# Presentation: 677777

## Challenges and Opportunities of Incorporating                 Genetics into MCH Studies

**Session: ****Genetics, Genomics, Epidemiology, and MCH**_ _
***12th Annual Maternal and Child Health Epidemiology Conference, Atlanta, GA***

**Sonja A Rasmussen, MD, MS**
**National Center on Birth Defects and Developmental Disabilities, Centers for                   Disease Control and Prevention**

## National Birth Defects                                    Prevention Study (NBDPS)

**National Birth Defects                                    Prevention Study (NBDPS)**

**Case-control study of major birth defects**
**Evaluate genetic and environmental risk factors**
**Enrollment began with births on or after 10/1/97**

**CA**

**UT**

**TX**

**AR**

**GA**

**NC**

**NY**

**MA**

**IA**

## Components of NBDPS 

**Case ascertainment and review**
**Maternal interview**
**DNA collection on infant, mother, father**

*Yoon et al., Public Health Rep 116:32-40, 2001*
*Rasmussen et al., Teratology 66(4):177-84, 2002*
*Rasmussen et al., Birth Defects Res Part A Clin Mol Teratol 67:193-201, 2003*

**Notes:**
3 Main Components of NBDPS
Clinical database 
Standard, detailed case definitions
Review of records by a clinical geneticist
Maternal interview
Computer assisted telephone interview
Maternal health, medications, pregnancy history, nutrition, tobacco, alcohol, occupation, demographics, water, and family history
Most responses automatically coded during interview
Buccal cell (DNA) collection
Mother, father, infant

## Why Study Genetic Factors and Gene-Environment Interaction?

**Results in improved understanding of etiology  **
**Allows identification of:**
***populations at high risk *****(susceptible genotype)**
***modifiable risk factors *****                                                 (environmental exposures)**
**Increases opportunities for prevention**

## Important Considerations             in the Incorporation of              Genetics into MCH Studies

**Selecting source of specimens**
**Maximizing participation rates**
**Human subjects-related issues**
**Informed consent for studies of genes not yet identified**** **
**Disclosure of individual results**
**Choosing genes for analysis and analytic approach to be used**

## Selecting Source of Specimens

**Venous blood**
**Buccal cells (collected by swab, cytobrush, FTA****®**** cards, mouthwash, saliva)**
**Newborn blood spots (previously collected)**

**Notes:**
Buccal swabs – swab coated with cellular material is allowed to dry and then placed in a sealed plastic tube.
Saliva – patients sent a plastic vial that contains a small cotton roll – similar to that used by dentists.  Participants told to chew the cotton roll for 30-45 seconds before placing it in the plastic vial.
FTA cards – fresh material is transferred from the applicator onto the indicating circle on the FTA card.  This circle changes color when sample is applied.  When circular collection area is completely filled, ~100 discs for analysis are available.  Recently a method for elution of DNA from the paper has been published
Mouthwash and FTA cards higher DNA yields that buccal swabs, cytobrush
According to a recent survey (Olney et al.), newborn blood spots were stored for more than 6 months in about half of the states.   Over a quarter of the states had used the newborn blood spots for epidemiologic studies – most have not been linked to identifiers.

## Issues to Consider when Selecting Source of Specimens

**Issues to Consider when Selecting Source of Specimens**

**Amount of DNA**
**Quality of DNA**
**Other possible uses of sample source**
**Cost/ease of collection**
**Age of participants**
**Impact on participation rates**

**Notes:**
Garcia-Closas – mouthwash produced consistently better yields than brushes, higher quality DNA (King et al.)

## NBDPS Source of Specimens

**Buccal cells collected by  cytobrush**

## Participation Rates for Interview                   and Buccal Cell Collection,                         NBDPS (Atlanta) 1999-2002

*Crider et al., Am J Epidemiol 164:805-12, 2006*_ _

## Factors Associated with Higher Participation in Buccal Cell Collection

**Non-Hispanic white race/ethnicity**
**English-language (vs. Spanish) interview**
**Receipt of a redesigned mailing packet and additional $20 incentive**
**Consumption of folic acid**

*Crider et al., Am J Epidemiol 164:805-12, 2006*_ _

## “Blanket” consent
Periodic re-consent

**“****Blanket” consent**
**Periodic re-consent**

*Burke and Diekema, J Pediatr 149:S34-38, 2006*

## Study started in 1997 - biologics specimens to be used for decades
Plan to study hundreds of genetic factors – some not yet discovered, methods of study likely to change
Informed consent states that samples will be used to study genes that may play a role in birth defects causation

**Study started in 1997 - biologics specimens to be used for decades**
**Plan to study hundreds of genetic factors – some not yet discovered, methods of study likely to change**
**Informed consent states that samples will be used to study genes that may play a role in birth defects causation**

## For each genetic factor to be studied, investigator will submit gene one-pager to CDC IRB as protocol amendment for expedited review

