The Role of Prox1 during Mouse Pancreas Organogenesis

The pancreas is a mixed (exocrine and endocrine) glandular organ that is important for food digestion and glucose homeostasis. Developmental anomalies or disorders that affect normal pancreas homeostasis may cause various life-threatening diseases such as pancreatitis, diabetes, cystic fibrosis, and pancreatic cancer. In the past two decades, an increasing number of studies have begun to unravel the molecular and cellular mechanisms regulating mammalian pancreas organogenesis. The information extracted from these studies should be valuable both, to better understand the etiology of some pancreatic diseases, and to design new therapeutic tools to cure those diseases. A recent study reported expression of the homeodomain transcription factor Prox1 in the presumptive pancreatic region of mouse embryos1. This finding raised the possibility that, similar to other tissues, proper pancreas development requires the function of Prox1. The studies of my Ph.D thesis sought to uncover the role of Prox1 during mouse pancreas organogenesis. First, the expression of Prox1 in the developing pancreas was thoroughly characterized and the pancreatic tissues of Prox1-nullizygous embryos were analyzed (Chapter 2). Second, since Prox1-nullizygous embryos die at around embryonic day (E) 14.5, we generated a (Prox1loxP/loxP novel mouse model ;Pdx1.Cre) with conditional inactivation of Prox1 in pancreatic progenitors, to investigate whether loss of Prox1 function affects late aspects of pancreas organogenesis (Chapter 3). Third, upon identifying Opn as a novel pancreatic gene, we performed an extensive analysis of its expression in the pancreas of mouse embryos and adults and characterized this organ of Opn-nullizygous mice (Chapter 4)

Thyroid disease and cervical dystonia

To determine the incidence of phosphorylated a-synuclein (p-syn) in skin nerves in very old subjects who are prone to developing incidental Lewy bodies, we prospectively performed skin biopsies on 33 elderly subjects, including 13 (>85 years old) and 20 patients (>70 years) suspected of having an acquired small fiber neuropathy. All subjects underwent neurological examination prior to the biopsy. Two screened female subjects (ages 102 and 98 years) were excluded from the study because they showed evidence of a slight bradykinetic-rigid extrapyramidal disorder on neurological examination and were not considered healthy; both showed p-syn in skin nerves. We did not identify p-syn in skin nerves in the remaining 31 subjects. A PubMed analysis of publications from 2013 to 2023 disclosed 490 healthy subjects tested for skin p-syn; one study reported p-syn in 4 healthy subjects, but the remaining subjects tested negative. Our data underscore the virtual absence of p-syn in skin nerves of healthy controls, including those who are very elderly. These data support skin biopsy as a highly specific tool for identifying an underlying synucleinopathy in patients in vivo

Dystonia and Tremor: A Cross-Sectional Study of the Dystonia Coalition Cohort

OBJECTIVE: To assess the clinical manifestations and predictors of different types of tremors in individuals with different types of isolated dystonia. METHODS: Clinical manifestations of tremor were assessed in a multicenter, international cross-sectional, cohort study of 2,362 individuals with all types of isolated dystonia (focal, segmental, multifocal, and generalized) recruited through the Dystonia Coalition. RESULTS: Methodical and standardized assessments of all participants in this cohort revealed the overall prevalence of any type of tremor was 53.3%. The prevalence of dystonic tremor varied from 36.9% to 48.4%, depending on criteria used to define it. To identify the factors associated with tremors in dystonia, the data were analyzed by generalized linear modeling and cluster analyses. Generalized linear modeling indicated 2 of the strongest factors associated with tremor included body region affected by dystonia and recruitment center. Tremor was also associated with severity of dystonia and duration of dystonia, but not with sex or race. The cluster analysis distinguished 8 subgroups within the whole cohort; defined largely by body region with dystonia, and secondarily by other clinical characteristics. CONCLUSION: The large number of cases evaluated by an international team of movement disorder experts facilitated the dissection of several important factors that influence the apparent prevalence and phenomenology of tremor in dystonia. These results are valuable for understanding the many differences reported in prior studies, and for guiding future studies of the nosology of tremor and dystonia

