Differential Effects of HDAC6 Inhibition Versus Knockout During Hepatic Ischemia-reperfusion Injury Highlight Importance of HDAC6 C-terminal Zinc-finger Ubiquitin-binding Domain

BACKGROUND

Ischemia-reperfusion injury (IRI) causes significant morbidity in liver transplantation among other medical conditions. IRI following liver transplantation contributes to poor outcomes and early graft loss. Histone/protein deacetylases (HDACs) regulate diverse cellular processes, play a role in mediating tissue responses to IRI, and may represent a novel therapeutic target in preventing IRI in liver transplantation.

METHODS

Using a previously described standardized model of murine liver warm IRI, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were assessed at 24 and 48 h after reperfusion to determine the effect of different HDAC inhibitors.

RESULTS

Broad HDAC inhibition with trichostatin-A (TSA) was protective against hepatocellular damage (P < 0.01 for AST and P < 0.05 for ALT). Although HDAC class I inhibition with MS-275 provided statistically insignificant benefit, tubastatin-A (TubA), an HDAC6 inhibitor with additional activity against HDAC10, provided significant protection against liver IRI (P < 0.01 for AST and P < 0.001 for ALT). Surprisingly genetic deletion of HDAC6 or -10 did not replicate the protective effects of HDAC6 inhibition with TubA, whereas treatment with an HDAC6 BUZ-domain inhibitor, LakZnFD, eliminated the protective effect of TubA treatment in liver ischemia (P < 0.01 for AST and P < 0.01 for ALT).

CONCLUSIONS

Our findings suggest TubA, a class IIb HDAC inhibitor, can mitigate hepatic IRI in a manner distinct from previously described class I HDAC inhibition and requires the HDAC6 BUZ-domain activity. Our data corroborate previous findings that HDAC targets for therapeutic intervention of IRI may be tissue-specific, and identify HDAC6 inhibition as a possible target in the treatment of liver IRI.

Phenotypic Characterization of Congenital Hyperinsulinism Due to Novel Activating Glucokinase Mutations

The importance of glucokinase (GK) in the regulation of insulin secretion has been highlighted by the phenotypes of individuals with activating and inactivating mutations in the glucokinase gene (GCK). Here we report 10 individuals with congenital hyperinsulinism (HI) caused by eight unique activating mutations of GCK. Six are novel and located near previously identified activating mutations sites. The first recognized episode of hypoglycemia in these patients occurred between birth and 24 years, and the severity of the phenotype was also variable. Mutant enzymes were expressed and purified for enzyme kinetics in vitro. Mutant enzymes had low glucose half-saturation concentration values and an increased enzyme activity index compared with wild-type GK. We performed functional evaluation of islets from the pancreata of three children with GCK-HI who required pancreatectomy. Basal insulin secretion in perifused GCK-HI islets was normal, and the response to glyburide was preserved. However, the threshold for glucose-stimulated insulin secretion in perifused glucokinase hyperinsulinism (GCK-HI) islets was decreased, and glucagon secretion was greatly suppressed. Our evaluation of novel GCK disease-associated mutations revealed that the detrimental effects of these mutations on glucose homeostasis can be attributed not only to a lowering of the glucose threshold of insulin secretion but also to a decreased counterregulatory glucagon secretory response.

ARTICLE HIGHLIGHTS

Our evaluation of six novel and two previously published activating GCK mutations revealed that the detrimental effects of these mutations on glucose homeostasis can be attributed not only to a lowering of the glucose threshold of insulin secretion but also to a decreased counterregulatory glucagon secretory response. These studies provide insights into the pathophysiology of GCK-hyperinsulinism and the dual role of glucokinase in β-cells and α-cells to regulate glucose homeostasis.

