The term haploinsufficiency describes microdeletion. In simple terms, haploinsufficiency means insufficiency of a single copy of a normal gene for producing protein, thereby affecting the function. Two situations arise in the case of haploinsufficiency. An individual, heterozygous for the gene mutation gets affected with deletion or microdeletion for a gene segment, a gene or a corresponding allele. Other situation arises when the individual is hemizygous for a particular locus. Deletion syndromes arise due to copy number losses. Submicroscopic differences (losses) in few sections of the DNA result into copy number variations. Microdeletions involve two types such as a terminal or interstitial deletions. Independent of a location of a gene, microdeletions occur anywhere such as Centromeric regions, telomeric regions or any other regions of the chromosomes. The deletions in the interstitial regions involve the regions between the centromere and the site of rearrangement. The microdeletions involving the chromosomal ends are known as terminal microdeletions. The inheritance of microdeletion syndromes follows autosomal or sex-linked inheritance. Few references site novel cases of telomeric microdeletions.