The study of obesity has drawn wide-spread interest because of its far-reaching consequences. Obesity is on the rise and has been linked to several clinical complications such as type 2 diabetes and hypertension. Obesity is defined as a condition in which body mass index (BMI) is greater than 3m2/kg. BMI itself is highly heritable with the rate of heritability in twin and adoption studies ranging from 45%–85%.
The study was designed to analyze the differences in gene expression in MZ twin pairs discordant for BMI. A total of 26 twin pairs were selected based on a within-pair BMI difference of more than 3 kg/m2 when compared to his or her twin. The twins for this study belonged to either FinnTwin16 (birth cohort 1975-1979) or FinnTwin12 (birth cohort 1983-1987).
Samples were extracted from the participants and used in microarray experiments. The resulting data was processed using various packages of the Bioconductor software. The quality control process identified one sample as faulty and as a result the sample as well as the sample of the twin were discarded. This resulted in a sample size of 50 twins. Differential analysis carried out using the limma package of Bioconductor revealed 980 genes that were differentially expressed. These genes were then processed further in the Ingenuity Pathway Analysis (IPA) tool as well as the BiNGO tool. This revealed the molecular networks, gene pathways and gene annotations that were pertinent to the genes uploaded. IPA also provided a list of functions and diseases these genes were involved in. As the final step, the prevalent themes across these results were summarized.
This analysis provided many leads that should be investigated further in future studies. It is suggested that future studies start with precise, concrete biological questions that narrow down the scope of biological analysis. This is in view of the extensive amount of data available via microarray studies and the myriad of hypothesizes that can be investigated.
