Applied neurogenomics

K K Jain MD (Dr. Jain is a consultant in neurology and has no relevant financial relationships to disclose.)
Originally released January 31, 2000; last updated January 20, 2017; expires January 20, 2020

This article includes discussion of applied neurogenomics, the impact of genomics on the practice of neurology, genomes, gel electrophoresis, DNA libraries, microarrays and DNA chips, single nucleotide polymorphisms, copy number variations, DNA sequencing, gene expression in the CNS, proteomics, biomarkers of neurologic disorders, connectomics, brain mapping, systems biology, and neurosciences. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

This article discusses the role of genomics, more specifically neurogenomics, in the neurosciences. Genomic technologies, particularly sequencing, have enabled the study of genes and their relation to neurologic disorders, with an emphasis on diagnosis and treatment. The most significant impact will be development of molecular methods of treatment, integration of diagnostics and therapeutics, and, eventually, development of personalized neurology.

Key points

 

• The advent of the genomic era in the last decade of 20th century has had an impact on the practice of medicine in the earlier part of 21st century (postgenomic era), which is referred to as genomic medicine.

 

• Genomics has an impact on the practice of neurology, particularly for the management of diseases lacking adequate diagnostics and therapeutics.

 

• Genomic neurology will be an important part of personalized neurology.

Historical note and terminology

Genomics is the study of all of the genes in an organism, their sequences, structure, regulation, interaction, and products. As a scientific discipline, genomics involves mapping, sequencing, and analysis of the genomes and can be described as structural or functional. Structural genomics deals with construction of high-resolution genetic, physical, and transcript maps of an organism. The ultimate physical map of an organism is its complete DNA sequence. Functional genomics refers to the development and application of experimental approaches to assess gene function by making use of the information provided by structural genomics. Another related term is “proteomics,” a term that combines the words “protein” and “genome.” The spelling indicates PROTEins expressed by a genOME.

Proteomics is the systematic analysis of protein profiles of tissues and parallels the related field of genomics. The massive amount of information generated by genomics has led to the development of bioinformatics, a discipline based on computerized methods to manage and analyze these data. Landmarks in the historical development of genomics are shown in Table 1.

Table 1. Historical Landmarks in the Development of Genomics

Year

Discovery / Landmark / Reference

Pregenomic era

1871

Discovery of nucleic acids.

1889

Hugo de Vries postulated “Pangene” to be a living, self-replicating unit of heredity. His postulation was adapted from Darwin's “pangenesis” (the process by which cells might produce offspring).

1909

Introduction of the word “gene” (second half of pangene) into the German language as “Gen” by Wilhelm Ludwig Johannsen.

1940

Beadle and Tatum linked genes to unique protein products and formulated the “one gene, one protein” concept.

1951

Discovery of the first protein sequence.

1953

Identification of the double-stranded structure of DNA (Watson and Crick 1953).

1960s

Modern concept of gene expression developed following discovery of messenger RNA, deciphering of genetic code, and description of the theory of genetic regulation of protein synthesis. Establishment of the complete genetic code.

Dawn of the genomic age

1972

Production of the first recombinant DNA organism (Cohen et al 1972).

1975

DNA hybridization analysis (Southern 1975).

1975

Introduction of 2-dimensional electrophoresis of proteins (O'Farrell 1975).

1977

Advent of DNA sequencing.

1978

Discovery of restriction fragme

1981

Gene mapping by in situ hybridization becomes a standard method.

1982

GenBank is established.

1983

Demonstration of Huntington disease gene (Gusella et al 1983).

1985

Discovery of polymerase chain reaction (Mullis et al 1986).

1986

Dr. Roderick coined the word "genomics" as the title of the journal that started publication in 1987 (Kuska 1998).

1987

Identification of dystrophin, the protein product of Duchenne muscular dystrophy gene, which now forms basis of gene therapy for this disorder (Hoffman et al 1987).

Genomic age

1990

Launch of the Human Genome Project, National Institutes of Health, United States (a billion/15-year project).

1990

First human gene therapy experiment. Correction of adenosine deaminase deficiency in T-lymphocytes using retroviral-mediated gene transfer (Blaese et al 1990).

1991

Venter found that expressed sequence tags can provide a cheap, rapid way to skim the genome for practical information. Starting point of commercialization of genomics.

1995

Definition of the proteome (Wilkins et al 1996).

1996

Completion of the first whole genome sequence of an organism: the budding yeast Saccharomyces cerevisiae.

1999

First human chromosome sequenced: chromosome 22.

2000

Completion of the sequencing of the human genome ahead of the anticipated date.

Postgenomic Era

 

2000-2010

Increase in amount of sequence data; integration of information from genomics with that from other -omics, such as proteomics and metabolomics; and applications for the development of personalized medicine.

Genomic neurology can be defined as the application of genomics to neurology and is considered to be a part of molecular neurology. Neurogenomics is the study of genes in the nervous system. Of particular interest in neurology are the genes involved in neurologic disorders. In a broad sense, neurogenomics is the study of how the genome as a whole contributes to the evolution, development, structure, and function of the nervous system. The closely related term “neurogenetics” deals with the role of genetics in development and function of the nervous system as well as investigation and management of genetic disorders of the nervous system.

Neurology made considerable progress during the last decade of the twentieth century (Decade of the Brain) with advances in therapeutics of previously untreatable diseases. This was also the genomic decade, and the developments in genomic technologies have revolutionized the practice of medicine during the postgenomic era. Neurologists are expected to keep up-to-date with advances in neurogenomics, which is related to other “omics.”

Image: Relationships of neurogenomics with other omics

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