Immunologic Heterogeneity in 2 Cartilage-Hair Hypoplasia Patients With a Distinct Clinical Course

A. Gamliel, Y. N. Lee, A. Lev, O. Abuzaitun, E. Rechavi, S. Levy, A. J. Simon*, R. Somech*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Introduction: Cartilage-hair hypoplasia (CHH) syndrome is a rare autosomal recessive syndrome associated with skeletal dysplasia, varying degrees of combined immunodeficiency (CID), short stature, hair hypoplasia, macrocytic anemia, increased risk of malignancies, and Hirschsprung disease. Purpose: To provide clinical and immunological insights obtained from 2 unrelated patients who displayed clinical characteristics of CHH. Methods: Two patients with suspected CHH syndrome due to skeletal dysplasia and immunodeficiency underwent an immunological and genetic work-up using flow cytometry, next-generation sequencing (NGS) of the immune repertoire, and Sanger sequencing to identify the underlying defects. Results: Patient 1 presented with low birth weight and skeletal dysplasia. Newborn screening was suggestive of T-cell immunodeficiency, as T-cell receptor excision circle levels were undetectable. Both the T-cell receptor (TCR) Vß and TCR-g (TRG) repertoires were restricted, with evidence of clonal expansion. Genetic analysis identified compound heterozygous RMRP variants inherited from both parents. Patient 2 presented with recurrent lung and gastrointestinal infections, skeletal dysplasia, failure to thrive, and hepatomegaly. The polyclonal pattern of the TCRß repertoire was normal, with only slight overexpression of TCR-ßV20 and restricted expression of Vßs. TRG expressed a normal diverse repertoire, similar to that of the healthy control sample. Genetic analysis identified biallelic novel regulatory variants in RMRP. Both parents are carriers of this mutation. Conclusion: Our findings demonstrate how the immunological work-up, supported by genetic findings, can dramatically change treatment and future outcome in patients with the same clinical syndrome.

Original languageEnglish
Pages (from-to)263-270
Number of pages8
JournalJournal of Investigational Allergology and Clinical Immunology
Volume33
Issue number4
DOIs
StatePublished - 2023

Keywords

  • Cartilage-Hair Hypoplasia (CHH)
  • NGS
  • RMRP
  • Severe combined immunodeficiency (SCID)
  • TCR repertoire

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