Johanna K DiStefano

Dr. Johanna K DiStefano

Translational Genomics Research Institute, Phoenix, Arizona, USA
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Research Focus & Metrics

Academic Career Length

33Years (1994-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 November 2012 in Kidney International
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Journal Article
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MAM. Lucrecia Alvarez
M. Lucrecia Alvarez
MKMahdieh Khosroheidari
Mahdieh Khosroheidari
RRRupesh Kanchi Ravi
Rupesh Kanchi Ravi
Johanna K DiStefanoJohanna K DiStefano
Johanna K DiStefano

11 August 2020 in Endocrinology
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Journal Article
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Johanna K DiStefanoJohanna K DiStefano
Johanna K DiStefano
Nonalcoholic fatty liver disease (NAFLD) prevalence in women is increasing worldwide. Women of reproductive age have lower rates of NAFLD compared with men; however, this protection is lost following the menopausal transition when NAFLD prevalence in postmenopausal women becomes similar to or surpasses that in age-matched male counterparts. Ongoing epidemiological, clinical, and experimental studies indicate greater NAFLD risk and higher rates of severe hepatic fibrosis in postmenopausal women relative to premenopausal women, and that older women with NAFLD experience greater mortality than men. Investigations involving ovariectomized animal models demonstrate a causal relationship between estrogen deficiency and heightened susceptibility to the development of fatty liver and steatohepatitis, although dietary factors may exacerbate this complex relationship. The accumulated findings suggest that a better understanding of the interplay among menopausal status, metabolic comorbidities, and sex steroids in NAFLD pathogenesis is needed. Further, the mechanisms underlying the difference in NAFLD risk between postmenopausal and premenopausal women remain incompletely understood. The goals of this review are to summarize studies of NAFLD risk in postmenopausal women, discuss results from animal models of estrogen deficiency, and explore the development of NAFD within the context of altered sex hormone profiles resulting from the menopausal transition. Potential implications for the prevention, diagnosis, and treatment of NAFLD in this relatively understudied cohort are also addressed.


1 April 2007 in Diabetes
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RHRobert L. Hanson
Robert L. Hanson
DCDavid W. Craig
David W. Craig
MMMeredith P. Millis
Meredith P. Millis
KYKimberly A. Yeatts
Kimberly A. Yeatts
SKSayuko Kobes
Sayuko Kobes
Johanna K DiStefanoJohanna K DiStefano
Johanna K DiStefano
To identify genetic variants contributing to end-stage renal disease (ESRD) in type 2 diabetes, we performed a genome-wide analysis of 115,352 single nucleotide polymorphisms (SNPs) in pools of 105 unrelated case subjects with ESRD and 102 unrelated control subjects who have had type 2 diabetes for ≥10 years without macroalbuminuria. Using a sliding window statistic of ranked SNPs, we identified a 200-kb region on 8q24 harboring three SNPs showing substantial differences in allelic frequency between case and control pools. These SNPs were genotyped in individuals comprising each pool, and strong evidence for association was found with rs2720709 (P = 0.000021; odds ratio 2.57 [95% CI 1.66–3.96]), which is located in the plasmacytoma variant translocation gene PVT1. We sequenced all exons, exon-intron boundaries, and the promoter of PVT1 and identified 47 variants, 11 of which represented nonredundant markers with minor allele frequency ≥0.05. We subsequently genotyped these 11 variants and an additional 87 SNPs identified through public databases in 319-kb flanking rs2720709 (∼1 SNP/3.5 kb); 23 markers were associated with ESRD at P < 0.01. The strongest evidence for association was found for rs2648875 (P = 0.0000018; 2.97 [1.90–4.65]), which maps to intron 8 of PVT1. Together, these results suggest that PVT1 may contribute to ESRD susceptibility in diabetes.

