A Novel Homozygous TTC7A Missense Mutation Results in Familial Multiple Intestinal Atresia and Combined Immunodeficiency.

Rare autosomal-recessive variants in tetratricopeptide repeat domain 7A (TTC7A) gene have been shown to cause intestinal and immune disorders of variable severity. Missense mutations in TTC7A gene, usually retaining most of the functional motifs, is associated with relative milder clinical presentations. In this study, we reported a patient who was suffering from severe multiple intestinal atresia (MIA) with combined immunodeficiency (CID) that led to the pyloric diaphragm, ileum atresia, colon stenosis, and multiple episodes of sepsis. In spite of several surgeries and supportive treatment, the patient died of severe sepsis and multiple organ failure at age of 3 months. The whole exome sequencing (WES) of peripheral blood samples identified a novel homozygous TTC7A missense mutation (c. 206T>C, p. L69P), inherited from his parents with consanguineous marriage. In silico analysis revealed that a hydrogen bond present between Gly65 and Leu69 in the wild-type TTC7A was disrupted by the Leu69Pro mutation. Moreover, this homozygous missense mutation led to a reduced TTC7A expression in lymphocytes and intestinal tissues, accompanied by impeded lymphocyte development. Further studies demonstrated that the PI4K-FAM126A-EFR3A pathway was impaired in colon tissues. Our data strongly support the linkage of severe MIA-CID with the missense mutation in TTC7A gene. More knowledge of the TTC7A protein functions will have important therapeutic implications for patients with MIA-CID.

Immunoregulation effects of different γδT cells and toll-like receptor signaling pathways in neonatal necrotizing enterocolitis.

The aim of the study was to observe cytokine and T-cell-related toll-like-receptor (TLR) changes in intestinal samples of neonatal necrotizing enterocolitis patients.Four necrotic bowels were collected from neonatal NEC patients with gestational ages of 28 to 29 weeks in our hospital, whereas 4 neonatal patients who underwent intestinal atresia surgery served as the controls. Intestinal flora was examined and IL-1, IL-2, IL-4, IL-6, IL-8, IL-10, TNF-α, IFN-γ, and IL-17 expressions in resected intestine samples, as well as in isolated gamma delta T (γδT) cells, were analyzed immunohistochemically and via quantitative RT-PCR. γδT cells were isolated from the intestinal intraepithelial lymphocytes (IELs) and their TLR4/TLR9 distribution in the intestinal tissues was determined by flow cytometry.The bacterial flora of the neonatal NEC patients' contained significantly higher amounts of Gram-negative Enterobacteriaceae, Klebsiella, and Bacteroides but anaerobic Gram-positive Bifidobacteria occurred significantly less in the NEC than the control group. IL-1, IL-2, IL-4, IL-6, IL-8, IL-10, TNF-α, IFN-γ, and IL-17 expressions in the resected intestine samples and in isolated γδT cells were enhanced in NEC samples compared to the controls. γδT cells were less prevalent in NEC-derived intestinal tissues, but their TLR4/TLR9 expressions were significantly enhanced.The changed bacterial flora in preterm neonatal NEC patients led to an obvious inflammation of the intestines, which was accompanied by reductions of γδT cell localizations to the intestine and a shift of their surface expressions to TLR4 and TLR9.

TTC7A mutations disrupt intestinal epithelial apicobasal polarity.

Multiple intestinal atresia (MIA) is a rare cause of bowel obstruction that is sometimes associated with a combined immunodeficiency (CID), leading to increased susceptibility to infections. The factors underlying this rare disease are poorly understood. We characterized the immunological and intestinal features of 6 unrelated MIA-CID patients. All patients displayed a profound, generalized lymphocytopenia, with few lymphocytes present in the lymph nodes. The thymus was hypoplastic and exhibited an abnormal distribution of epithelial cells. Patients also had profound disruption of the epithelial barrier along the entire gastrointestinal tract. Using linkage analysis and whole-exome sequencing, we identified 10 mutations in tetratricopeptide repeat domain­7A (TTC7A), all of which potentially abrogate TTC7A expression. Intestinal organoid cultures from patient biopsies displayed an inversion of apicobasal polarity of the epithelial cells that was normalized by pharmacological inhibition of Rho kinase. Our data indicate that TTC7A deficiency results in increased Rho kinase activity, which disrupts polarity, growth, and differentiation of intestinal epithelial cells, and which impairs immune cell homeostasis, thereby promoting MIA-CID development.

Pathological analysis of umbilical cord ulceration associated with fetal duodenal and jejunal atresia.

