Genetics in an orthodontic perspective

Genetics is the science concerned with the structure and function of all genes in different organisms. Malocclusion is a manifestation of genetic and environmental interaction on the development of the orofacial region. It is important to consider genetic factors to understand the cause of existing problems, which has influence the outcome of treatment. The review aims to provide information to the dental practitioner and orthodontist on basics of genetics and common disorders with gene impairments. These genetic factors in turn have an impact on outcome of orthodontic treatment. Introduction to Basics of Genetics Growth is the combined result of interaction between several genetic and environmental factors overtime.[1] Malocclusion is a manifestation of genetic and environmental interaction on the development of the orofacial region. It is important to consider genetic factors to understand the cause of existing problems, which influences the outcome of treatment.[2] Genetics is the science concerned with the structure and function of all genes. Austrian monk, Gregor John Mendel was known as “father of modern genetics.” The studies by Mendel, on garden pea, he put forward basic laws of genetics, namely law of segregation, law of independent assortment, and law of dominance. In 1903, Sulton and Boveri proposed the “Chromosomal Theory of Inheritance.”[2] Thomas Hunt Morgan studied the arrangement of genes along chromosomes. In 1953, Watson and Crick demonstrated the structure of DNA molecule. Solenoid model of chromosome was proposed by Finch and Klung.[2,3] The cell is the basic unit of any living body. It is made of organelles such as cell wall cytoplasm, endoplasmic reticulum, ribosomes, mitochondria, and nucleus. The nucleus has threadlike structures of different length and shapes called chromosomes. The number of chromosomes in every cell of an organism is constant, and it changes from one species to another. All humans normally have 23 pairs of chromosomes as 22 pairs of autosomes and one pair of sex chromosomes. Females have two X chromosomes, while male has one Xand one Y-chromosome. Gene is the smallest structural and functional unit of inheritance. Segment contains information required for the synthesis of a polypeptide. Genes have the ability to determine traits and undergo identical replication and mutation. Genome is the entire genetic content of a set of chromosomes present within a cell or organism. The genome varies from one individual to another in terms of single base changes of DNA as single-nucleotide polymorphisms (SNPs). The main use of human SNP map will be to determine the contribution of genes to diseases. Transcription is the process by which information is transmitted from DNA to the messenger RNA at the initial stages of replication and translation is the process in which the genetic information is actually converted into proteins. Transcription