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Genetic counseling: 22q11 Deletion Syndrome

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22q11 Deletion Syndrome (a.k.a. Velocardiofacial Syndrome (VCF), DiGeorge Syndrome)

DiagnosisEdit

  • Caused by a deletion of material from one copy of the long arm of

chromosome 22

    • Submicroscopic deletion in DiGeorge Chromosomal Region

(DGCR)

    • Chromosome banding may sometimes detect deletion
    • FISH testing detects deletion in 95% of affected individuals
  • Autosomal dominant inheritance
    • About 94% of patients have de novo mutation
    • Parents of affected individuals should have FISH testing
      • Offspring of affected individual have 50% chance of inheriting 22q11 deletion
      • Recurrence risk for siblings of affected individual is very small if FISH testing shows the parents do not have the deletion
  • Several genes are located within the DGCR
    • Some of these gene products have been identified
    • Cannot predict genotype-phenotype correlation because size of

deletion does not seem to correlate with severity of characteristics Characteristic Findings:

  • Congenital heart disease
    • Found in about 74% of affected individuals
    • Usually conotruncal malformations
      • Teratology of Fallot
      • Interrupted aortic arch
      • Truncus arteriosis
      • Ventricular septal defect (VSD)
    • Conotruncal malformations identified in infancy/early childhood

and can be surgically repaired

    • Mild problems with the aorta may not be recognized
  • Palatal abnormalitites
    • Found in about 69% of affected individuals
    • Several types of abnormalities observed
      • Velopharyngeal incompetance (VPI)
      • Submucosal cleft palate
      • Visible cleft palate
      • Cleft lip and palate
      • Bifid uvulae
    • May be surgically repaired
    • May affect speech development
    • Speech therapy is recommended
  • Feeding difficulties
    • Found in about 30% of affected individuals
    • May be due to palate or heart problems
    • May also be caused by problems transporting food from the

mouth to the esophagus

    • Signs of feeding difficulty
      • Infants are irritable, gag, vomit, have a weak suck
      • Younger children find spoon feeding easier but have trouble drinking from a cup
      • Older children have difficulty with lumpy, crunchy foods
    • May be treated by teaching children better feeding practices
  • Immunodeficiency
    • Caused by small or missing thymus gland
    • Causes greatest number of problems in first year of life
    • Children may have frequent infections such as bronchitis or

pneumonia

    • As children grow older, T cell production improves
  • Hypoparathyroidism
    • Regulates calcium levels in bloodstream
      • Absence or underdevelopment leads to hypocalcemia
      • May cause tremors, seizures, muscle spasms, abnormal breathing, and abnormal heart rhythms
    • Diagnosed by a blood test
    • Treated with calcium supplements
  • Growth hormone deficiency
    • Approximately 41% of affected individuals are below the 5th

percentile in height

    • May be caused by abnormalities in formation of pituitary gland
      • In only about 1/10 of individuals with 22q11 deletion
      • Causes reduced levels of growth factors
    • Can be determined with a blood test
    • Treatment with injections of growth hormones
  • Characteristic Facial Features
    • Nose - bulbous nasal tip, prominent nasal root, nasal dimple
    • Ear - overfolded helices; cupped, microtic, and protuberant ears;

narrow external auditory meati

    • Eyes - hooding of upper or lower lid, ptosis, epicanthal folds
  • Renal anomalies
    • Found in about 37% of affected individuals
    • Includes single kidney, echogenic kidney, small kidneys, and other

renal anomalies

  • Juvenile rheumatiod arthiritis (JRA)
    • About 150 times more frequent than in general population
    • Age of onset is 17 months to 5 years
  • Developmental difficulties
    • Found in 70-90% of affected individuals
    • Development of motor skills
      • Due to problems with muscle strength and coordination
      • Often delayed in sitting, crawling, walking
      • May be helped by physical therapy
  • Learning
    • Typically have slower learning rate
    • Follow same learning sequence as other children but at slower pace
    • Often have strong verbal skills but weaker math skills
    • May have difficulty paying attention
    • Early diagnosis and intervention important
    • May require learning support
  • Speech and language
    • Verbal speech usually does not develop until 2-3 years
    • May also have difficulty in formation of sounds
    • Palatal problems often lead speech problems
    • Early intervention by speech and language pathologist is important
  • Behavioral difficulties
    • About 40% of affected individuals develop psychiatric illness
      • Depression
      • Anxiety
      • Schizophrenia
      • Bipolar disorders
    • May be evident as tantrums and mood swings in childhood
    • Social skills training and counseling may be necessary


ResourcesEdit

  • Cincinnati Velocardiofacial Support Group
Teresa Paul
9327 Bluewing Terrace
Cincinnati, Ohio 45236
Email: MOTHERTP@aol.com
  • Velo-Cardio-Facial Syndrome Education Foundation
Jacobson hall Room 707
University Hospital
750 East AdamsStreet
Syracuse, NY 13210
Phone: 315-464-6590
Email: vcfsef@hscsyr.edu
Web: [1]
  • International DiGeorge/VCF Support Network
c/o Family Vioces of New York
461/2 Clinton Avenue
Cortland, NY 13045
Phone: 607-753-1621 (day) 607-753-1250 (evening)
  • Chromosome Deletion Outreach, Inc.
PO Box 724
Boca Raton, FL 33429-0724
Phone: 561-395-4252
Email: cdo@worldnet.att.net
Web: [2]

ReferencesEdit

  • The Children's Hospital of Philadelphia. Faces of Sunshine: The 22q11.2 Deletion.
  • NIH Gene Clinics web site: [3]
  • OMIM: [4]
  • Smith's. Shprintzen Syndrome.

NotesEdit

The information in this outline was last updated in 2002.


Material obtained under GFDL Licence from http://en.wikibooks.org/wiki/Handbook_of_Genetic_Counseling

Heckert GNU white Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License."

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