Umbilical cord ulceration is a serious complication of fetal intestinal atresia. To elucidate the relationship between fetal intestinal atresia and umbilical cord ulceration grade, we pathologically examined umbilical cords in 15 duodenal and 5 jejunal atresia cases and 28 control cases. Microscopic examination of the umbilical cords of patients with intestinal atresia revealed high-grade ulceration and a significant increase in macrophage numbers (P = 0.0087). Transudation of red blood cells was not associated with any specific clinical diagnosis, but was seen in all high-grade ulceration cases. It is suggested that clinical symptoms become apparent following gradual pathological changes.

Hereditary multiple intestinal atresias: 2 new cases and review of the literature.

Intestinal atresias are a common cause of newborn bowel obstruction (Dalla Vecchia LK, Grosfeld JL, West KW, et al, Intestinal atresia and stenosis: a 25-year experience with 277 cases. Arch Surg 1998; 133[5]:490-496). Hereditary multiple intestinal atresias, first reported by Guttman et al in 1973, is the rarest form of multiple atresias (Guttman FM, Braun P, Garance PH, et al, Multiple atresias and a new syndrome of hereditary multiple atresias involving the gastrointestinal tract from stomach to rectum. J Pediatr Surg 1973;8:633-640; Bass J, Pyloric atresia associated with multiple intestinal atresias and immune deficiency. J Pediatr Surg 2002;37:941-942.). It has been proposed to be autosomal recessive, to involve atresias in a variable combination of sites from stomach to rectum, and to be universally fatal (Bilodeau A, Prasil P, Cloutier R, et al, Hereditary multiple intestinal atresia: thirty years later. J Pediatr Surg 2004;39:726-730; Moreno LA, Gottrand F, Turck D, et al, Severe combined immunodeficiency syndrome associated with autosomal recessive familial multiple gastrointestinal atresias: study of a family. Am J Med Genet 1990;37:143-146). Patients have significant intestinal dysfunction and unrelenting sepsis stemming from a poorly defined, severe immunologic defect. Our case report presents 2 full siblings to nonconsanguineous parents with pyloric atresia, multiple small bowel and colonic atresias, and severe immune dysfunction. Care was withdrawn within 3 months of life on both siblings after multiple bouts of sepsis. Data suggest that the immune defect may not be primary, but in fact be secondary to intestinal dysfunction. Although the subjects in this article ultimately had fatal outcomes, a comprehensive immunologic/physiologic picture is presented in hopes of furthering the understanding of this grave disease.

Donor immune reconstitution after liver-small bowel transplantation for multiple intestinal atresia with immunodeficiency.

The syndrome of multiple intestinal atresia with immunodeficiency is a rare, invariably fatal congenital disorder. At 16 months of age, a child with this syndrome underwent liver-small bowel transplantation from a 1-of-6 HLA-matched donor. He acquired full enteral tolerance and normal liver function and has never shown evidence of allograft rejection. After mild graft-versus-host disease developed, studies revealed that more than 99% of his CD3(+) lymphocytes and 50% of his CD19(+) lymphocytes were of donor origin, whereas granulocytes and monocytes remained of recipient origin. He synthesizes polyclonal immunoglobulin G (IgG), IgA, and IgM and has developed antibodies to cytomegalovirus (CMV) and parainfluenza 3. His T lymphocytes are predominately CD3(+)CD4(-)CD8(-) with T-cell receptor gammadelta heterodimers and CD3(+)CD4(-)CD8(+) with CD8alphaalpha homodimers, populations consistent with an intraepithelial lymphocyte phenotypic profile. We postulate that he has engrafted a donor intestine-derived immune system and is incapable of rejecting his engrafted organs.

A syndrome involving immunodeficiency and multiple intestinal atresias.

Multiple intestinal atresias (MIA) is a severe form of intestinal atresias throughout the gastrointestinal tract. In two reports, MIA have been associated with severe immunodeficiency. We report a newborn girl who had profound humoral and B cell immunodeficiency and impaired T cell function. The patient had agammaglobulinemia and decreased blood lymphocytes, with virtually no B cells in the blood or in intestinal lymph nodes. T cells were reduced in number and weakly proliferated to mitogens. These data suggest that a syndrome involving the development of MIA is associated with various forms of severe immunodeficiency, and therefore newborns with MIA should be examined for immunodeficiency.

Multiple areas of intestinal atresia associated with immunodeficiency and posttransfusion graft-versus-host disease.

We describe an infant with multiple segmental areas of atresia of the small and large bowel, with histologic features characteristic of the hereditary form of the disease. Posttransfusion graft-versus-host disease developed first, and then immunodeficiency was found. This report confirms the association between hereditary multiple intestinal atresia and immunodeficiency. We recommend irradiation of blood products in patients with multiple intestinal atresia pending evaluation of immune system status.