Case Report: Hypomorphic Function and Somatic Reversion in DOCK8 Deficiency in One Patient With Two Novel Variants and Sclerosing Cholangitis

DOCK8 deficiency is a combined immunodeficiency due to biallelic variants in dedicator of cytokinesis 8 (DOCK8) gene. The disease has a wide clinical spectrum encompassing recurrent infections (candidiasis, viral and bacterial infections), virally driven malignancies and immune dysregulatory features, including autoimmune (cytopenia and vasculitis) as well as allergic disorders (eczema, asthma, and food allergy). Hypomorphic function and somatic reversion of DOCK8 has been reported to result in incomplete phenotype without IgE overproduction. Here we describe a case of DOCK8 deficiency in a 8-year-old Caucasian girl. The patient's disease was initially classified as autoimmune thrombocytopenia, which then evolved toward a combined immunodeficiency phenotype with recurrent infections, persistent EBV infection and lymphoproliferation. Two novel variants (one deletion and one premature stop codon) were characterized, resulting in markedly reduced, but not absent, DOCK8 expression. Somatic reversion of the DOCK8 deletion was identified in T cells. Hypomorphic function and somatic reversion were associated with restricted T cell repertoire, decreased STAT5 phosphorylation and impaired immune synapse functioning in T cells. Although the patient presented with incomplete phenotype (absence of markedly increase IgE and eosinophil count), sclerosing cholangitis was incidentally detected, thus indicating that hypomorphic function and somatic reversion of DOCK8 may delay disease progression but do not necessarily prevent from severe complications.

Generation of 3 clones of induced pluripotent stem cells (iPSCs) from a patient affected by Autosomal Recessive Osteopetrosis due to mutations in TCIRG1 gene

Autosomal recessive osteopetrosis (ARO) is a rare inherited disorder leading to increased bone density with impairment in bone resorption. Among the genes responsible for ARO, the TCIRG1 gene, coding for the a3 subunit of the osteoclast proton pump, is mutated in more than 50% of the cases, increasing the importance of TCIRG1-iPSCs as disease model. We generated 3 iPSC clones derived from Peripheral Blood Mononuclear Cells (PBMCs) of a patient carrying the heterozygous mutations p.Y512X and c.2236 + 1G > A. A Sendai virus-based vector was used and the iPSCs were characterized for genetic identity to parental cells, genomic integrity, pluripotency, and differentiation ability.

Generation of induced Pluripotent Stem Cells (UNIBSi008-A, UNIBSi008-B, UNIBSi008-C) from an Ataxia-Telangiectasia (AT) patient carrying a novel homozygous deletion in ATM gene

Using a Sendai Virus based vector delivering Yamanaka Factors, we generated induced Pluripotent Stem Cells (iPSCs) from peripheral blood mononuclear cells of a patient affected by Ataxia Telangiectasia (AT), caused by a novel homozygous deletion in ATM, spanning exons 5-7. Three clones were fully characterized for pluripotency and capability to differentiate. These clones preserved the causative mutation of parental cells and genomic stability over time (>100 passages). Furthermore, in AT derived iPSCs we confirmed the impaired DNA damage response after ionizing radiation. All these data underline potential usefulness of our clones as in vitro AT disease model.

Generation of three iPSC lines from fibroblasts of a patient with Aicardi Goutières Syndrome mutated in TREX1

Fibroblasts from a patient with Aicardi Goutières Syndrome (AGS) carrying a compound heterozygous mutation in TREX1, were reprogrammed into induced pluripotent stem cells (iPSCs) to establish isogenic clonal stem cell lines: UNIBSi006-A, UNIBSi006-B, and UNIBSi006-C. Cells were transduced using the episomal Sendai viral vectors, containing human OCT4, SOX2, c-MYC and KLF4 transcription factors. The transgene-free iPSC lines showed normal karyotype, expressed pluripotent markers and displayed in vitro differentiation potential toward cells of the three embryonic germ layers.

Generation of induced pluripotent stem cells (iPSCs) from patient with Cri du Chat Syndrome

The Cri du Chat Syndrome (CdCS) is a genetic disease resulting from variable size deletion occurring on the short arm of chromosome 5. The main clinical features are a high-pitched monochromatic cry, microcephaly, severe psychomotor and mental retardation with characteristics of autism spectrum disorders such as hand flapping, obsessive attachments to objects, twirling objects, repetitive movements, and rocking. We reprogrammed to pluripotency peripheral blood mononuclear cells derived from a patient carrying large deletion on the short arm of chromosome 5, using a commercially available non-integrating expression system. The iPSCs expressed pluripotency markers and differentiated in the three embryonic germ layers.