Clinicopathologic Characteristics of Pediatric Follicular Variant of Papillary Thyroid Carcinoma Subtypes: A Retrospective Cohort Study

Introduction: Follicular patterned thyroid nodules with nuclear features of papillary thyroid carcinoma (PTC) encompass a range of diagnostic categories with varying risks of metastatic behavior. Subtypes include the invasive encapsulated follicular variant of PTC (Ienc-fvPTC) and infiltrative fvPTC (inf-fvPTC), with tumors lacking invasive features classified as noninvasive follicular thyroid neoplasms with papillary-like features (NIFTPs). This study aimed to report the clinical and histological features of pediatric cases meeting criteria for these histological subtypes, with specific focus on Ienc-fvPTC and inf-fvPTC. Methods: In this retrospective cohort study, pediatric patients with thyroid neoplasms showing follicular patterned growth and nuclear features of PTC noted on surgical pathology between January 2010 and January 2021 were retrospectively reviewed and classified according to the recent 2022 World Health Organization (WHO) criteria. Clinical and histopathologic parameters were described for NIFTP, Ienc-fvPTC, and inf-fvPTC subtypes, with specific comparison of Ienc-fvPTC and inf-fvPTC cases. Results: The case cohort included 42 pediatric patients, with 6 (14%), 25 (60%), and 11 (26%) patients meeting criteria for NIFTP, Ienc-fvPTC, and inf-fvPTC, respectively. All cases were rereviewed, and 5 patients originally diagnosed with Ienc-fvPTC before 2017 were reappraised as having NIFTPs. The NIFTP cases were encapsulated tumors without invasive features, lymph node or distant metastasis, or disease recurrence. Ienc-fvPTC tumors demonstrated clearly demarcated tumor capsules and capsular/vascular invasion, while inf-fvPTC tumors displayed infiltrative growth lacking a capsule. inf-fvPTC cases had increased prevalence of malignant preoperative cytology, lymph node metastasis, and distant metastasis (p < 0.01). These cases were treated with total thyroidectomy, lymph node dissection, and subsequent radioactive iodine therapy. Preliminary genetic findings suggest a predominance of fusions in inf-fvPTC cases versus point mutations in Ienc-fvPTC (p = 0.02). Conclusions: Pediatric NIFTP and fvPTC subtypes appear to demonstrate alignment between clinical and histological risk stratification, with indolent behavior in Ienc-fvPTC and invasive features in inf-fvPTC tumors.

Coil-Localized Laparoscopic-Assisted Resection of Symptomatic Gastrointestinal Vascular Malformations in Children and Young Adults

Gastrointestinal (GI) bleeding from pediatric vascular malformation is uncommon and difficult to diagnose and manage. The preferred treatment is surgical resection; however, it can be challenging to precisely localize the lesion, particularly if it is not serosal.

Objectives

To describe a technique of intentional preoperative coil localization of symptomatic pediatric GI vascular malformations by pediatric interventional radiology to facilitate fluoroscopically assisted laparoscopic resection.

Methods

We searched the electronic privacy information center and picture archive and communication system in our center and found 3 cases. The electronic privacy information center and picture archive and communication system databases were the sources for retrieval of demographic, medical, radiological, and procedural information in all 3 cases.

Results

After many nondiagnostic investigations in all 3 patients, a GI vascular malformation as a cause of GI bleeding was diagnosed with computed tomography angiography/magnetic resonance angiography and catheter angiography. A preoperative 0.018-inch Hilal coil was placed as close as possible to the vascular malformation during super selective angiography. Laparoscopic surgery was performed within 24 hours of coil placement. In all cases, histology confirmed the resected bowel lesions to be vascular malformations.

Conclusions

Intentional endovascular coil localization has the potential to increase the precision of lesion localization and may reduce laparoscopic operative time, when guided by the coil position.

Thyroid Lobectomy for T1 Papillary Thyroid Carcinoma in Pediatric Patients

Importance

The current recommendation for pediatric patients with papillary thyroid cancer (PTC) is a total thyroidectomy. This recommendation applies to all stages of PTC, including papillary thyroid microcarcinoma (≤1 cm, T1a) tumors.

Objective

To evaluate the characteristics of American Joint Committee on Cancer T1 PTC tumors in a large pediatric population and to identify a subgroup of patients who may benefit from a thyroid lobectomy instead of a total thyroidectomy.

Design, Setting, and Participants

This retrospective cohort study was conducted from January 1, 2009, to May 31, 2020. The study took place at a tertiary care medical center and included 102 patients who were surgically treated for T1 PTC: 52 with stage T1a (≤1 cm) tumors and 50 with stage T1b (>1 cm but ≤2 cm) tumors.

