyngeal arches
• May be accompanied by defects in other organs (heart, kidney, lung, brain, vertebrae …)
• Multifactorial etiology – chromosomal anomalies, gene mutations, twin pregnancy, maternal diabetes

Branchial Fistulas and Lateral Cervical Cyst is the aberrant development of the  

Normally, 2nd, 3rd, 4th pharyngeal clefts are covered up by the 2nd pharyngeal arch, become  , and then  

Thyroglossal Cyst and Fistula

• During migration of the thyroid gland from the foramen cecum, a   forms connecting the two ( )
• Thyroglossal duct normally  . If not, --> 
• Thyroglossal cysts can  , creating a   connecting to outside

Thyroglossal Cyst and Fistula can lead to  ,  ,  

Thyroglossal cysts may lie at any point along the   of the  

Thyroglossal Cyst and Fistula are always close to the  

Tongue Tie (Ankyloglossia) affects  ,  

The condition in which the tongue is not freed from the floor of the mouth due to the frenulum at the tip of the tongue is called