Current Guidelines for Classifying and Diagnosing Cervical Dystonia: Empirical Evidence and Recommendations

Background: The dystonias are phenotypically and etiologically heterogenous disorders. Many proposals and a consensus recommendation have been provided for the diagnosis and classification of the dystonias, but these recommendations serve only as general guidelines. Current diagnosis and classification may still depend on clinical judgment causing different opinions. Objective: To delineate clinical features used by movement disorder specialists in the diagnosis and classification of isolated focal cervical dystonia, and to develop recommendations for a more consistent approach to classification according to anatomical regions involved. Methods: Cross-sectional data for subjects diagnosed with isolated dystonia were acquired from the Dystonia Coalition, an international, multicenter collaborative research network. Data from many movement disorder specialists were evaluated to determine how diagnoses of cervical dystonia related to their recorded examinations. Cases were included if they were given a diagnosis of focal cervical dystonia. Cases were also included if they had dystonia of the neck on exam, but were given an alternative diagnosis such as segmental dystonia. Results: Among 2916 subjects with isolated dystonia, 1258 were diagnosed with focal cervical dystonia. Among these 1258 cases, 28.3% had dystonia outside of the neck region. Regions involved outside of the neck included the shoulder, larynx, and sometimes other regions. Analysis of the results pointed to several factors that may influence specialists\u27 use of current diagnostic guidelines for making a diagnosis of isolated focal cervical dystonia including varied interpretations of involvement of nearby regions (shoulder, larynx, platysma), severity of dystonia across different regions, and occurrence of tremor in different regions. Conclusions: Although focal cervical dystonia is the most common type of dystonia, a high percentage of subjects given this diagnosis had dystonia outside of the neck region. This observation points to the need for more specific guidelines for defining this common disorder. Such guidelines are proposed here

Current Guidelines for Classifying and Diagnosing Cervical Dystonia: Empirical Evidence and Recommendations

Background: The dystonias are phenotypically and etiologically heterogenous disorders. Many proposals and a consensus recommendation have been provided for the diagnosis and classification of the dystonias, but these recommendations serve only as general guidelines. Current diagnosis and classification may still depend on clinical judgment causing different opinions. Objective: To delineate clinical features used by movement disorder specialists in the diagnosis and classification of isolated focal cervical dystonia, and to develop recommendations for a more consistent approach to classification according to anatomical regions involved. Methods: Cross-sectional data for subjects diagnosed with isolated dystonia were acquired from the Dystonia Coalition, an international, multicenter collaborative research network. Data from many movement disorder specialists were evaluated to determine how diagnoses of cervical dystonia related to their recorded examinations. Cases were included if they were given a diagnosis of focal cervical dystonia. Cases were also included if they had dystonia of the neck on exam, but were given an alternative diagnosis such as segmental dystonia. Results: Among 2916 subjects with isolated dystonia, 1258 were diagnosed with focal cervical dystonia. Among these 1258 cases, 28.3% had dystonia outside of the neck region. Regions involved outside of the neck included the shoulder, larynx, and sometimes other regions. Analysis of the results pointed to several factors that may influence specialists' use of current diagnostic guidelines for making a diagnosis of isolated focal cervical dystonia including varied interpretations of involvement of nearby regions (shoulder, larynx, platysma), severity of dystonia across different regions, and occurrence of tremor in different regions. Conclusions: Although focal cervical dystonia is the most common type of dystonia, a high percentage of subjects given this diagnosis had dystonia outside of the neck region. This observation points to the need for more specific guidelines for defining this common disorder. Such guidelines are proposed here

