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Cardiopharyngeal Syndromes

2. Cardiopharyngeal Syndromes (p63, GBX2)                     

The head and heart musculature derives from a common progenitor field, called the cardiopharyngeal field. Any disturbance during development of this field can course craniofacial and cardiac anomalies. Many human syndromes include both head and heart anomalies and are potential cardiopharyngeal syndromes.

Head and heart development in mouse mutants​

  • Project description: We analyze the anatomy of mouse mutants to identify soft and hard tissue malformations. Our aims are to describe in detail the malformation of the head and the heart, their development, and the implications from observed malformations for our understanding of developmental mechanisms. Specifically, we want to analyze if the observed abnormalities are correlated with malformations in the cardiopharyngeal field, a mesodermal field that gives rise to branchiomeric and cardiac musculature. This part is also important as it contributes to our understanding of congenital defects in humans which often comprise cardiac and craniofacial anomalies. 

  • 2018-present: Kristen N. McPike - graduate student (PhD in Anatomy), HUCM, Dept. Anat., year 2020

  • Collaborator on this project is Dr. Julia C. Boughner (p63 mutants)

    • University of Saskatchewan College of Medicine, Dept. Anatomy, Physiology & Pharmacology, 107 Wiggins Road, Saskatoon SK S7N 5E5 Canada​

  • Collaborator on this project is Dr. Samuel T. Waters (Dbx2 neo mutants)​

    • University of District of Columbia,, College of Arts and Sciences, Division of Sciences and Mathematics; 4200 Connecticut Avenue NW, Washington DC, 20008​

1.

DiGeorge Syndrome

  • Currently the only syndrome under investigation for cardiopharyngeal defects and underlying mechanisms linked to cardiopharyngeal mesoderm

  • = 22q11.2 deletion syndrome; CATCH-22

  • Microdeletion in long (q) arm of chromosome 22, leading to a hypoplasia or aplasia of 3rd and 4th pharyngeal pouch derivatives

  • Some abnormal development of 1st arch components are also seen (cleft palate, nasal clefts, mouth abnormalities)

  • Other characteristics: low-set notched external ears, thyroid hypoplasia, and cardiac anomalies

2.

Treacher Collins syndrome (= "Treacher Collins–Franceschetti syndrome“ & “Mandibulofacial dysostosis”)

  • Rare genetic disorder (dominant autosomal, Chr5) characterized by craniofacial deformities; 1/10,000 births

  • Characteristics include

    • Micrognathia (small jaws): hypoplasia of zygomatic bone, maxilla and mandible

    • Underdeveloped zygomatic bones: downward slanting eyes and drooping part of lateral lower eyelids

    • Malformed or absent external and inner ears: conductive hearing loss

3.

Pierre Robin Sequence (= Pierre Robin syndrome & Pierre Robin anomaly)

  • Hypoplasia of mandible > tongue is displaced upward > cleft palate; defects of eye & ear

  • Glossoptosis:

    • Downward displacement or retraction of tongue, often accompanied by airway obstruction

    • Tongue is normal, but because of small mandible, tongue is large for airway and therefore causes obstruction

4.

Hemifacial microsomia, 1st & 2nd Arch Syndrome

  • Affects development of lower half of face, ears, mouth and mandible

  • Can occur unilaterally or bilaterally

  • If severe it can lead to difficulties in breathing, obstructing the trachea and requiring a tracheotomy

  • 2nd most common facial birth defect after clefts, with an incidence of 1 in 3500 to 4500 births

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