MO383: Structural Equation Modelling to Improve Kidney Function Assessment in The General Population

BACKGROUND AND AIMS

In order to identify behavioral, environmental, biological or genetic determinants of kidney function, population-based epidemiological studies rely on approximate estimates of the glomerular filtration rate (eGFR) based on measured markers such as serum creatinine, cystatin C, and a few other [1,2]. Since none of these markers is the exclusive reflection of the kidney function, results should always be interpreted with caution to disentangle determinants of kidney function from those that are specific to the marker metabolism. A structural equation modelling (SEM) approach could overcome these limitations allowing to estimate the unobservable kidney function based on a larger number of markers, improving the possibilities of conducting more specific inferential studies [3]. We implemented SEM to identify a latent kidney function trait in a general population sample and validated this derived biomarker against 10-year incidence of kidney disease using an independent dataset.

METHOD

In the population-based MICROS study (South Tyrol, Italy) [4], we measured serum creatinine (SCr), uric acid (UA), blood urea nitrogen (BUN), cystatin C (CysC), and serum albumin in 1317 study participants. We split the sample into a model-building (n = 647) and a validation set (n = 670). The model-building set was used for SEM analysis and estimation of factor loadings for each biomarker, using the R package ‘lavaan’. Participants in the validation set were submitted a 10-year follow-up interview on kidney disease within the Cooperative Health Research In South Tyrol (CHRIS) study [5]. We fitted logistic regression models to assess the predictivity of the estimated latent kidney function trait versus each individual marker, CKD-EPI eGFR estimates based on serum creatinine and cystatin C (CKD-EPI 2009; CKD-EPI 2021; CKD-EPI Cys; and CKD-EPI CreCys), as well as MDRD-4 and MDRD-6. We estimated odds ratios (ORs) for 10-year kidney disease incidence per standard deviation (SD) change in each marker.

RESULTS

In the model-building set (mean age 49 years, SD = 19; 58% females; mean eGFRCKD-EPI 2021 = 85.9, SD = 20.9), we identified factor loadings for SCr, UA, BUN, and CysC (Figure 1) achieving acceptable goodness of fit (Chi-square = 14.7; CFI = 0.98; TLI = 0.93; and RMSEA = 0.099). The validation set (baseline mean age = 40 years, SD = 13; 55% females; mean eGFRCKD-EPI 2021 = 100.8, SD = 16.1) had a 10-year kidney disease incidence of 7.8%. For the latent kidney function trait, we observed an OR of 2.1 (95% CI: 1.4–3.2) for incidence per each SD change. This was lower than the ORs (95% CI) associated with the eGFRMDRD4 (2.3, 1.4–4.1) and eGFRMDRD6 (2.5, 1.5–4.2), but larger than the ORs (95% CI) observed for all other markers (SCr: 1.8, 1.3–2.6; UA: 1.2, 0.9–1.8; BUN: 1.3, 0.9–1.8; and CysC: 1.3, 1.0–1.7) or eGFR estimates (eGFRCKD-EPI2009: 1.8, 1.2–2.7; eGFRCKD-EPI2021: 1.7, 1.2–2.5; eGFRCKD-EPI Cys: 1.4, 1.0–1.9; and eGFRCKD-EPI CreCys: 1.8, 1.2–2.6).

CONCLUSION

A latent kidney function trait derived from SEM performed similarly and often better than conventional eGFR estimates in a 10-year kidney disease incidence prediction. The method warrants validation in independent general population samples with large sample size.

Prediction of Genes Involved in Lung Cancer with a Systems Biology Approach Based on Comprehensive Gene Information