Main Outcomes and Measures

Primary outcomes included the presence of bilateral disease and lymph node metastasis.

Results

A total of 102 patients (mean age, 15.3 years [range, 9.7-18.9 years]; 84 girls [82.4%]) were included in the analysis. Among 52 patients with T1a tumors, 10 (19.2%) had bilateral disease, and 15 (28.8%) had central neck lymph node (N1a) metastasis. Among 50 patients with T1b tumors, 10 (20%) had bilateral and 13 (26%) had N1a disease. Of those with T1a, unilateral multifocality was associated with bilateral disease (odds ratio [OR], 2.1; 95% CI, 1.3-3.4) and N1a disease (OR, 5.1; 95% CI, 1.5-17.6). Both N1a disease (OR, 20.0; 95% CI, 3.5-115.0) and ≥4 positive lymph nodes (OR, 8.6; 95% CI, 1.2-60.9) were associated with bilateral disease. In patients with no pathologic evidence of lymph node metastasis (N0), there was a 95% rate of unilateral PTC. In patients with T1b tumors, unilateral multifocality was also associated with bilateral disease (OR, 1.8; 95% CI, 1.3-2.7). Patients with T1b tumors had an increased risk of lateral (N1b) neck lymph node metastasis when compared with those with T1a tumors (OR, 3.7; 95% CI, 1.0-14.5).

Conclusions and Relevance

The findings of this cohort study suggest that, in patients with unifocal T1a PTC without clinically evident nodal disease on preoperative ultrasonography, a thyroid lobectomy and central neck dissection may be considered. If there is no evidence of unilateral multifocality or if there are fewer than 4 positive lymph nodes on postoperative pathology, then close observation may be considered. These findings have substantial clinical implications and may result in practice changes regarding the extent of thyroid surgery on low-stage pediatric PTC.

Obesity-related IL-18 Impairs Treg Function and Promotes Lung Ischemia-reperfusion Injury

RATIONALE

Primary graft dysfunction (PGD) is a severe form of acute lung injury, leading to increased early morbidity and mortality after lung transplantation. Obesity is a major health problem, and recipient obesity is one of the most significant risk factors for developing PGD.

OBJECTIVES

We hypothesized that T-regulatory (Treg) cells are able to dampen early ischemia/reperfusion events and thereby decrease risk of PGD, whereas that action is impaired in obese recipients.

METHODS

We evaluated Treg, T cells and inflammatory markers, plus clinical data, in 79 lung and 41 liver or kidney transplant recipients and studied two groups of mice on high fat diet (HFD), who developed ("inflammatory" HFD) or not ("healthy" HFD) low-grade inflammation with decreased Treg function.

RESULTS

We identified increased levels of IL-18 as a previously unrecognized mechanism that impairs Treg suppressive function in obese individuals. IL-18 decreases levels of FOXP3, the key Treg transcription factor, decreases FOXP3 di- and oligomerization and increases the ubiquitination and proteasomal degradation of FOXP3. IL-18-treated Tregs or Treg from obese mice fail to control PGD, while IL-18 inhibition ameliorates lung inflammation. The IL-18 driven impairment in Treg suppressive function pre-transplant was associated with increased risk and severity of PGD in clinical lung transplant recipients.

CONCLUSION

Obesity-related IL-18 induces Treg dysfunction that may contribute to the pathogenesis of PGD. Evaluation of Treg suppressive function along with IL-18 levels may serve as screening tools to identify pre-transplant obese recipients with increased risk of PGD.

HDAC2 targeting stabilizes the CoREST complex in renal tubular cells and protects against renal ischemia/reperfusion injury

