VATER association Health Article

Definition

VATER association describes a pattern of related birth defects in the same infant involving three or more of the following: vertebrae (spine), anus and rectum, heart, trachea (windpipe), esophagus, radius (bone of the arm), and kidneys. Infants can have any combination of features and there is a wide range of severity. Survival and medical complications depend on the extent and severity of features in each case.

Description

Quan and Smith first developed the term VATER association in 1973 to describe a similar pattern of birth defects in more than one infant. The problems at birth did not represent a certain syndrome but appeared to be associated since they were present in several babies. VATER is an acronym or abbreviation representing the first letter of each feature in the association: Vertebral (spine) abnormalities, Anal atresia (partial absence of the anus or unusual connection between anus and rectum), Tracheo Esophageal fistula (connection between the windpipe and the tube carrying food from mouth to stomach), and Radial (bone of the forearm) or Renal (kidney) differences.

In the 1970s some researchers expanded the VATER abbreviation to VACTERL. It was expanded to include cardiac (heart) abnormalities, and limb differences in general (differences in the arms and hands). In the expanded VACTERL, "L" includes radial differences and "R" represents kidney differences only. Both VATER and VACTERL are used to describe the same association of birth defects.

The exact cause of VATER is unknown. This is because VATER is rare and because the features vary from patient to patient. Many researchers agree that the cause of VATER occurs very early in the development of the embryo in order to affect so many organ systems. It is unknown whether VATER has a single cause or multiple causes during this early development process.

In the first couple of weeks after conception, a human embryo is a clump of cells that are unspecialized and full of potential. In the third week of pregnancy the embryo undergoes a process called gastrulation. This is when the cells of the embryo begin to group together in different areas. The different cell groups begin to specialize and prepare to form different organs and body parts. The mesoderm is the group of cells that organizes and eventually forms the baby's bones, muscles, heart, blood, kidneys, and reproductive organs. In the third week of pregnancy, the notochord also develops. The notochord is the future spinal cord and gives the early embryo a center and stability. It may also have a role in organizing other cell groups. The primitive gut also organizes in the fourth week. The primitive gut undergoes more specialization and division into zones called the foregut, midgut, and hindgut. The esophagus (tube from mouth to stomach) and trachea (windpipe) develop from the foregut. The anus and rectum develop from the hindgut. The constant cell movement, grouping, and specialization is a precise process. Any interruption or damage in this early stage can affect multiple organs and body structures.

Some researchers believe the cause of VATER is a problem with gastrulation. Other researchers believe the error occurs when mesoderm cells begin to move to areas to begin specialization. Another theory is that the mesoderm receives abnormal signals and becomes disorganized. Other researchers believe more than one error occurs in more than one area of the early embryo to produce VATER. Some also believe an abnormality of the notochord is involved in the development of VATER.

One group of researchers has discovered that pregnant rats that are given a toxic drug called adriamycin have offspring with birth defects very similar to those seen in humans with VATER. This has allowed the researchers to study normal and abnormal development of the early embryo. The study of rats showed abnormal notochord development in offspring with connections of the trachea and esophagus. In those offspring, the notochord was thickened and connected unusually to the foregut. More research of this animal model will answer many questions about the development and cause of the features of VATER.