Over the past few years, hundreds of genes have been reported in relation to lung cancer. Systems biology studies can help validate this association and find the most valid genes to use in the diagnosis and treatment. We reviewed the candidate genes for lung cancer in 120 published articles from September 1, 1993, to September 1, 2020. We obtained 134 up- and 36 downregulated genes for lung cancer in this article. The genes extracted from the articles were imported to Search Tool for the Retrieval of Interacting genes/proteins (STRING) to construct the protein-protein interaction (PPI) Network and pathway enrichment. GO ontology and Reactome databases were used for describing the genes, average length of survival, and constructing networks. Then, the ClusterONE plugin of Cytoscape software was used to analyze and cluster networks. Hubs and bottleneck nodes were defined based on their degree and betweenness. Common genes between the ClusterONE plugin and network analysis consisted of seven genes (BRCA1-TP53-CASP3-PLK1-VEGFA-MDM2-CCNB1 and PLK1), and two genes (PLK1 and TYMS) were selected as survival factors. Our drug-gene network showed that CASP3, BRCA1, TP53, VEGFA, and MDM2 are common genes that are involved in this network. Also, among the drugs recognized in the drug-gene network, five drugs such as paclitaxel, oxaliplatin, carboplatin, irinotecan, and cisplatin were examined in different studies. It seems that these seven genes, with further studies and confirmatory tests, could be potential markers for lung cancer, especially PLK1 that has a significant effect on the survival of patients. We provide the novel genes into the pathogenesis of lung cancer, and we introduced new potential biomarkers for this malignancy.

ASSOCIATION OF FOXP3 GENE VARIANTS WITH RISK OF HASHIMOTO'S THYROIDITIS AND CORRELATION WITH ANTI-TPO ANTIBODY LEVELS

CONTEXT

Regulatory T cells (Tregs) have critical roles in preventing autoimmune diseases such as Hashimoto's thyroiditis (HT). Forkhead box P3 (Foxp3), the master transcription factor of Tregs, plays a pivotal role in Treg function.

OBJECTIVE

Herein, we investigated the association of two single nucleotide polymorphisms (SNPs) of the Foxp3 gene with HT development.

METHODS AND STUDY DESIGN

A total of 129 HT patients and 127 healthy subjects were genotyped for rs3761548 (-3279 A/C) and rs3761549 (-2383 C/T) in the Foxp3 gene, using polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

Genotypic and allelic distribution of rs3761548 SNP showed a significant association with HT. The CC genotype was observed in 37.2% of patients versus 22.1% of the controls [P<0.008, odds ratio (OR): 2.1; 95% confidence interval (CI): 1.2-3.6] and the AC genotype in 41.1% of patients compared to 54.3% of the controls (P<0.025, OR: 2.1; CI: 1.2-3.6). In addition, higher frequency of C allele in patients compared to controls (P=0.05, OR: 1.4; 95% CI: 0.9-2) suggested that patients with the CC genotype and C allele had increased susceptibility to HT. There were significantly higher serum levels of anti-thyroid peroxidase (ATPO) antibody in patients with the rs3761548 CC genotype (1156±163 IU/mL) compared to the other genotypes (≈582-656 IU/mL; P<0.004). We observed a greater frequency of the AC genotype in patients who had decreased ATPO antibody levels (P=0.02).

CONCLUSIONS

The association of the rs3761548 SNP with risk of HT and its influence on ATPO antibody levels suggested an important role for Foxp3 in the biology and pathogenesis of HT.

Knowledge and attitude toward genetic diseases and genetic tests among pre-marriage individuals: A cross-sectional study in northern Iran

Background

Genetic testing has been widely introduced for many hereditary disorders. While the attitudes towards these facilities have been evaluated in many countries, there are only a few reports on the knowledge of and the orientation among Iranians.

Objective

The current study assesses the attitudes and knowledge of pre-marriage individuals toward the availability and use of genetic tests.

Materials and Methods

A comprehensive questionnaire was distributed among 408 marrying individuals. The questions addressed the demographic characteristics along the registration of participant's knowledge, education, and attitude toward genetic testing. The individuals were divided into three groups based on their knowledge: 1) Scored above 80 to 100 were defined as "good" 2) 60 to 80 as "average" 3) less than 60 as "poor" knowledge.

Results

Most participants (86%) believed consanguineous marriages increase the risk of genetic diseases; 82.3% knew that thalassemia is a type of genetic disease, only 33.3% could distinguish prenatal diagnosis (PND) from other laboratory tests. The relationship between the participants' knowledge and their level of education was significant (r░=░0.78, p░<░0.001), age (r= -0.16, p░<░0.01), and urbanity (p░<░0.01). A prominent relationship was observed between the knowledge (r░=░0.64, p░<░0.001) or education (r░=░0.62, p░<░0.001) and people’s desire to use the genetic tests before the wedding ceremony. No significant correlations were found between the participant’s attitude and their ages/urbanity. Most of the individuals agreed to arrange a genetic counseling before marriage (0.94%).

Conclusion

This study revealed that most individuals were interested in using genetic counseling services and genetic tests before marriage.