Histone/protein deacetylases (HDAC) 1 and 2 are typically viewed as structurally and functionally similar enzymes present within various co-regulatory complexes. We tested differential effects of these isoforms in renal ischemia reperfusion injury (IRI) using inducible knockout mice and found no significant change in ischemic tolerance with HDAC1 deletion, but mitigation of ischemic injury with HDAC2 deletion. Restriction of HDAC2 deletion to the kidney via transplantation or PAX8-controlled proximal renal tubule-specific Cre resulted in renal IRI protection. Pharmacologic inhibition of HDAC2 increased histone acetylation in the kidney but did not extend renal protection. Protein analysis demonstrated increased HDAC1-associated CoREST protein in HDAC2-/- versus WT cells, suggesting that in the absence of HDAC2, increased CoREST complex occupancy of HDAC1 can stabilize this complex. In vivo administration of a CoREST inhibitor exacerbated renal injury in WT mice and eliminated the benefit of HDAC2 deletion. Gene expression analysis of endothelin showed decreased endothelin levels in HDAC2 deletion. These data demonstrate that contrasting effects of HDAC1 and 2 on CoREST complex stability within renal tubules can affect outcomes of renal IRI and implicate endothelin as a potential downstream mediator.

Excision and Reconstruction of Alveolar Rhabdomyosarcoma Involving the Achilles Tendon in a Pediatric Patient: A Case Report

CASE

We describe a case of a 9-year-old boy who presented with a left calf mass consistent with alveolar rhabdomyosarcoma involving the Achilles tendon. The patient underwent radical resection of the Achilles tendon and Achilles tendon allograft reconstruction. At 2.5-year follow-up, the child had full ankle range of motion and strength and no signs of disease.

CONCLUSIONS

Radical resection of Achilles tendon in the setting of malignancy and reconstruction with allograft is a rare procedure that has not been previously described in the pediatric population. Orthopaedic oncologists can consider this option for the rare malignancies involving the Achilles tendon.

MEF2D sustains activation of effector Foxp3+ Tregs during transplant survival and anticancer immunity

The transcription factor MEF2D is important in the regulation of differentiation and adaptive responses in many cell types. We found that among T cells, MEF2D gained new functions in Foxp3+ T regulatory (Treg) cells due to its interactions with the transcription factor Foxp3 and its release from canonical partners, like histone/protein deacetylases. Though not necessary for the generation and maintenance of Tregs, MEF2D was required for the expression of IL-10, CTLA4, and Icos, and for the acquisition of an effector Treg phenotype. At these loci, MEF2D acted both synergistically and additively to Foxp3, and downstream of Blimp1. Mice with the conditional deletion in Tregs of the gene encoding MEF2D were unable to maintain long-term allograft survival despite costimulation blockade, had enhanced antitumor immunity in syngeneic models, but displayed only minor evidence of autoimmunity when maintained under normal conditions. The role played by MEF2D in sustaining effector Foxp3+ Treg functions without abrogating their basal actions suggests its suitability for drug discovery efforts in cancer therapy.

A Novel Homozygous Missense Mutation in the YARS Gene: Expanding the Phenotype of YARS Multisystem Disease

Aminoacyl-tRNA synthetases (ARSs) are crucial enzymes for protein translation. Mutations in genes encoding ARSs are associated with human disease. Tyrosyl-tRNA synthetase is encoded by YARS which is ubiquitously expressed and implicated in an autosomal dominant form of Charcot-Marie-Tooth and autosomal recessive YARS-related multisystem disease.

We report on a former 34-week gestational age male who presented at 2 months of age with failure to thrive (FTT) and cholestatic hepatitis. He was subsequently diagnosed with hyperinsulinemic hypoglycemia with a negative congenital hyperinsulinism gene panel and F-DOPA positron-emission tomography (PET) scan that did not demonstrate a focal lesion. Autopsy findings were notable for overall normal pancreatic islet size and morphology. Trio whole exome sequencing identified a novel homozygous variant of uncertain significance in YARS (c.611A > C, p.Tyr204Cys) with each parent a carrier for the YARS variant. Euglycemia was maintained with diazoxide (max dose, 18 mg/kg/day), and enteral dextrose via gastrostomy tube (G-Tube). During his prolonged hospitalization, the patient developed progressive liver disease, exocrine pancreatic insufficiency, acute renal failure, recurrent infections, ichthyosis, hematologic concerns, hypotonia, and global developmental delay. Such multisystem features have been previously reported in association with pathogenic YARS mutations. Although hypoglycemia has been associated with pathogenic YARS mutations, this report provides more conclusive data that a YARS variant can cause hyperinsulinemic hypoglycemia. This case expands the allelic and clinical heterogeneity of YARS-related disease. In addition, YARS-related disease should be considered in the differential of hyperinsulinemic hypoglycemia associated with multisystem disease.

