ADA2 deficiency in a patient with Noonan syndrome-like disorder with loose anagen hair: The co-occurrence of two rare syndromes

Am J Med Genet A. 2019 Dec;179(12):2474-2480. doi: 10.1002/ajmg.a.61363. Epub 2019 Oct 4.


Noonan syndrome-like disorder with loose anagen hair (NS/LAH) is one of the RASopathies, a group of clinically related developmental disorders caused by germline mutations in genes that encode components acting in the RAS/MAPK pathway. Among RASopathies, NS/LAH (OMIM 607721) is an extremely rare, multiple anomaly syndrome characterized by dysmorphic facial features similar to those observed in Noonan syndrome along with some distinctive ectodermal findings including easily pluckable, sparse, thin, and slow-growing hair. ADA2 deficiency (DADA2, OMIM 615688) is a monogenic autoinflammatory disorder caused by homozygous or compound heterozygous mutations in ADA2, with clinical features including recurrent fever, livedo racemosa, hepatosplenomegaly, and strokes as well as immune dysregulation. This is the first report of NS/LAH and ADA2 deficiency in the same individual. We report on a patient presenting with facial features, recurrent infections and ectodermal findings in whom both the clinical and molecular diagnoses of NS/LAH and ADA2 deficiency were established, respectively.

Keywords: ADA2; SHOC2; DADA2; Noonan syndrome-like disorder with loose anagen hair; consanguinity.

Publication types

  • Case Reports

MeSH terms

  • Adenosine Deaminase / deficiency*
  • Adenosine Deaminase / genetics
  • Agammaglobulinemia / diagnosis*
  • Agammaglobulinemia / genetics*
  • Alleles
  • Genetic Association Studies / methods
  • Genetic Predisposition to Disease
  • Genotype
  • Humans
  • Intercellular Signaling Peptides and Proteins / deficiency*
  • Loose Anagen Hair Syndrome / diagnosis*
  • Loose Anagen Hair Syndrome / genetics*
  • Mutation
  • Noonan Syndrome / diagnosis*
  • Noonan Syndrome / genetics*
  • Phenotype*
  • Radiography
  • Severe Combined Immunodeficiency / diagnosis*
  • Severe Combined Immunodeficiency / genetics*
  • Symptom Assessment


  • Intercellular Signaling Peptides and Proteins
  • ADA2 protein, human
  • Adenosine Deaminase

Supplementary concepts

  • Severe combined immunodeficiency due to adenosine deaminase deficiency