Defects of B-cell terminal differentiation in patients with type-1 Kabuki syndrome.
|Title||Defects of B-cell terminal differentiation in patients with type-1 Kabuki syndrome.|
|Publication Type||Journal Article|
|Year of Publication||2016|
|Authors||Lindsley AW, Saal HM, Burrow TA, Hopkin RJ, Shchelochkov O, Khandelwal P, Xie C, Bleesing J, Filipovich L, Risma K, Assa'ad AH, Roehrs PA, Bernstein JA|
|Journal||J Allergy Clin Immunol|
|Date Published||2016 Jan|
|Keywords||Abnormalities, Multiple, Adolescent, Adult, Agammaglobulinemia, B-Lymphocytes, Cell Differentiation, Child, Child, Preschool, DNA-Binding Proteins, Face, Hematologic Diseases, Humans, Infant, Mutation, Neoplasm Proteins, Vestibular Diseases, Young Adult|
BACKGROUND: Kabuki syndrome (KS) is a complex multisystem developmental disorder associated with mutation of genes encoding histone-modifying proteins. In addition to craniofacial, intellectual, and cardiac defects, KS is also characterized by humoral immune deficiency and autoimmune disease, yet no detailed molecular characterization of the KS-associated immune phenotype has been reported. OBJECTIVE: We sought to characterize the humoral immune defects found in patients with KS with lysine methyltransferase 2D (KMT2D) mutations. METHODS: We comprehensively characterized B-cell function in a cohort (n = 13) of patients with KS (age, 4 months to 27 years). RESULTS: Three quarters (77%) of the cohort had a detectable heterozygous KMT2D mutation (50% nonsense, 20% splice site, and 30% missense mutations), and 70% of the reported mutations are novel. Among the patients with KMT2D mutations (KMT2D(Mut/+)), hypogammaglobulinemia was detected in all but 1 patient, with IgA deficiency affecting 90% of patients and a deficiency in at least 1 other isoform seen in 40% of patients. Numbers of total memory (CD27(+)) and class-switched memory B cells (IgM(-)) were significantly reduced in patients with KMT2D(Mut/+) mutations compared with numbers in control subjects (P < .001). Patients with KMT2D(Mut/+) mutations also had significantly reduced rates of somatic hypermutation in IgG (P = .003) but not IgA or IgM heavy chain sequences. Impaired terminal differentiation was noted in primary B cells from patients with KMT2D(Mut/+) mutations. Autoimmune pathology was observed in patients with missense mutations affecting the SET domain and its adjacent domains. CONCLUSIONS: In patients with KS, autosomal dominant KMT2D mutations are associated with dysregulation of terminal B-cell differentiation, leading to humoral immune deficiency and, in some cases, autoimmunity. All patients with KS should undergo serial clinical immune evaluations.
|Alternate Journal||J. Allergy Clin. Immunol.|