Case Report: Two Distinct Focal Congenital Hyperinsulinism Lesions Resulting From Separate Genetic Events

Focal hyperinsulinism (HI) comprises nearly 50% of all surgically treated HI cases and is cured if the focal lesion can be completely resected. Pre-operative localization of the lesion is thus critical. Few cases of hyperinsulinism with multiple focal lesions have been reported, and assessment of the molecular mechanisms driving this rare occurrence has been limited. We present two cases of multifocal HI, each resulting from two independent, pancreatic focal lesions. ¹⁸Fluoro-dihydroxyphenylalanine positron emission tomography/computed tomography detected both lesions preoperatively in one patient, whereas identification of the second lesion was an incidental finding during surgical exploration in the other. Complete resection of the focal lesions resulted in cure of the HI in both cases. In each patient, genetic testing of the individual focal lesions revealed different regions of loss of heterozygosity for the maternal 11p15 allele, confirming that each lesion arose from independent somatic events in the setting of a paternally inherited germline ABCC8 mutation. These cases highlight the importance of a multidisciplinary and personalized approach to the management of infants with HI.

Anterior Segment Dysgenesis With Accessory Iris Membranes in an Infant With Otopalatodigital Spectrum Disorder and Mutation in the FLNA Gene

A 4-month-old male infant with frontometaphyseal dysplasia and de novo FLNA gene mutation died of complications of disease. Post-mortem examination revealed accessory iris membranes. This is the first report in the literature of accessory iris membranes in a confirmed case of FLNA mutation and phenotypic anomalies consistent with frontometaphyseal dysplasia. [J Pediatr Ophthalmol Strabismus. 2020;57:e8-e11.].

Surgical treatment of congenital hyperinsulinism: Results from 500 pancreatectomies in neonates and children

BACKGROUND

Congenital Hyperinsulinism (HI) causes severe hypoglycemia in neonates and children. We reviewed our experience with pancreatectomy for the various types of HI.

METHODS

From 1998 to 2018, 500 patients with HI underwent pancreatectomy: 246 for focal HI, 202 for diffuse HI, 37 for atypical HI (16 for Localized Islet Nuclear Enlargement [LINE], 21 for Beckwith-Wiedemann Syndrome), and 15 for insulinoma. Focal HI neonates were treated with partial pancreatectomy. Patients with diffuse HI who failed medical management underwent near-total (98%) pancreatectomy. Atypical HI patients had pancreatectomies tailored to the PET scan and biopsy findings.

RESULTS

The vast majority of pancreatectomies for focal HI were < 50%, and many were 2%-10%. 97% of focal HI patients are cured. For diffuse disease patients, 31% were euglycemic, 20% were hyperglycemic, and 49% required treatment for hypoglycemia; the incidence of diabetes increased with long-term follow-up. All 15 insulinoma patients were cured.

CONCLUSIONS

Our approach to patients with focal HI can distinguish focal from diffuse HI, localize focal lesions, and permit partial pancreatectomy with cure in almost all focal patients. Surgery does not cure diffuse disease but can help prevent severe hypoglycemia and brain damage. Surgery can be curative for insulinoma and for some cases of atypical HI.

LEVEL OF EVIDENCE

Level IV.

Diagnosis of Beckwith-Wiedemann syndrome in children presenting with Wilms tumor

Beckwith-Wiedemann syndrome (BWS) is a genetic syndrome associated with overgrowth and cancer predisposition, including predisposition to Wilms tumor (WT). Patients with BWS and BWS spectrum are screened from birth to age 7 years for BWS-associated cancers. However, in some cases a BWS-associated cancer may be the first recognized manifestation of the syndrome. We describe 12 patients diagnosed with BWS after presenting with a WT. We discuss the features of BWS in these patients and hypothesize that earlier detection of BWS by attention to its subtler manifestations could lead to earlier detection of children at risk for associated malignancies.

