At conception, “we all start out the same.” Disorders (or differences) of Sex Development (DSD) is an umbrella term for the differences in the typical path of sex development from conception to birth. These different paths may be influenced by the arrangement of sex chromosomes, the functioning of the gonads (i.e. testes, ovaries), and our bodies’ response to hormones. DSD can occur in both boys and girls and are organized into three main categories based on the person’s sex chromosomes:
- Sex Chromosome DSD
- 46,XY DSD
- 46,XX DSD
People are typically born with 46 chromosomes in each cell. Chromosomes are threadlike structures of tightly packaged DNA and are usually found in an arrangement of 23 pairs. One pair of chromosomes, the sex chromosomes, helps determine whether a person will develop male or female physical sex characteristics. There are two types of sex chromosomes, X and Y. Females usually have two X chromosomes and are labeled as (46,XX) and males usually have one X and one Y chromosome (46,XY).
Sex Chromosome DSD
These DSD include any condition in which there is atypical arrangement of the sex chromosomes. For example, Turner syndrome or (45,X) is a condition that occurs when a child is born with only 45 chromosomes because one of the sex chromosomes is missing. For some people, the cells of their body include more than one type of sex chromosome arrangement. For example, some cells may have one X and Y chromosome and other cells include a single X chromosome (45,X/46,XY). The mixture of cells is referred to as mosaicism.
Children that are born with one X chromosome and Y chromosome (46,XY) usually develop male sex characteristics. However, some children born with one X and Y chromosome have underdeveloped gonads or cannot produce or respond to sex hormones to develop the typical male physical characteristics. Instead they may develop genital appearance that appears more feminine or atypical.
Children that are born with two X chromosomes (46,XX) usually develop female physical sex characteristics. However, some children born with two X chromosomes were exposed before birth to excess male sex hormones that led to genitals that appear atypical.
Members of the University of Michigan DSD team at C.S. Mott Children’s Hospital understand that each child with a DSD is unique, and that each family has different concerns and needs. Our mission is to partner with our patients and their families to provide comprehensive, coordinated care that meets long-term physical, social and emotional needs.
Take the next step:
To learn more about the Disorders of Sex Development program at C.S. Mott Children’s Hospital, or to schedule an appointment, call 734-232-0436.