1. Confirmatory Testing Considerations
Beth Vogel, MS, CGC
Genetic Counselor
Newborn screening program
Wadsworth center
New york state department of health

2. Overview Implementation Short-term follow-up Case review meetings
Diagnostic testing

3. Implementation: Guidance
Partnership with clinicians
New York State SCID Consortium
9 external group members
National recommendations
Newborn Screening Translational Research Network, CLSI Guidelines

4. Implementation: Guidance
Discussion points for NBS and clinician group
Minimum standard confirmatory tests
Short-term follow-up
Diagnostic categories
Transplants
Algorithm changes
Detection of non-SCID disorders

5. Implementation: Education
Target hospitals and primary care providers
TREC assay is not well known!
Developed educational materials
Letter to hospitals
Phone consultations
NBS and Specialty Care Centers
WHAT IS A TREC?!

6. Short-term Follow-up Process
Eight Specialty Care Centers
Referral is called to primary care provider and specialty care center (SCC)
Diagnostic form completed by clinician

7. Case Review Meetings Identify topics for Consortium conference calls
Unusual cases
Identify need for new diagnostic categories
Algorithm changes
Correlation of laboratory findings and clinical outcomes

8. Case Review Meetings Maintain consistency in case closure Incidence
Algorithm changes
Long-term follow-up

9. Diagnostic Categories
From NBSTRN website:
SCID
Leaky SCID/Omenn syndrome
Variant SCID
Syndromes with T cell impairment
Secondary T cell lymphopenia other than preterm alone
Preterm alone

10. SCID Classic phenotype
<300 autologous T cells/μL
Emergent treatment required (transplant, gene therapy, enzyme replacement therapy)

11. Leaky SCID/Omenn Syndrome
Low T cell count
3oo to 1500 T cells/μL
Requires treatment (transplant, gene therapy, enzyme replacement therapy)
Omenn syndrome
Erythrodermia, hepatosplenomegaly, eosinophilia, elevated IgE, restricted TCR diversity of T cells

12. Variant SCID Moderately decreased T cell counts
May not require transplant

13. Syndromes with T Cell Impairment
DiGeorge syndrome/22q11.2 deletion syndrome
CHARGE syndrome
Jacobsen syndrome
RAC2 defect
DOCK8 deficiency
Ataxia telangiectasia
VACTERL association
Barth syndrome
TAR syndrome
Down syndrome
Ectrodactyly ectodermal dysplasia syndrome
Other

14. Secondary T Cell Lymphopenia Other Than Preterm Alone
Birth defects
Gastroschisis, intestinal lymphangiectasia, congenital heart defects, cardiac surgery +/- thymectomy
Metabolic disorder, degenerative neuromuscular disease

15. Preterm Alone <37 weeks gestation
TREC copy number typically improves over time
If TRECs are undetectable, then full work-up warranted regardless of gestational age

16. Idiopathic T-cell Lymphopenia
Non-SCID
No congenital anomalies
Low T-cells that require clinical monitoring

17. Diagnostic Testing: Complete Blood Count
Lymphocytes
T cells = 70% of circulating lymphocytes
Proposed as a method to screen for SCID prior to current technologies
“ALC (absolute lymphocyte count) <2500/uL in early infancy requires further evaluation”
R. Buckley, MD

18. Diagnostic Testing: Flow Cytometry
Evaluation of lymphocyte subpopulations
Normal ranges vary by age

19. Diagnostic Testing: Flow Cytometry
CD = Cluster of differentiation

20. Diagnostic Testing: Flow CytometryCD
Cell Type
CD3
T cells
CD4
Helper T cells
CD8
Suppressor T cells
CD19
B cells
CD16CD56
NK cells

21. Diagnostic Testing: Flow Cytometry

22. Diagnostic Testing: Lymphocyte Proliferation to Mitogens
Test of T-cell function
Less sensitive, but more specific test of T-cell function
Culture human peripheral blood mononuclear cells with plant lectin mitogens)
phytohemagglutinin (PHA), pokeweed mitogen (PWM), concanavalin (conA)
Response highest in newborns and decreases with age

23. Diagnostic Testing: Mitogens

24. Diagnostic Testing: Naïve and Memory T-cell Count
Not typically included as part of standard flow cytometry
CD45RA+ = Naive
CD45RO+ = Memory

25. Genetic Testing Multiple genes
Mutation info often not needed before transplant
May be important if diagnosis is unclear
Important for genetic counseling
45% of SCID cases are X-linked (IL2RG-related)
Remainder of the cases are recessive

26. Diagnostic Form

27. Diagnostic Form

28. References
Hicks MJ, Jones JK, Thies AC, et al: Age-related changes in mitogen-induced lymphocyte function from birth to old age. Am J Clin Pathol 1983;80:
Baker M, Grossman W, Laessig R, et al. Development of a routine newborn screening protocol for severe combined immunodeficiency. J Allergy Clin Immunol. 2009; 124:
Puck M, et al. Population-based newborn screening for severe combined immunodeficiency: Steps toward implementation. J Allergy Clin Immunol. 2007; 120 (4):
Chan K, Puck J. Development of population-based newborn screening for severe combined immunodeficiency. J Allergy Clin Immunol. 2005; 115:
Comeau A, Hale J, Pai S, et al. Guidelines for implementation of population-based newborn screening for severe combined immunodeficiency. J Inherit Metab Dis. 2010
Buckley RH. The long quest for neonatal screening for severe combined immunodeficiency. Clinical Reviews in Allergy and Immunology. 2012
Adeli MM and Buckley RH. Why newborn screening for severe combined immunodeficiency is essential: a case report. Pediatrics. 2010; 126(2):e465-e469.
Chase NM, Verbsky JW, Routes JM. Newborn screening for SCID: three years of experience. Ann. N.Y. Acad. Sci. 2011; 1238:
Buckley RH, Transplantation of hematopoietic stem cells in human severe combined immunodeficiency: longterm outcomes. Immunol Res. 2011; 49:

29. Thank you
Questions?