Autosomal dominant immunodeficiency

1. DIGEORGE SYNDROME
Created By- Gaurav(1917)
Department of Microbiology
MDU ROHTAK

2. What is DiGeorge Syndrome?
• Also known as 22q11.2 deletion syndrome or T cell defect
• Caused when a small part of chromosome 22 is missing.
• Autosomal dominant immunodeficiency
• Result in poor development of several body system

3. Causes of DiGeorge syndrome
• Caused by deletion of embryo of a region on chromosome 22 containing
up to 50 genes, with the T-box transcription factor (TBX1) thought to be
most influential.
• TBX1 highly expressed during particular stages of embryonic development,
when facial structures, heart, thyroid, parathyroid, and thymus tissues are
forming
• For this reason, the syndrome also called the third and fourth pharyngeal
pouch syndrome to reflect its precise embryonic origion.

4. CATCH 22 SYNDROME
It is not an actual syndrome, rather a type of disorder
• Cardiac effect (tetralogy of fallot)
• Abnormal facial features
• Thymic hypoplasia
• Cleft palate and claft lip
• Hypocalcaemia (PTH absent)
• 22 –refers to the chromosome number

5. Heart Defect
• Causes heart defects that could result in
an insufficient supply of oxygen-rich
blood.
• defects may include a hole between the
lower chambers of the heart
(ventricular septal defect)
• Lead to Truncus arteriosus (only one
large vessel, rather than two vessels,
leading out of the heart )
• Or Tetralogy of Fallot (combination of
four abnormal heart structures) Truncus arteriosus Tetralogy of Fallot

6. Thymic Hypoplasia
• It occurs in very rare cases of complete DGS, where no thymic tissue
develops, severe depression of T-cell numbers.
• Which cause poor antibody responses due to lack of T-cell help leave
patients susceptible to all types of opportunistic pathogens.
• Thymic transplantation and passive antibody treatment can be used to treat
these individuals.

7. Hypoparathyroidism
• 22q11.2 deletion syndrome can cause smaller
than normal parathyroid glands that secrete
too little parathyroid hormone (PTH), leading
to hypoparathyroidism.
• This result to low levels of
calcium(hypocalcaemia) and high levels of
phosphorus in the blood.
Parathyroid glands

8. Distinct facial features
These may include :-
• Small, low-set ears
• Short width of eye openings (palpebral fissures)
• Hooded eyes
• Relatively long face
• An enlarged nose tip (bulbous)
• Short or flattened groove in the upper lip.

9. OTHER COMPLICATIONS
• Learning and behaviorur problems – including delays in learning to walk or
talk, learning disabilities like attention deficit hyperactivity disorder(ADHD)
or Autism
• Speech hearing problems – incluiding temporary hearing loss due to frequent
ear infections, being slow to start talking and having a "nasal-sounding"
voice
• Being slow to start talking and having a "nasal-sounding" voice

10. Treatment
• In the majority of DGS patients, in which some residual thymic tissue
develops and functional T cells are found in the periphery.
• Treatments to avoid bacterial infection, such as antibiotics, are often
sufficient to compensate for the immune defects.
• There's currently no cure for complete DiGeorge syndrome.
• Children and adults with the condition will be closely monitored to check for
problems, and these can be treated as they happen, if needed.

11. References
• Kuby Immunology 7th Edition 2013
• https://www.mayoclinic.org/diseases-conditions/digeorge-
syndrome/symptoms-causes/syc-20353543
• https://www.nhs.uk/conditions/digeorge-syndrome/
• https://en.wikipedia.org/wiki/DiGeorge_syndrome