(See also Overview of Chromosome Disorders Overview of Chromosome and Gene Disorders Chromosomes are structures within cells that contain a person's genes. A gene is a segment of deoxyribonucleic acid ( DNA) and contains the code for a specific protein that functions in one... read more .)
Chromosomes Chromosomes Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body or the code for functional ribonucleic... read more 
are structures within cells that contain DNA DNA Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body or the code for functional ribonucleic... read more and many genes.
A gene is a segment of deoxyribonucleic acid (DNA) and contains the code for a specific protein that functions in one or more types of cells in the body ( see Genes and Chromosomes Genes and Chromosomes Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body or the code for functional ribonucleic... read more for a discussion about genetics). Genes contain instructions that determine how the body is supposed to look and function.
When parts of chromosomes are missing, a number of syndromes can occur. These syndromes are called chromosomal deletion syndromes. They tend to cause birth defects and limited intellectual development Intellectual Disability Intellectual disability is significantly below average intellectual functioning present from birth or early infancy, causing limitations in the ability to conduct normal activities of daily... read more and physical development. In some cases, defects can be severe and affected children may die during infancy or childhood.
There are many chromosomal deletion syndromes, which include
Chromosomal deletions can be suspected before or after birth and confirmed by chromosomal testing. (See also Next-generation sequencing technologies Next-generation sequencing technologies Genetic diagnostic technologies are scientific methods that are used to understand and evaluate an organism's genes. (See also Genes and Chromosomes.) Genes are segments of deoxyribonucleic... read more .)
Some physical defects can be corrected with surgery, but generally treatment is supportive.
