2011 Group Project 2

From Embryology
Note - This page is an undergraduate science embryology student group project 2011.
2011 Projects: Turner Syndrome | DiGeorge Syndrome | Klinefelter's Syndrome | Huntington's Disease | Fragile X Syndrome | Tetralogy of Fallot | Angelman Syndrome | Friedreich's Ataxia | Williams-Beuren Syndrome | Duchenne Muscular Dystrolphy | Cleft Palate and Lip


A congenital disorder is one which is present at birth. They are often abnormalities that arise from errors that occur during development of the fetus. Some congenital abnormalities are genetic, and often run in families while others are spontaneous and have no genetic linkages. DiGeorge syndrome is a congenital abnormality that is caused by the deletion of a part of chromosome 22. The symptoms and severity of the condition is thought to be dependent upon what part of and how much of the chromosome is absent. [1].

About 1/4000 children born are affected by DiGeorge syndrome, with 90% of these cases involving a deletion of a section of chromosome 22 [2]. DiGeorge is quite often a spontaneous mutation, but it may be passed on in an autosomal dominant fashion. Some families have many members affected.

DiGeorge is a complex syndrome and patient cases vary greatly. The common symptoms present across numerous patients include

  • Abnormal faces
  • Congenital heart defects
  • Hypoparathyroidism with hypocalcemia
  • Cognitive, behavioral, and psychiatric problems
  • Increased susceptibility to infections
  • Hypoplasia or absence of the thyroid and parathyroid glands [3]

DiGeorge is a serious syndrome affecting many of the body systems. The clinical manifestations of the chromosome 22 deletion are significant and can lead to poor quality and a shortened lifespan for the patient. As there is currently no treatment education is vital to the wellbeing of those affected, directly or indirectly by this condition. [4] Current and future research is aimed at how to prevent and treat the condition, there is still a long way to go but some progress is being made.

Historical Background

  • Angelo DiGeorge. In the mid 1960's, Angelo DiGeorge noticed a similar combination of clinical features in some children. He named the syndrom after himself. The symptoms that he recognised were hypoparathyroidism, underdeveloped thymus, conotruncal heart defects and a cleft lip/palate. [5]
  • 'Robert Shprintzen described patients with similar symptoms (cleft lip, heart defects, absent or underdeveloped thymus, hypocalcemia) and named the group of symptoms as velo-cardio-facial syndrome. [6]
  • 1980s technology develops to identify that these patients have part of a chromosome missing. [7]




Dianostic Tests

Diagnostic Test How it works Relevance to DiGeorge
Fluorescence in situ hybridisation (FISH) [8] FISH is a technique that attaches DNA probes that have been labeled with fluorescent dye to chromosomal DNA. When viewed under fluorescent light, the labelled regions will be visible. This test allows for the determination of whether or not chromosomes or parts of chromosomes are present. This procedure differs from others in that the test does not have to take place during cell division. [9] FISH is a significant test used to confirm a DiGeorge diagnosis. Since the syndrome features a loss of part or all of chromosome 22, the probe will have nothing or little to attach to. This will present as limited fluorescence under the light and the diagnostician will determine whether or not the patient has DiGeorge. As with any testing, it is difficult to rely on one result to determine the condition. The patient must present with certain clinical features and then FISH is used to confirm the diagnosis.
Based on symptoms DiGeorge patients often have similar symptoms even though it is a condition that affects a number of the body systems. These similarities can be used as early tools in diagnosis. Practitioners would be looking for features such as the following:
  • Hypoparathyroidism resulting in hypocalcaemia
  • Poorly developed or missing thyroid presenting as immune system malfunctions
  • Small heads
  • Kidney function problems
  • Heart defects
  • Cleft lip/ palate [10]
When considering a patient with a number of the traditional symptoms of DiGeorge, a practitioner would not rely solely on the clinical symptoms. It would be necessary to undergo further tests such as FISH to confirm the diagnosis. In addition, with modern technology and prenatal care advancing, it is becoming less common for patients to present past infancy. Many cases are diagnosed within pregnancy or soon after birth due to the significance of the heart, thyroid and parathyroid.
Ultrasound An ultrasound is a prenatal care test to determine how the fetus is developing and whether or not any abnormalities may be present. The machine sends high frequency sound waves into the area being viewed. The sound waves reflect off of internal organs and the fetus into a hand held device that converts the information onto a monitor to visualize the sound information. Ultrasound is a non-invasive procedure. [11] Ultrasound is able to pick up any abnormalities with heart beats. If the heart has any abnormalities is will lead to further investigations to determine the nature of these. It can also be used to note any physical abnormalities such as a cleft palate or an abnormally small head. Like diagnosis based on clinical features, ultrasound is used as an early indication that something may be wrong with the fetus. It leads to further investigations.
Amniocentesis amniotic fluid prenatal
BACS- on beads technology test test

Clinical Manifestations


Further research possibilities



2011 Projects: Turner Syndrome | DiGeorge Syndrome | Klinefelter's Syndrome | Huntington's Disease | Fragile X Syndrome | Tetralogy of Fallot | Angelman Syndrome | Friedreich's Ataxia | Williams-Beuren Syndrome | Duchenne Muscular Dystrolphy | Cleft Palate and Lip