1 January 2021 in Journal of Hepatology
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KTKevin Teo
Kevin Teo
KAKushala W.M. Abeysekera
Kushala W.M. Abeysekera
LALeon Adams
Leon Adams
EAElmar Aigner
Elmar Aigner
QAQuentin M. Anstee
Quentin M. Anstee
JMJake P. Mann
Jake P. Mann
A common genetic variant near MBOAT7 (rs641738C>T) has been previously associated with hepatic fat and advanced histology in NAFLD; however, these findings have not been consistently replicated in the literature. We aimed to establish whether rs641738C>T is a risk factor across the spectrum of NAFLD and to characterise its role in the regulation of related metabolic phenotypes through a meta-analysis. We performed a meta-analysis of studies with data on the association between rs641738C>T genotype and liver fat, NAFLD histology, and serum alanine aminotransferase (ALT), lipids or insulin. These included directly genotyped studies and population-level data from genome-wide association studies (GWAS). We performed a random effects meta-analysis using recessive, additive and dominant genetic models. Data from 1,066,175 participants (9,688 with liver biopsies) across 42 studies were included in the meta-analysis. rs641738C>T was associated with higher liver fat on CT/MRI (+0.03 standard deviations [95% CI 0.02–0.05], pz = 4.8×10–5) and diagnosis of NAFLD (odds ratio [OR] 1.17 [95% CI 1.05–1.3], pz = 0.003) in Caucasian adults. The variant was also positively associated with presence of advanced fibrosis (OR 1.22 [95% CI 1.03–1.45], pz = 0.021) in Caucasian adults using a recessive model of inheritance (CC + CT vs. TT). Meta-analysis of data from previous GWAS found the variant to be associated with higher ALT (pz = 0.002) and lower serum triglycerides (pz = 1.5×10–4). rs641738C>T was not associated with fasting insulin and no effect was observed in children with NAFLD. Our study validates rs641738C>T near MBOAT7 as a risk factor for the presence and severity of NAFLD in individuals of European descent. Fatty liver disease is a common condition where fat builds up in the liver, which can cause liver inflammation and scarring (including ‘cirrhosis’). It is closely linked to obesity and diabetes, but some genes are also thought to be important. We did this study to see whether one specific change (‘variant’) in one gene (‘MBOAT7’) was linked to fatty liver disease. We took data from over 40 published studies and found that this variant near MBOAT7 is linked to more severe fatty liver disease. This means that drugs designed to work on MBOAT7 could be useful for treating fatty liver disease.

22 April 2011 in PLOS ONE
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MAM. Lucrecia Alvarez
M. Lucrecia Alvarez
Johanna K DiStefanoJohanna K DiStefano
Johanna K DiStefano
We previously observed association between variants in the plasmacytoma variant translocation 1 gene (PVT1) and end-stage renal disease (ESRD) attributed to both type 1 and type 2 diabetes, and demonstrated PVT1 expression in a variety of renal cell types. While these findings suggest a role for PVT1 in the development of ESRD, potential mechanisms for involvement remain unknown. The goal of this study was to identify possible molecular mechanisms by which PVT1 may contribute to the development and progression of diabetic kidney disease. We knocked-down PVT1 expression in mesangial cells using RNA interference, and analyzed RNA and protein levels of fibronectin 1 (FN1), collagen, type IV, alpha 1 (COL4A1), transforming growth factor beta 1 (TGFB1) and plasminogen activator inhibitor-1 (SERPINE1 or PAI-1) by qPCR and ELISA, respectively. PVT1 expression was significantly upregulated by glucose treatment in human mesangial cells, as were levels of FN1, COL4A1, TGFB1, and PAI-1. Importantly, PVT1 knockdown significantly reduced mRNA and protein levels of the major ECM proteins, FN1 and COL4A1, and two key regulators of ECM proteins, TGFB1 and PAI-1. However, we observed a higher and more rapid reduction in levels of secreted FN1, COL4A1, and PAI-1 compared with TGFB1, suggesting that at least some of the PVT1 effects on ECM proteins may be independent of this cytokine. These results indicate that PVT1 may mediate the development and progression of diabetic nephropathy through mechanisms involving ECM accumulation.