Search

Introduction: Sexual dimorphism in pulmonary arterial hypertension (PAH) is attributed, in part, to estrogen signaling. 16α-hydroxyestrone (16αOHE) is considered a major contributor to PAH pathogenesis. Recent genetic studies have also suggested that deficiency of SOX17, an endothelial cell (EC)-specific transcription factor, contributes to PAH risk. While functional studies of SOX17 are absent, we hypothesized that 16αOHE contributes to PAH, in part, via, SOX17 downregulation. Methods/Results: Sox17 expression was reduced in 3 animal PAH models and in human pulmonary artery ECs (HPAECs) isolated from patients with PAH (vs controls). Inducible Tie2-specific Sox17 knockout ( Sox17 EC-/- ) mice exhibited increased right ventricular systolic pressure (RVSP), RV hypertrophy (RVH), and PA wall thickness (PAWT) after chronic hypoxia (CH) (Fig 1A). Inducible Tie2- Sox17 transgenic overexpressing ( Sox17 Tg ) mice attenuated CH-induced PH (Fig 1B). While not evident across murine sex, Sox17 expression was increased in baseline lungs from male compared to female rats. Supporting in silico evidence of estrogen response elements (ERE) on the SOX17 promoter, HPAECs exposed to 16αOHE reduced SOX17 expression and promoter luciferase activity via ERα, which was partly negated by serial ERE mutagenesis (Fig 1C ) . Lungs from ERα loss-of-function mutant rats (vs control) confirmed in vivo reductions of Sox17 expression. Sox17 Tg mice attenuated 16αOHE-mediated PH after CH (Fig 1D). To translate these data, we identified a functional coding SNP in the ESR1 gene (encoding ERα), rs746432, previously shown to reduce transcriptional activity of ERα. The SNP was associated with reduced pulmonary vascular resistance in patients with PAH (n=702, Fig 1E) in adjusted analyses. Conclusion: Validating genetic studies, SOX17 deficiency augments preclinical PAH. 16αOHE mediates PH development via downregulation of SOX17, linking SOX17 genetics with the observed sexual dimorphism.

Introduction: Pediatric pulmonary arterial hypertension (PAH) is a multifactorial pulmonary vascular disease with high mortality. Endostatin (ES), an angiogenic inhibitor, is associated with disease severity and mortality in adults with PAH and poor lung growth in children. Hypothesis: Increased ES is associated with worse disease severity and outcomes in pediatric PAH. Methods: Serum ES levels were measured in two cohorts of pediatric PAH (IPAH, FPAH and APAH) patients; the cross-sectional CCHMC PAH Biobank (PAHB, N=175) and a longitudinal cohort from Children’s Hospital of Colorado (CHC, N=61). Outcomes included medical therapy, functional and hemodynamic measures, and survival (death, transplant, palliative shunt). Adjusted logistic and linear regressions and Kaplan-Meier analysis were used to assess the relationship between ES and clinical outcomes. Results: In both cohorts, ES was significantly higher in PAH associated with congenital heart disease (APAH-CHD, PAHB n=70, p=0.002; CHC n=29, p=0.007) and was highest in those with a ventricular shunt (n=24, p=0.001). In APAH-CHD, ES was associated with a decreased 6MWD (-108m, -187- -30, p=0.01) and increased mean right atrial pressure (mRAP 1.8mmHg, 0.3-3.3, p=0.02). Longitudinally, in the APAH-CHD subgroup when adjusted for age, sex, and multiple time points, higher ES was associated with increased PVRi and mPAP (PVRi 2.5WU*m 2 , 0.7-4.3, p=0.007; mPAP 10mmHg, 4.5-15, p Conclusions: ES was associated with worse functional measures, pulmonary vascular hemodynamics, and survival in pediatric APAH-CHD. These observations suggest that serum ES could act as a pulmonary vascular specific biomarker to identify those who are at increased risk of developing PAH and predict poor outcomes in APAH-CHD.

Objective: Mutations in both alleles of parkin have been shown to result in Parkinson disease (PD). However, it is unclear whether haploinsufficiency (presence of a mutation in only 1 of the 2 parkin alleles) increases the risk for PD. Methods: We performed comprehensive dosage and sequence analysis of all 12 exons of parkin in a sample of 520 independent patients with familial PD and 263 controls. We evaluated whether presence of a single parkin mutation, either a sequence (point mutation or small insertion/deletion) or dosage (whole exon deletion or duplication) mutation, was found at increased frequency in cases as compared with controls. We then compared the clinical characteristics of cases with 0, 1, or 2 parkin mutations. Results: We identified 55 independent patients with PD with at least 1 parkin mutation and 9 controls with a single sequence mutation. Cases and controls had a similar frequency of single sequence mutations (3.1% vs 3.4%, p = 0.83); however, the cases had a significantly higher rate of dosage mutations (2.6% vs 0%, p = 0.009). Cases with a single dosage mutation were more likely to have an earlier age at onset (50% with onset at ≤45 years) compared with those with no parkin mutations (10%, p = 0.00002); this was not true for cases with only a single sequence mutation (25% with onset at ≤45 years, p = 0.06). Conclusions: Parkin haploinsufficiency, specifically for a dosage mutation rather than a point mutation or small insertion/deletion, is a risk factor for familial PD and may be associated with earlier age at onset.