Dystonia and Tremor: A Cross-Sectional Study of the Dystonia Coalition Cohort

OBJECTIVE: To assess the clinical manifestations and predictors of different types of tremors in individuals with different types of isolated dystonia. METHODS: Clinical manifestations of tremor were assessed in a multicenter, international cross-sectional, cohort study of 2,362 individuals with all types of isolated dystonia (focal, segmental, multifocal, and generalized) recruited through the Dystonia Coalition. RESULTS: Methodical and standardized assessments of all participants in this cohort revealed the overall prevalence of any type of tremor was 53.3%. The prevalence of dystonic tremor varied from 36.9% to 48.4%, depending on criteria used to define it. To identify the factors associated with tremors in dystonia, the data were analyzed by generalized linear modeling and cluster analyses. Generalized linear modeling indicated 2 of the strongest factors associated with tremor included body region affected by dystonia and recruitment center. Tremor was also associated with severity of dystonia and duration of dystonia, but not with sex or race. The cluster analysis distinguished 8 subgroups within the whole cohort; defined largely by body region with dystonia, and secondarily by other clinical characteristics. CONCLUSION: The large number of cases evaluated by an international team of movement disorder experts facilitated the dissection of several important factors that influence the apparent prevalence and phenomenology of tremor in dystonia. These results are valuable for understanding the many differences reported in prior studies, and for guiding future studies of the nosology of tremor and dystonia

A Multi-center Genome-wide Association Study of Cervical Dystonia

Background: Several monogenic causes for isolated dystonia have been identified, but they collectively account for only a small proportion of cases. Two genome-wide association studies have reported a few potential dystonia risk loci; but conclusions have been limited by small sample sizes, partial coverage of genetic variants, or poor reproducibility. Objective: To identify robust genetic variants and loci in a large multicenter cervical dystonia cohort using a genome-wide approach. Methods: We performed a genome-wide association study using cervical dystonia samples from the Dystonia Coalition. Logistic and linear regressions, including age, sex, and population structure as covariates, were employed to assess variant- and gene-based genetic associations with disease status and age at onset. We also performed a replication study for an identified genome-wide significant signal. Results: After quality control, 919 cervical dystonia patients compared with 1491 controls of European ancestry were included in the analyses. We identified one genome-wide significant variant (rs2219975, chromosome 3, upstream of COL8A1, P-value 3.04 × 10−8). The association was not replicated in a newly genotyped sample of 473 cervical dystonia cases and 481 controls. Gene-based analysis identified DENND1A to be significantly associated with cervical dystonia (P-value 1.23 × 10−6). One low-frequency variant was associated with lower age-at-onset (16.4 ± 2.9 years, P-value = 3.07 × 10−8, minor allele frequency = 0.01), located within the GABBR2 gene on chromosome 9 (rs147331823). Conclusion: The genetic underpinnings of cervical dystonia are complex and likely consist of multiple distinct variants of small effect sizes. Larger sample sizes may be needed to provide sufficient statistical power to address the presumably multi-genic etiology of cervical dystonia. © 2021 International Parkinson and Movement Disorder Society

A Multi-center Genome-wide Association Study of Cervical Dystonia

BACKGROUND: Several monogenic causes for isolated dystonia have been identified, but they collectively account for only a small proportion of cases. Two genome-wide association studies have reported a few potential dystonia risk loci; but conclusions have been limited by small sample sizes, partial coverage of genetic variants, or poor reproducibility. OBJECTIVE: To identify robust genetic variants and loci in a large multicenter cervical dystonia cohort using a genome-wide approach. METHODS: We performed a genome-wide association study using cervical dystonia samples from the Dystonia Coalition. Logistic and linear regressions, including age, sex, and population structure as covariates, were employed to assess variant- and gene-based genetic associations with disease status and age at onset. We also performed a replication study for an identified genome-wide significant signal. RESULTS: After quality control, 919 cervical dystonia patients compared with 1491 controls of European ancestry were included in the analyses. We identified one genome-wide significant variant (rs2219975, chromosome 3, upstream of COL8A1, P-value 3.04 × 10(-8) ). The association was not replicated in a newly genotyped sample of 473 cervical dystonia cases and 481 controls. Gene-based analysis identified DENND1A to be significantly associated with cervical dystonia (P-value 1.23 × 10(-6) ). One low-frequency variant was associated with lower age-at-onset (16.4 ± 2.9 years, P-value = 3.07 × 10(-8) , minor allele frequency = 0.01), located within the GABBR2 gene on chromosome 9 (rs147331823). CONCLUSION: The genetic underpinnings of cervical dystonia are complex and likely consist of multiple distinct variants of small effect sizes. Larger sample sizes may be needed to provide sufficient statistical power to address the presumably multi-genic etiology of cervical dystonia