chemicals, including 2200 drugs, and connects them to genes and their interactions

from the STRING database.

4.2.4

Genetic Variation and Disease-Gene Interactions

OMIM is the primary repository of curated information on human genetic disease/

disorder phenotypes along with associated gene mutations. The database provides

interactive access to the knowledge repository, including genomic coordinate

searches of the gene map, views of genetic heterogeneity (multiple genes associated

with single diseases), and pleiotropy (Amberger et al. 2019). The database

ORPHANET contains inventory, classification, and encyclopedia of rare diseases

(disease that affects less than 200,000 individuals) and their associated genes and

orphan drugs (Weinreich et al. 2008). The database also offers services to the needs

of patients and their families, health professionals, and researchers. Database of

Single Nucleotide Polymorphism (dbSNP) is a free publicly available resource

(Smigielski et al. 2000) for genetic variation within and across different species

(https://www.ncbi.nlm.nih.gov/snp/). Even though the database contains the major-

ity of the variants as SNPs only, it also contains a range of other molecular

variations: (1) short InDels (insertions and deletions), (2) microsatellite markers or

short tandem repeats, (3).multi-nucleotide polymorphisms, (4) heterozygous

sequences, and (5) named variants. The database also contains genomic and RefSeq

mapping information for both common variations and clinical mutations (Sherry

et al. 2001).

The Human Phenotype Ontology (HPO) provides a systematic vocabulary of

phenotypic abnormalities encountered in human diseases. Each term in the Human

Phenotype Ontology describes a phenotypic abnormality and the Human Phenotype

Ontology identifiers are cross-linked to SNOMED-CT, Orphanet, DECIPHER, and

OMIM identifiers (Köhler et al. 2017). The Phenotype-Genotype Integrator

(PheGenI) database combines NHGRI genome-wide association study (GWAS)

catalog data with several other databases housed NCBI including gene, database

of Genotypes and Phenotypes (dbGaP), Online Mendelian Inheritance in man

(OMIM), dbSNP, and expression quantitative trait loci (eQTL). The database

enables deeper examination of SNPs associated with a variety of traits, facilitating

the identification of the relationships between genetic variations and various diseases

of the human (Ramos et al. 2014). The Genotype-Tissue Expression (GTEx) data-

base is a public resource that consists of tissue-specific gene expression and regula-

tion. It includes whole genome sequencing, whole exome sequencing, and RNA-seq

data from different non-diseased tissue sites across nearly 1000 individuals. It

provides access to data including gene expression, quantitative trait loci, and images

of histology (Lonsdale et al. 2013).

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S. Yellaboina and S. E. Hasnain