**For each genetic factor to be studied, investigator will submit gene one-pager to CDC IRB as protocol amendment for expedited review**

## Proposed genetic research and justification of why testing is important 
Is this test of clinical significance? 
If yes, what additional efforts that concern human subjects protection will be made by the investigators? 
Any other information related to this research that may be important to IRB

**Proposed genetic research and justification of why testing is important **
**Is this test of clinical significance? **
**If yes, what additional efforts that concern human subjects protection will be made by the investigators? **
**Any other information related to this research that may be important to IRB**

## Approaches to Disclosure of Individual Genetics Results

**Research-focused approach – results should generally not be offered because goal of research is to provide generalizable (not individual) knowledge**
**Autonomy-focused approach – all results should be offered because individuals have a right to information about themselves**

*Ravitsky and Wilfond, Am J Bioeth 6:8-17, 2006*

## Reporting Genetic Results in Research Studies: Recommendations

**Key criteria**
**Risk for disease should be significant**
**Disease should have important health implications (i.e., mortality, morbidity, significant reproductive implications)**
**Proven therapeutic or preventive interventions should be available**
**Final decision should be made with IRB approval after careful consideration of risks and benefits**

*NHLBI Working Group on Reporting Genetic Results in Research Studies*
*Bookman et al., Am J Med Genet A 140:1033-40, 2006 *

## Reporting Genetic Results in Research Studies: Recommendations (continued)

**Genetic test results should not be reported to study participants and their health care providers unless test was performed in a CLIA-certified laboratory**
**Counselor/consultant should be provided to explain nature of study, implications of participation, potential relevance of genetic results **
**Information on what to do with results should be summarized, preferably on a single page**

*NHLBI Working Group on Reporting Genetic Results in Research Studies*
*Bookman et al., Am J Med Genet A 140:1033-40, 2006 *

**Notes:**
Clinical Laboratory Improvement Amendments – CLIA – only results from CLIA-certified laboratories can be reported to patients or used in clinical care.  

## NBDPS Plans for Genetic Factors   of Clinical Significance

**Testing must be done in a CLIA-certified laboratory so results can be provided to study participants if desired**
**Study participants notified of summarized results of genetic factors with clinical significance by NBDPS newsletter**
**Participants can request results if desired**
**Informed consent form reflects this approach**

## Reporting Results to Study Participants: Additional Issues

**Reporting Results to Study Participants: Additional Issues**

**Unintended information may be revealed by genetic studies**
**Information on other family members**
**Non-paternity**
**Reporting individual results on children**** **

- 1, 2

- 2, 3

- 1, 1

## Choosing Genes for Analysis

**Candidate genes**
**Genome-wide studies**

**Notes:**
Predicted 20,000-25,000 genes and 10 million SNPs in the Human genome – how do you decide what to test?

## Candidate Gene Studies

**Candidate gene – a gene for which there is evidence of its possible role in the trait or disease that is under study**
**Based on previously reported associations in epidemiologic or family studies, biologic plausibility, expression or linkage studies, and other factors**

*Green and Moore, Birth Defects Res Part A Clin Mol Teratol*_* *_*76:798–810, 2006*

**Notes:**
Genes and SNPs to be analyzed are selected in advance on the basis of previously reported associations in epidemiologic or family studies, biologic plausibility, expression, linkage, and other factors – such as pathways for hypotheses – vascular pathogenesis of gastroschisis – study genes involved in vascular pathways – clotting, etc.

Advantages - Less costly, can be done with smaller numbers of cases, can focus on genes or pathways of interest
Disadvantages – must know something, will not identify novel genes 
More suited to hypothesis testing than hypothesis generation

## Genome-Wide Studies

**Linkage mapping**
**Genome-wide association studies**

*Hirschhorn and Daly, Nat Rev Genet 6:95-108, 2005*

**Notes:**
Linkage mapping – requires families – Genes are mapped by typing genetic markers in families to identify regions that are associated with disease or trait values within pedigrees more often than expected by chance.  This method has been successful for finding genes for Mendelian conditions, but not for most common diseases.  Probably because most common genetic variants only have modest effect on disease.
Genome-wide association studies – dense set of SNPs across the genome is genotyped to survey the most common genetic variation for a role in disease.  
Advantages – can provide new information about gene not previously suspected.
Disadvantages - need to genotype hundreds of thousands of SNPs, costly, need high sample size for adequate statistical power, problems with analyses – multiple comparisons  false positives – need way to screen results.

## Conclusions

**Incorporating genetics into MCH studies holds promise for better understanding of disease etiology and possibly improved primary prevention**
**Several considerations need to be taken into account when designing a study that incorporates genetics**

## Acknowledgments

**Margaret Honein**
**Mary Jenkins**
**Cynthia Moore**
**CDC and other participating IRBs**
**NBDPS Investigators in AR, CA, CDC, IA, MA, NC, NJ, NY, TX, UT**