What is congenital athymia?

Congenital athymia is a rare immune condition that requires children and often their families to live in strict isolation

Congenital athymia is a primary immunodeficiency, which is a type of immune condition that occurs when part of the immune system is missing. Children with congenital athymia are born without a functioning thymus.

The thymus is an organ that sits on top of the heart and plays an important role in how the immune system works. Without a functioning thymus, these children can face life-threatening infections because they are unable to produce enough naive T cells—white blood cells that help fight off the organisms that cause infections.

Approximately 17 to 24 infants are born with congenital athymia in the US each year.

Diagram of the thymus' function

Complete DiGeorge Syndrome

Complete DiGeorge syndrome often occurs when part of chromosome 22 is missing (22q11.2 deletion syndrome). This may result in a compromised immune system as well as potential heart defects, developmental delay, and hearing loss, among other conditions.

CHARGE Syndrome

Often associated with a mutation in a gene known as CHD7, this consists of medical and physical conditions that differ from child to child. The CHARGE acronym comes from the first letter of some of the more common features seen in children:

  • CColoboma, or defects in the way the eye forms
  • HHeart defects
  • AAtresia of the choanae, or blocked nasal passages
  • RRetardation of growth and development
  • GGenital underdevelopment
  • EEar abnormalities

FOXN1 Deficiency

This condition affects the production of critical proteins, which may result in a severely compromised immune system and problems with the growth of hair and nails.

Diabetic Embryopathy

This condition may be associated with altered fetal thymus size and other congenital abnormalities. Abnormal thymic development has been seen in infants of diabetic mothers.

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Children with congenital athymia require special care.

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RETHYMIC is the first and only FDA-approved tissue-based treatment for congenital athymia engineered to help children develop an immune system sufficient to fight infections.

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RETHYMIC Connect™ provides support and resources to children with congenital athymia and their caregivers.

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Indication and Important Safety Information
Important Safety Information

Infection Control: Immune reconstitution sufficient to protect from infection usually develops between 6-12 months after treatment with RETHYMIC. For some children, it may take up to 2 years. Taking medications that prevent infection and other infection control measures, such as hand washing and isolation, should be continued until your child’s doctor confirms that immune function has been reconstituted through immune tests and the criteria for discontinuing certain medications have been met. Immediately report signs and symptoms of infection, such as fever, to your child’s doctor.

Graft versus Host Disease (GVHD): RETHYMIC may cause or make pre-existing GVHD worse. Your child will be monitored for GVHD and treated if needed. Symptoms of GVHD may include fever, rash, swollen lymph nodes, inflammation of the digestive system, and/or diarrhea.

Autoimmune Disorders: Autoimmune-related side effects (when your immune system attacks healthy cells by mistake) occurred in patients treated with RETHYMIC. These included low platelets, white blood cells, or red blood cells; protein in the urine; hair loss; poor thyroid function; inflammation of the liver, joints, or spinal cord; loss of pigment in the skin, eyes and hair; overactive thyroid function; and loss of function of the ovaries. Your doctor will monitor your child regularly.

Kidney Disease: Children with kidney disease have a higher risk of death when treated with RETHYMIC.

Cytomegalovirus (CMV) Infection: In clinical studies, 4 out of 4 patients with CMV infection prior to treatment with RETHYMIC died.

Cancer: Due to your child’s weakened immune system, there is an increased risk of developing blood cancer. Your child’s doctor will monitor your child through testing for Epstein-Barr virus and CMV, which are two viruses that can cause cancer.

Transmission of Serious Infections and Transmissible Infectious Diseases: Because RETHYMIC is made from human tissue, and animal products are used in the manufacturing process, transmission of infectious diseases may occur.

Vaccine Administration: Notify your child’s doctor to evaluate your child’s immune status before receiving vaccinations. Live virus vaccines should not be given until the doctor determines that your child has met criteria for and received inactivated vaccines.

Anti-HLA Antibodies: Before receiving RETHYMIC, your child will be tested for HLA antibodies, which are proteins that may be present in your child’s blood. If your child has these antibodies, your child should receive RETHYMIC from a specific donor, which will be determined by your child’s doctor.

HLA Typing: If your child received a hematopoietic cell transplantation (HCT) or a solid organ transplant, testing to match your child with RETHYMIC from a compatible donor is required. Children who have received an HCT are at an increased risk of developing GVHD after RETHYMIC if the HCT donor does not fully match with RETHYMIC.

Deaths: Of the 105 children who participated in the clinical studies, 29 patients died, including 23 in the first year after implantation of RETHYMIC.

The most common side effects are high blood pressure, cytokine release syndrome, rash, low magnesium, decrease in kidney function, low platelets, and GVHD.

These are not all the possible side effects of RETHYMIC. Talk to your child’s doctor about any side effect that bothers your child or does not go away.

You are encouraged to report side effects to the FDA at 1-800-FDA-1088 or www.fda.gov/safety/medwatch.

Indication

RETHYMIC® is indicated for immune reconstitution in pediatric patients with congenital athymia.

RETHYMIC is not for use in patients who have been diagnosed with severe combined immunodeficiency (SCID).

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