Genetic Disorders and Conditions

Blood Disorders

Genetic blood disorders result from defects in a necessary protein called hemoglobin. Hemoglobin is a substance in red blood cells that is responsible for carrying oxygen to all parts of the body. These disorders, also called hemoglobinopathies, change the shape of blood cells, causing them to function improperly. The most common hemoglobinopathies are Sickle Cell Anemia and Thalassemia.

Sickle Cell Anemia

This disease causes red blood cells to clump up. This can clog vessels and create severe pain. The body naturally destroys these deformed cells. This results in a low blood cell count, which causes the body to lose its ability to function efficiently (anemia). This can lead to fatigue, infection and even death. It is more common in persons of African-American, Hispanic, Middle Eastern, and Asian descent.  

  • DSHS Sickle Cell Homepage links you to other sites relating to this disease and provides publications in both Spanish and English.
  • Parent’s Guide advises you what to do if you have a school-aged child with this disease.  

Metabolic Disorders

Metabolic disorders are genetic diseases that affect the body’s ability to perform its normal chemical reactions. Defective enzymes or other molecules that are needed cause either a buildup of harmful substances or lack of required substances. The result of this disease can lead to intellectual disability or can cause organs to function improperly. Phenylketonuria (PKU) and Galactosemia are common examples of metabolic disorders.  

Phenylketonuria (PKU)

This disorder results from the harmful buildup of an amino acid called phenylalanine. This amino acid is part of many of the proteins that we eat. When the body breaks down those proteins it gets rid excess amino acids. Your body needs a special enzyme to get rid of the extra phenylalanine. This enzyme is defective in people with PKU, which causes too much to buildup. This can lead to intellectual disability if left untreated. 


This disorder deals with the digestion of sugar. One type of sugar the body uses is lactose. It is the primary sugar found in milk and dairy products. When the body breaks down this sugar, it is split into two substances: glucose and galactose. The body then uses enzymes to convert these substances into energy. In galactosemia, the enzyme needed to use galactose is defective, resulting in a buildup of galactose. This can lead to brain damage, digestive problems and deadly infections.

The State of Texas currently tests for PKU and Galactosemia through the Newborn Screening Program. Supplemental Newborn Screening can detect more than 30 disorders of body chemistry in a single analysis of a small blood sample that is collected on a special paper during the first few days of life. For more information about supplemental newborn screening contact the National Newborn Screening and Genetics Resource Center

Endocrine Disorders

Endocrine disorders affect the glands of the endocrine system. The endocrine system is responsible for producing hormone messengers that allow different parts of the body to communicate with each other. Two examples of genetic endocrine disorders are Congenital Adrenal Hyperplasia (CAH) and Congenital Hypothyroidism

Congenital Adrenal Hyperplasia (CAH)

CAH is an inherited condition that is present at birth. In CAH the adrenal glands do not produce enough of the right amount of hormones that are needed for our bodies to function normally. The adrenal glands are a pair of small organs, each about the size of a walnut. They are located on top of each of the kidneys just below the ribs in the back. They produce three hormones, or chemical messengers called cortisol (hydrocortisone), aldosterone (salt- retaining hormone), and androgens (male sex hormones). CAH occurs when the adrenal glands do not produce enough cortisol and aldosterone hormones, and instead produce too much of the male-like hormones, androgens. 

Congenital Hypothyroidism

Congenital hypothyroidism is a condition in which the thyroid gland does not produce enough thyroid hormone to meet the needs of the body. The treatment is daily replacement of the missing thyroid hormone with synthetic thyroid hormone tablets (also called sodium levothyroxine or L-thyroxine). The synthetic thyroid hormone acts exactly like the hormone produced by the thyroid gland.

Other Disorders

There are many other known genetic disorders. Everyday, scientists work to discover new genes and the characteristics that they code for. 

  • Birth Defects and Epidemiology Surveillance - This area of the Texas Department of State Health Services seeks to learn more about the causes of birth defects, in working toward prevention and linking families with services that help meet their needs.
  • March of Dimes - The mission of the March of Dimes is to improve the health of babies by preventing birth defects and infant mortality.
  • National Organization for Rare Disorders, Inc. - NORD is a unique federation of voluntary health organizations dedicated to helping people with rare "orphan" diseases and assisting the organizations that serve them. NORD is committed to the identification, treatment, and cure of rare disorders through programs of education, advocacy, research, and service.
  • Glossary of Genetic Terms - Provides explanations of the terminology used when talking about genetics and genetic disorders.

External links to other sites are intended to be informational and do not have the endorsement of the Texas Department of State Health Services. These sites may also not be accessible to persons with disabilities.