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Congenital athymia

Congenital athymia is a rare metabolic disorder, frequently genetic, that disrupts normal biochemical pathways leading to multisystem involvement

Prevalence

unknown

Ultra-rare

US Estimated

Ultra-rare

Europe Estimated

Age of Onset

Neonatal

ICD-10

D82.1

D81.9

Inheritance Pattern

Autosomal dominant

Autosomal recessive

Mitochondrial/Multigenic

X-linked dominant

X-linked recessive

5 Facts you should know

FACT

1

Congenital athymia is defined by complete absence of functional thymic tissue, resulting in profound T-cell deficiency with preserved or near-normal B-cell and NK-cell numbers but severely impaired cellular immunity

FACT

2

It presents in early infancy with life-threatening infections, including opportunistic viral, fungal, and bacterial pathogens, and is often identified through abnormal newborn screening (low or absent TRECs)

FACT

3

Congenital athymia is etiologically heterogeneous, occurring as part of syndromic conditions such as 22q11.2 deletion syndrome, CHARGE syndrome, FOXN1 deficiency, or PAX1-related disorders

FACT

4

Hematopoietic stem cell transplantation alone is insufficient, as T-cell maturation requires thymic tissue; definitive immune reconstitution requires thymic tissue implantation rather than conventional HSCT

FACT

5

Early diagnosis and intervention are critical, as delayed recognition increases the risk of severe infections, immune dysregulation, and mortality; management requires specialized centers with expertise in immune reconstitution and long-term immune monitoring

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Congenital athymia is also known as...

Congenital athymia is also known as:

  • Complete athymia
  • Thymic aplasia
  • Complete DiGeorge syndrome

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Common signs & symptoms

Severe, recurrent infections

Failure to thrive

Chronic diarrhea

Persistent candidiasis

Absent or very low T-cell counts

Poor response to vaccines

Possible associated features

  • Congenital heart defects
  • Hypocalcemia
  • Craniofacial anomalies (depending on underlying syndrome)

Current treatments

Definitive therapy

• Cultured thymus tissue implantation (CTTI)

Supportive

  • Protective isolation
  • Infection prophylaxis
  • Avoid live vaccines

HSCT

  • Limited role unless thymic function restored

References:

Markert ML, Devlin BH, Chinn IK, et al. Thymus transplantation in complete DiGeorge anomaly: immunologic and safety outcomes. Blood. 2007;109(10):4539–4547. doi:10.1182/blood-2006-10-050021 Markert ML, Devlin BH, McCarthy EA. Thymus transplantation. Clin Immunol. 2010;135(2):236–246. doi:10.1016/j.clim.2010.02.006 Kuo CY, Chase J, Lloret MG, et al. Congenital athymia: immunologic phenotype, management, and outcomes. J Allergy Clin Immunol. 2021;147(4):1354–1364.e5. doi:10.1016/j.jaci.2020.09.042 Sullivan KE. Chromosome 22q11.2 deletion syndrome and DiGeorge syndrome. Immunol Rev. 2019;287(1):186–201. doi:10.1111/imr.12701 Buckley RH. The multiple causes of human SCID. J Clin Invest. 2004;114(10):1409–1411. doi:10.1172/JCI23590

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