Golovko ET Al. Literature Reviews Example

Literature Review: Article Components

a) Abstract:
Why? Feline infectious peritonitis (FIP) is caused by a mutated strain of feline corona virus. The disease does not have any treatment, currently and causes mortality close to 100% in cats. Studies in inbred cats found the diseases to be highly heritability. However the gene that renders the feline susceptible to FIP needs to be identified.
What/How? The research seeks to identify evidence for genetic susceptibility to FIP using feline high density single nucleotide polymorphism (SNP) arrays in a genome-wide association study (GWAS) of Birman Cats. 
Major Results: Five candidate genes: ELMO1, RRAGA, TNFSF10, ERAP1 and ERAP, which have relevance in FIP pathogenesis, showed increased association peak with disease susceptibility.
b) Introduction
Importance/Relevance: Intrinsic and extrinsic factors are associated with susceptibility of cats to FIP. Genetic factors are suspected as intrinsic that favor susceptibility of cats to FIP. This is the first study to use genome wide analysis to demonstrate susceptibility to a complex diseases trait in cats.
Prior Research: Pedigree cats are more susceptible to FIP than randomly bred cats. Studies in Persian catteries and pedigree indicate that FIP is 50% heritable.

Current Research Objective: Identify the genes that render susceptibility to FIP in cats.

c) Materials and Methods
Animal Subject: 176 Birman cats were used in the study. This includes 30 cases and 146 controls. The male to female ratio of cats was 1.3: 1.
Phenotyping: The presence and absence of diseases was confirmed by attending veterinarians, based on clinical signs, blood tests, analysis of ascites or pleural fluids, and in some cases by gross or complete necropsies. 

Genotyping/Analysis/Equipment and Software

The DNA isolated from the buccal swabs of the cats was used for SNP analysis.
The alleles identified by this technique were assigned to different regions in the chromosome.
Genome wide analysis studies was performed using PLINK.
Allelic frequency was compared between case and control and the strength of association of a single SNP to diseases susceptibility was expressed as P(raw)
The analysis was done in two parts. In the first part the case and control from all geographical regions were compared.
In the analysis 2, cats in the age of 11/2 years in the case and control were alone compared. This age group had highest degree of diseases incidence.
d) Results
In Analysis 1, the SNP in genes ELMO1, TNFSFIO, RRAGA, showed positive association with diseases susceptibility. ELMO1 has a P (Bonf) of 0.048.
In Analysis 2, the SNP in genes ERAP1, 2, ELMO1, TNFSF10 showed positive association with diseases susceptibility. Four SNP were detected in ERAP1, 2 and all four had a strong association with diseases susceptibility and P (Bonf) <0.05.
e) Discussion
Reminder of Importance: Genetic susceptibility has been implicated in the pathogenesis of FIP. The aim of the study is to identify genes that render genetic susceptibility to FIP in cats.

Interpretations:

A number of SNP associated with the genes TNSF10, ERAP1 & ERAP2, have high confidence in association with diseases.
The candidate gene identified in this study is associated with many immunological pathways like cellular migration, phagocytosis, programmed cell death, virus host interaction.
iii. Future direction: Further studies, in larger sample size can help confirm the association seen in this study. .
iv. Importance and Application: The information can help pedigreed cat breeders when selecting cats for breeding.