Department of Human Genetics

Why are these studies being done?

The purpose of these studies is to determine how often otherwise unexplained developmental disabilities, congenital disabilities, and/or pregnancy losses are due to subtle (or very small) chromosome abnormalities. Individuals with a developmental disability may have learning difficulties, mental retardation, behavioral problems (such as autism), or other characteristics. Individuals with birth defects may have a heart defect, cleft lip, cleft palate, spina bifida (hole in the spine) as well as other defects.

If a person has a whole chromosome or part of a chromosome missing or extra, there may be developmental disabilities, birth defects, and/or pregnancy loss. People with all or part of a chromosome missing or extra are said to have UNBALANCED chromosome abnormalities. Some healthy people have a rearrangement of their chromosomes called a BALANCED translocation. If a person has a balanced translocation, he/she may have a higher than average risk of having pregnancy losses or a child with developmental disabilities or birth defects because their offspring can inherit UNBALANCED chromosome abnormalities. Sometimes babies are born with balanced or unbalanced chromosome abnormalities even though their parents do not have a chromosome abnormality; these are called de novo (or new) abnormalities.

In this study, we are looking for unbalanced chromosome abnormalities and balanced chromosome rearrangements, which involve small pieces of chromosomes. These chromosome abnormalities may not be found by using our current testing methods. Therefore, for this study, we are using a new test methodologies to find subtle chromosome abnormalities.

The following sub-study is included in this research.

Genotype/Phenotype Database

A genotype/phenotype database for individuals with an unbalanced telomere or centromere abnormality is under development. No personal identifiers will be included in the database. Therefore, the database will be available via the web for use by professionals and families.