Jacquelyn Zirbes, DNP, RN, CNP, CCRC
Stanford University Cystic Fibrosis Center
Lucile Packard Children’s Hospital

Discovery of the ∆F508
CFTR Mutation
Research teams led by
Lap-Chee Tsui, Jack Riordan, and Francis Collins

Newborn Screening Definition *
• Population-based public health program applying preventive medicine in defined regions to reduce infant morbidity and mortality from certain biochemical and genetic disorders by using presymptomatic detection/diagnosis with dried blood specimens from newborns analyzed in central laboratories employing automated procedures linked to clinical follow-up systems.

Principles of Achieving Better Outcomes Through
Newborn Screening
Screening/Follow-up Diagnosis
Effective Therapy
Birth
Preclinical Stage
Biologic
Onset
Symptomatic
Onset
Life Threatening
Or Irreversible
Disease
Death
Time/Event

Diagnosis Through Newborn Screening
This ~0.4 ml dried blood specimen supports numerous screening tests!

CF Center
Dedicated Line
NBS Coordinator
NBS State Program:
Positive Screen
Primary Care Provider
Family

California 4-Step CF NBS Model
1. Immunoreactive Trypsinogen assay (cut-off = 1.6%; projected sensitivity= 95.7%)
2. DNA analysis with a panel of 40 CFTR mutations
(15/23 ACMG* mutations + “minority” alleles)
3. DNA scanning  sequencing by Ambry
4. Sweat test when 2 or more mutations detected

California 4-Step Method’s Goals
1. Use initial dried blood specimen only
2. Focus on “severe” cases of cystic fibrosis
3. Identify at least 90% of Hispanic, White, and Black cases
4. Reduce burden of false positives & negatives, sweat tests, and costs
5. Achieve efficient reporting of NBS test results
6. Follow-up and diagnosis of positive screens at CF
Centers

SCREENING ≠ DIAGNOSIS
(exception: DF
508
/DF
508
= CF)

Definition of “Screening for Early
Detection of Disease”
“The screening procedure itself does not diagnose illness.”
“Those who test positive are sent for further evaluation by a subsequent diagnostic test or procedure to determine whether they do in fact have the disease.”
Hennekens and Buring, Epidemiology in Medicine, p327

California Minimum Guidelines
1 .
Preparation for Sweat Chloride Test
2. Sweat Chloride Test
3. Laboratory testing at first CF Center visit
4. Family Studies
5. Interpretation of Sweat Chloride Test
Results

• 210 infants identified
• 13 CF Centers
• 27 LPCH
ΔF508/ ΔF508
1
ΔF508/other
18 other/other
8

General Principle: genotype determines phenotype
(e.g., pancreatic insufficiency vs sufficiency in CF)
But, gene modifiers and extrinsic factors contribute also
In metabolic disorders such as PKU, mild (non-classical) cases can occur
In CF, genotype alone does not determine the pulmonary phenotype
* Zielenski J and Tsui LC, Ann Rev Genet 1995; 29:777-807

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California Genetic Disease Screening Program
Children’s Hospital of Central California
Children’s Hospital of Los Angeles
Children's Hospital and Research Center at Oakland
Kaiser Permanente Southern California
Loma Linda University Medical Center
Miller Children's at Long Beach Memorial Medical
Center
Stanford University
Sutter Sacramento Medical Center
University of California San Diego
University of California San Francisco
Ventura County Medical Center

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Frank Accurso, MD
University of Colorado
Phil Farrell, MD, PhD
University of Wisconsin
Paul Quinton, PhD
University of California San Diego
Jeff Wine, PhD
Stanford University

In a well defined cohort of newborns with fully identified CFTR mutations determine:
 1. The feasibility of applying a uniform infant preparation protocol for sweat testing that
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 includes salt supplementation and adequate fluid intake guidelines
2. The genotypic determinants of sweat chloride concentration and its longitudinal changes.
3. The effect of fluid and electrolyte balance on sweat chloride results

-Primary Outcome Measure
 Sweat chloride concentration at diagnosis.
We hypothesize that under the baseline conditions created by the preparation protocol sweat chloride will unequivocally discriminate between varying levels of CFTR dysfunction.