Objective: A recent study reported that mutations in a gene on chromosome 2q36-37, GIGYF2 , result in Parkinson disease (PD). We have previously reported linkage to this chromosomal region in a sample of multiplex PD families, with the strongest evidence of linkage obtained using the subset of the sample having the strongest family history of disease and meeting the strictest diagnostic criteria. We have tested whether mutations in GIGYF2 may account for the previously observed linkage finding. Methods: We sequenced the GIGYF2 coding region in 96 unrelated patients with PD used in our original study that contributed to the chromosome 2q36-37 linkage signal. Subsequently, we genotyped the entire sample of 566 multiplex PD kindreds as well as 1,447 controls to test whether variants in GIGYF2 are causative or increase susceptibility for PD. Results: We detected three novel variants as well as one of the previously reported seven variants in a total of five multiple PD families; however, there was no consistent evidence that these variants segregated with PD in these families. We also did not find a significant increase in risk for PD among those inheriting variants in GIGYF2 ( p = 0.28). Conclusions: We believe that variation in a gene other than GIGYF2 accounts for the previously reported linkage finding on chromosome 2q36-37. GDS = Geriatric Depression Scale; MMSE = Mini-Mental State Examination; NCRAD = National Cell Repository for Alzheimer’s Disease; PD = Parkinson disease; PSG = Parkinson Study Group; UPDRS = Unified Parkinson’s Disease Rating Scale.

Background: Pathogenic mutations in the leucine-rich repeat kinase 2 gene ( LRRK2 ) have been found to cause typical, later-onset Parkinson disease (PD). Although G2019S is the most common mutation, other mutations have also been reported. It is critical to catalog the types of mutations found in LRRK2 that can cause PD, so as to provide insight regarding disease susceptibility and potential novel treatments. Methods: We performed a comprehensive study of all 51 exons of the LRRK2 gene in one PD patient from each of 88 multiplex PD families who had the highest family-specific multipoint lod score at the LRRK2 locus from a cohort of 430 PD families without the G2019S mutation. Results: Five families (5.7%) harbored what seem to be novel, pathogenic mutations (L1795F, I1192V, E10K, E334K, Q1111H). Three of these apparent mutations were in known, functional domains of the LRRK2 protein, where other studies have also identified disease producing mutations. However, two of the novel variants were found in the N-terminal region of LRRK2, where no pathogenic substitutions have yet been reported. Similar to previous studies, all subjects with an LRRK2 mutation had classic symptoms of PD and typical, later age at onset. Conclusions: We have identified five novel variants in LRRK2, with two of these in the N-terminal region of LRRK2, where no pathogenic substitutions have been previously reported. If confirmed to be causative, these mutations would broaden the potential mechanisms whereby mutations in LRRK2 result in Parkinson disease. GLOSSARY: AD = Alzheimer disease; cDNA = complementary DNA; COR = C terminal of Ras; Hisp = Hispanic; LRR = leucine-rich repeat; LRRK2 = leucine-rich repeat kinase 2 gene; MMSE = Mini-Mental State Examination; NS = nonsynonymous variant that is potentially disease producing; PD = Parkinson disease; Roc = Ras of complex; S = synonymous variant that is not likely to be pathogenic; UPDRS = Unified Parkinson’s Disease Rating Scale.

Background: Spheroid body myopathy (SBM) is a rare, autosomal dominant, neuromuscular disorder, which has only been previously reported in a single large kindred. Identification of the mutated gene in this disorder may provide insight regarding abnormal neuromuscular function. Methods: The authors completed a detailed clinical evaluation on an extensive kindred diagnosed with SBM. Genome-wide linkage analysis was performed to localize the disease gene to a specific chromosomal region. Further marker genotyping and screening of a positional, functional candidate gene were completed to detect the disease-causing mutation. Pathologic analysis of muscle biopsy was performed on three individuals. Biochemical studies were performed on one muscle biopsy specimen from an affected individual. Results: Linkage to chromosome 5q23-5q31 was detected with a lod score of 2.9. Genotyping of additional markers in a larger sample of family members produced a maximum lod score of 6.1 and narrowed the critical interval to 12.2 cM. Screening of the candidate gene titin immunoglobulin domain protein ( TTID , also known as MYOT ) detected a cytosine-to-thymine mutation in exon 2 of all clinically affected family members. Similar pathologic changes were present in all muscle biopsy specimens. Immunohistologic and biochemical analysis revealed that the TTID protein, also known as myotilin, is a component of the insoluble protein aggregate. Conclusions: A novel mutation in the TTID gene results in the clinical and pathologic phenotype termed “spheroid body myopathy.” Mutations in this gene also cause limb-girdle muscular dystrophy 1A and are associated with myofibrillar myopathy.