PMC8295470_01
Principal clinical events and therapeutic strategies timeline: (1) Hodgkin's lymphoma treated with six cycles of doxorubicin, bleomycin, vinblastine, dacarbazine (ABVD), two cycles of ifosfamide, epirubicin, and etoposide (IEV); under stable remission after HSCT. (2) AHA, ITP treated with steroids. (3) SLE treated with hydroxychloroquine, azathioprine, and prednisone at onset, then with hydroxychloroquine and short periods of low-dose prednisone until the end of 2018. (4) Recurrent episodes of fever, diffuse arthralgias, myalgias, respiratory infections, MAS-like, chilblain lupus persisted despite treatment trials with high-dose steroids, methotrexate, mycophenolate mofetil, and anakinra. The last therapeutic attempt with azathioprine was interrupted because of side effects. SLE, systemic lupus erythematosus; AHA, autoimmune hemolytic anemia; ITP, immune-mediated thrombocytopenia; MAS, macrophage activation syndrome; DC, dilative cardiopathy; CT, chemotherapy; auto-HSCT, autologous stem cell transplantation; AZA, azathioprine; MTX, methotrexate; MMF, mycophenolate mofetil; A, anakinra; IG, immunoglobulin; T/S, trimethoprim/sulfamethoxazole.
fped-09-702546-g0001.jpg
PMC8295470_01_fped-09-702546-g0001.jpg
F1
Disease manifestations were poorly responsive to therapeutic attempts (Figure 1). Serum IFN-I signature was significantly increased despite steroid therapy, as shown by the overexpression of six interferon-stimulated genes (IFI27, IFI44L, IFIT1, ISG15, RSAD2, SIGLEC1) in peripheral blood (Supplementary Figure 1).
Mediastinal involvement. (A) Contrast enhancing subcarinal lymphadenopathy detected with CT scan performed in 2019 (white arrow). (B) One year follow up shows increased volume and intranodal calcification (gray arrow). No parenchymal abnormalities were found.
fped-09-702546-g0002.jpg
PMC8295470_01_fped-09-702546-g0002.jpg
F2
Mediastinal and right bronchial lymphadenopathies showed a growing pattern, and diffuse lymphoproliferation was documented at consecutive HRCTs (Figure 2).
Genetic analysis. (A) By cDNA analysis, two main abnormal splicing products were demonstrated (U as upper and L as lower band). The PIK3R1 cDNA sequence of interest is indicated below. (B) Sanger sequencing electropherograms showing the PIK3R1 heterozygous point mutation c.1300-2A>G at the splice acceptor site present in the proband (II.1) and not in the mother (I.2). Blood sample from the father was not available (C) The wt sequence shows the correctly spliced transcript including exon11. (D) The intronic mutation c.1300-2A>G upstream exon11, abolished normal RNA splicing, resulting in either complete skipping of the exon 11 or in the usage of a cryptic acceptor exonic site, circled in green in the WT sequence. (E) The activation of this alternative splice site leads to removal of 7 nucleotides in exon 11 (circled in red in the WT sequence) causing the overlapping sequences in E.
fped-09-702546-g0003.jpg
PMC8295470_01_fped-09-702546-g0003.jpg
F3
Further tests confirmed that the newly described mutation results in the skipping of exon 11 and other minor splicing products of p85alpha, leading to the diagnosis of APDS2 (Figure 3).