3q29 Microdeletion Syndrome: Phenotypic Differences between Urban and Rural Populations Open Access

Averbach, Hallie (Spring 2019)

Permanent URL: https://etd.library.emory.edu/concern/etds/6q182m09d?locale=en




3q29 Deletion Syndrome is a genetic syndrome resulting from a recurrent 1.6 Mb deletion on the long arm of chromosome 3 (Willatt, 2005; Ballif, 2008). The syndrome is rare, with a prevalence of about 1 in 30,000. It is host to several phenotypic outcomes, including autism spectrum disorder, heart defects, and intellectual disability (Baliff, 2008; Glassford et al., 2016). However, the phenotypic outcomes vary among the population, meaning that not everyone with 3q29 Deletion Syndrome is subject to the same phenotypic outcomes. Currently, researchers do not fully understand the reason behind this variability. It may be due to the underlying biological mechanisms associated with the deletion or other factors, such as environmental factors. Research efforts of 3q29 Deletion Syndrome are focused at Emory University through an online registry and an in-person study. The 3q29 Registry has identified 140 cases of 3q29 Deletion. Nineteen of these cases have undergone physical, behavioral, and intellectual assessments, as outlined in Murphy et al. (2018) to learn more about the 3q29 Deletion Syndrome phenotype.

Currently, neither the registry nor the in-person study consider how environmental exposures related to phenotypic outcomes associated with 3q29 Deletion Syndrome. Environmental exposures include exposures to chemicals from soil, air, and water, and other factors, like exposures to stress, nutrition, and access to care. Existing data supports the hypothesis that interaction between genetic factors and environmental exposures influences phenotypic outcomes (Eley et al., 2004; Kim-Cohen et al., 2006; Manuck and McCaffery, 2014). Understanding how the environment interacts with the 3q29 deletion and the associated 3q29 Deletion Syndrome could lead to insights on how environmental factors play a role in how the differences in phenotypic outcomes manifest among the population. By identifying potential environmental exposures related to 3q29 Deletion Syndrome at the broad level of urban versus rural living areas, assessing whether individuals with 3q29 Deletion Syndrome experience different health outcomes based on living area, and suggesting future environmental exposure studies in relation to 3q29 Deletion Syndrome, this analysis aims to develop a preliminary understanding of how environmental factors may play a role in health outcomes associated with 3q29 Deletion Syndrome.


Table of Contents

Table of Contents

Introduction                                                                                                                         1

3q29                                                                                                                          1

Background and prevalence                                                                          1

Phenotype                                                                                                     1

Diagnosis, surveillance, and treatment                                                         2

Past and current efforts to understand 3q29 deletion syndrome                   3

Gene-environment interaction                                                                                 3

Mental health                                                                                                4

Urban and rural settings                                                                                          6

Chemical exposures                                                                                      6

Air quality                                                                                                     7

Access to care                                                                                                7

Phenotypic outcomes                                                                                    7

Methods                                                                                                                                9

Registry                                                                                                                     9

Study sample                                                                                                            9

Variables                                                                                                                   10

Classification                                                                                                           11

Analysis plan                                                                                                           12

Results                                                                                                                                   13

Discussion                                                                                                                             15

Limitations                                                                                                                           17

Future directions                                                                                                                  18

Conclusions                                                                                                                          20

Bibliography                                                                                                                        22

References                                                                                                                           28

Tables and figures                                                                                                                29

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