A gene deletion, or deletion mutation is a genetic mutation in which a part of a chromosome or a sequence of DNA is missing. Any number of nucleotides can be deleted, from a single base to an entire piece of chromosome (Lewis, 2005, p.226). Deletions can be caused by errors in chromosomal crossover during meiosis. Genetics (from the Greek genno γεννώ= give birth) is the science of genes, heredity, and the variation of organisms. ... Mutations are permanent, sometimes transmissible (if the change is to a germ cell) changes to the genetic material (usually DNA or RNA) of a cell. ... Figure 1: Chromosome. ... Space-filling model of a section of DNA molecule Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions specifying the biological development of all cellular forms of life (and many viruses). ... A nucleotide is a monomer or the structural unit of nucleotide chains forming nucleic acids as RNA and DNA. A nucleotide consists of a heterocyclic nucleobase, a pentose sugar (ribose or deoxiribose), and a phosphate or polyphosphate group. ... Chromosomal crossover is the process by which two chromosomes, paired up during Prophase I of meiosis, exchange some distal portion of their DNA. Crossover occurs when two chromosomes, normally two homologous instances of the same chromosome, break and then reconnect but to the different end piece. ... In biology, meiosis is the process that transforms one diploid cell into four haploid cells in eukaryotes. ...

Deletion of a number of base pairs that is not evenly divisible by three will lead to a frameshift mutation, causing all of the codons occurring after the deletion to be read incorrectly during translation, producing a severely altered and potentially nonfunctional protein. Framing error is the following: Generally, a framing error is the result of reading a string of symbols which are grouped in blocks starting at the wrong point. ... RNA codons. ... Translation in the cytoplasm; tRNA carries amino acids which are added to the growing peptide chain in the ribosome. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ...

Deletions are responsible for an array of genetic disorders, including some cases of male infertility and two thirds of cases of Duchenne muscular dystrophy (Lewis, 2005, p.226). A deletion of part of the short arm of chromosome 5 results in cri-du-chat syndrome (Lewis, 2005, p.256). Infertility is the inability to naturally conceive a child or the inability to carry a pregnancy to term. ... The muscular dystrophies are a group of genetic and hereditary muscle diseases; characterized by progressive skeletal muscle weakness, defects in muscle proteins, and the death of muscle cells and tissue. ... 5p- karyotype Cri du chat syndrome, also called deletion 5p syndrome, or 5p minus, is a rare genetic disorder due to a missing portion of chromosome 5. ...

Reference

Lewis R. 2005. Human Genetics: Concepts and Applications, 6th Ed. McGraw Hill, New York.