Secondary Outcomes
 Serum aldosterone, urinary and serum electrolytes.
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Serum IRT
Longitudinal changes in sweat chloride
Longitudinal changes in clinical parameters during the first 2 years of life to gain

Inclusion criteria:
 1) Positive California CF newborn screening result (2 CFTR
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 mutations identified).
2) Post-menstrual age ≥ 36 weeks
3) Age at time of first sweat test ≥ 2 weeks old and ≤ 16 weeks old
4) Weight at time of sweat test ≥ 2 Kg
Exclusion criteria:
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1) NICU Hospitalization at the time of diagnosis.
2) Requiring IV fluids and/or TPN at the time of test.
3) Diagnosis of hypothyroidism or other endocrinologic/metabolic abnormality.
4) Presence of any other active medical condition (e.g. congenital heart, liver, or renal disease) that in the opinion of the CF Center would interfere with reliable sweat testing.

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Study participation for approximately 2 years
Patients will be evaluated 5 times over the 2 year period
Family will receive salt supplementation kit
(salt packets, instructions and educational material) in anticipation of study visit

Time
Salt Kit
Sweat
Serum
Urine
Clinical
Measures
Micro
Stool
Pre-Visit Visit 1
Phone
Result
X
Initial
Diagnostic
X
X
X
X
X
Visit 2
1 month post visit 1
X
X
VISIT
Visit 3
6 (± 1) mos. old
X
X
X
X
X
X
X
X
X
X
Visit 4
12 (± 1) mos. old
X
X
X
X
X
Visit 5
24 (± 1) mos. old
X
X
X
X
X
X X

• CF Foundation Consensus Guidelines are still evolving
• Need to develop a collaborative care model with PCP- subspecialist partnership
• An evidence based medicine strategy is very difficult to develop
• Thus, prudent principles of Dx → Rx based on need should be followed
• Set high standards such as > 50th percentile growth and normal PFT’s
• But, avoid overly aggressive clinical management (primum
non nocere)

Initiate CF center care in newborns
Provide genetic counseling
Prevent severe malnutrition
• Vitamin E deficiency (hemolytic anemia)
• Vitamin A deficiency
• Essential fatty acid deficiency
• Protein energy malnutrition *
• Growth failure
Prevent hyponatremia/hypochloremia
• Salt loss in sweat *
• Associated with breast feeding
Prevent early progression of lung disease
• Recurrent bacterial infections
• Obstructive pulmonary disease
• Atelectasis with mucus plugs
* Potentially fatal

1. CF patients are generally well nourished at birth
2. PI will develop in ~90% of patients by ~1 year
3. Severe malnutrition will develop in ~50% untreated
4. PI can be anticipated and malnutrition prevented
5. Long term benefits of normal nutrition are significant

1. The CF lung is normal at birth, but not for long.
2. Lung disease often develops as early as 2 months.
3. Pseudomonas aeruginosa (PA) colonization may occur in ~1/3 of undiagnosed patients.
4. Transformation from PA to mucoid PA is the greatest long term risk for children.

• An established trend of early diagnosis through NBS
• A paradigm shift in therapeutic strategy from the 3 I’s to the 3 P’s
• No longer dominated by intervention in individuals with illnesses
• But prevention in presymptomatic patients
– Prevention of early deaths
– Prevention of salt depletion
– Prevention of malnutrition and growth failure
– Prevention of “cross-infection”
– Prevention of chronic PA and early mPA
– Prevention of hospitalizations
– Prevention (eventually) of lung disease

Summary of Advantages of CF Newborn
Screening
• Avoid diagnostic quest
• Early, specific and proper care
• Proactive strategy of care
• Prevention
• Improved quality of life
• Improved parental learning
• Reduce costs
• Prevent malnutrition and micronutrient deficiencies
• Reduce risk of cognitive dysfunction

The Stanford Cystic Fibrosis Center at
Lucile Packard Children’s Hospital
• Individual Treatment Plan
• Collaborative Care
• Interdisciplinary Team
• Standards of CF Care
• Family Centered Care
• Emphasis on Family and Primary Provider Education
• Research