Blood product use - possible DiGeorge syndrome
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DiGeorge Syndrome (DGS) is a heterogeneous condition. Complete DGS refers to infants with athymia who have a severe immune deficiency, affecting about ~1% of infants with 22q11 deletion. Most children with 22q11 deletion do not have severe immune deficiency and most require no special immunologic management.
Not all patients with DGS have 22q11 deletion; deletions in chromosome 10, mutations of CHD7, CHARGE, and prenatal exposure to isotretinoin or high glucose have been described as associations.
Infants with complete DGS have severe immune deficiency with significant risk of infection. They are also at risk of transfusion acquired graft versus host disease (TA-GVHD) from engraftment of lymphocytes present in transfusion of blood products. TA-GVHD is almost universally fatal. Irradiation of blood products ameliorates this risk by destroying lymphocytes.
Complete atypical DGS
Some infants with DGS develop "complete atypical DiGeorge". These infants present with an eczematous like rash, adenopathy, and hepatosplenomegaly, due to clonal proliferation of a few T cells. Infants who present with these manifestations require urgent paediatric immunology referral regardless of initial screening tests. If such infants require surgery blood products should be irradiated.
Manifestations of 22q11
Common cardiac defects in 22q11, and the frequency of 22q11 with given abnormalities include:
Table 1: Frequency of common cardiac defects in 22q11
|Frequency of Finding|
Tetralogy of Fallot
Interrupted aortic arch
Table 2: Frequency of the chromosome 22q11.2 deletion associated with the following cardiac anomalies
|Frequency of Deletion|
|Any cardiac lesion
Conotruncal cardiac anomaly
Interrupted aortic arch
Tetralogy of Fallot
Velopharyngeal insufficiency post adenoidectomy
0 - 6%
From: Kobrynski, Lancet 2007
Of patients with athymia about 80% will have hypocalcaemia due to hypoparathyroidism. Many may present with other manifestations needing surgical intervention in infancy, including craniofacial and skeletal abnormalities.
Investigation for possible DiGeorge Syndrome
Infants who have 22q11 deletion or other features suggesting DGS should undergo further investigation to determine if they have severe immunodeficiency. Investigations should include:
- Full blood count
- Lymphocyte subsets - this result can be available within 4 hours (but the test is not performed weekends / after hours). If there is urgency to getting the result (e.g. prior to surgery) then notify the lab
- Review of CXR for thymic shadow
Discuss any infant with abnormal results with the paediatric immunology service.
Infants born in NZ are screened for T cell lymphopenia by measuring T cell receptor excision circles (TREC), also known as Severe Combined Immune Deficiency (SCID) screening, on the newborn screening blood test. This result is usually available within 1 week.
Irradiation of cellular blood products (whole blood, RBC, and platelets) prevents lymphocyte function in the transfused product and prevents TA-GVHD. Decide whether irradiation is needed prior to surgery. See flow chart.
Infants with "complete atypical DiGeorge" (see Definitions above) require irradiated blood products for surgery.
If thymic tissue is present at surgery then no further investigation or particular management of transfusion is required.
If thymic tissue is absent and immunological status is unknown then urgently consult with a paediatric immunologist before commencing cardiopulmonary bypass with non irradiated blood.
Older children with 22q11 or other features of DiGeorge Syndrome may not necessarily need the same precautions. If there is uncertainty about immune status discuss with paediatric immunology.
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- Date last published: 08 August 2018
- Document type: Clinical Guideline
- Services responsible: Paediatric Intensive Care Unit
- Author(s): D Buckley, Jan Sinclair
- Owner: D Buckley
- Editor: Greg Williams
- Review frequency: 2 years
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