Cytotoxic T-Lymphocyte-Associated Protein 4 Haploinsufficiency-Associated Inflammation Can Occur Independently of T-Cell Hyperproliferation

Located contiguously on the long arm of the second chromosome are gene paralogs encoding the immunoglobulin-family co-activation receptors CD28 and cytotoxic T-lymphocyte-associated protein 4 (CTLA4). CD28 and CTLA4 share the same B7 ligands yet each provides opposing proliferative signals to T cells. Herein, we describe for the first time two unrelated subjects with coexisting CD28 and CTLA4 haploinsufficiency due to heterozygous microdeletions of chromosome 2q. Although their clinical phenotype, multi-organ inflammatory disease, is superficially similar to that of CTLA4 haploinsufficient autoimmune lymphoproliferative syndrome type V (ALPS5) patients, we demonstrate our subjects’ underlying immunopathology to be distinct. Unlike ALPS5 T cells which hyperproliferate to T-cell receptor-mediated activation and infiltrate organs, T cells from our subjects are hypoproliferative and do not. Instead of T cell infiltrates, biopsies of affected subject tissues demonstrated infiltrates of lineage negative lymphoid cells. This histologic feature correlated with significant increases in circulating type 3 innate lymphoid cells (ILC3s) and ILC3 cytokines, interleukin 22, and interleukin-17A. CTLA4-Ig monotherapy, which we trialed in one subject, was remarkably effective in controlling inflammatory diseases, normalizing ILC3 frequencies, and reducing ILC3 cytokine concentrations.

Management of adrenal masses in patients with Beckwith-Wiedemann syndrome

Beckwith-Wiedemann syndrome (BWS) is a genetic overgrowth and cancer predisposition syndrome, associated with both benign and malignant adrenal findings. Literature review and an institutional case series elucidate the wide spectrum of adrenal findings in BWS patients. The altered expression of the 11p15 region is likely related to adrenal gland hyperplasia and growth dysregulation. Given the absence of guidelines for managing adrenal findings in BWS, we propose a systematic approach to adrenal findings in BWS patients, to allow for maximum detection of potentially malignant pathology without posing additional risk to patients.

Functional and Metabolomic Consequences of KATP Channel Inactivation in Human Islets

Loss-of-function mutations of β-cell K_ATP channels cause the most severe form of congenital hyperinsulinism (K_ATPHI). K_ATPHI is characterized by fasting and protein-induced hypoglycemia that is unresponsive to medical therapy. For a better understanding of the pathophysiology of K_ATPHI, we examined cytosolic calcium ([Ca²⁺] _i ), insulin secretion, oxygen consumption, and [U-¹³C]glucose metabolism in islets isolated from the pancreases of children with K_ATPHI who required pancreatectomy. Basal [Ca²⁺] _i and insulin secretion were higher in K_ATPHI islets compared with controls. Unlike controls, insulin secretion in K_ATPHI islets increased in response to amino acids but not to glucose. K_ATPHI islets have an increased basal rate of oxygen consumption and mitochondrial mass. [U-¹³C]glucose metabolism showed a twofold increase in alanine levels and sixfold increase in ¹³C enrichment of alanine in K_ATPHI islets, suggesting increased rates of glycolysis. K_ATPHI islets also exhibited increased serine/glycine and glutamine biosynthesis. In contrast, K_ATPHI islets had low γ-aminobutyric acid (GABA) levels and lacked ¹³C incorporation into GABA in response to glucose stimulation. The expression of key genes involved in these metabolic pathways was significantly different in K_ATPHI β-cells compared with control, providing a mechanism for the observed changes. These findings demonstrate that the pathophysiology of K_ATPHI is complex, and they provide a framework for the identification of new potential therapeutic targets for this devastating condition.

Foxp3 Reprograms T Cell Metabolism to Function in Low-Glucose, High-Lactate Environments

Immune cells function in diverse metabolic environments. Tissues with low glucose and high lactate concentrations, such as the intestinal tract or ischemic tissues, frequently require immune responses to be more pro-tolerant, avoiding unwanted reactions against self-antigens or commensal bacteria. T-regulatory cells (Tregs) maintain peripheral tolerance, but how Tregs function in low-glucose, lactate-rich environments is unknown. We report that the Treg transcription factor Foxp3 reprograms T cell metabolism by suppressing Myc and glycolysis, enhancing oxidative phosphorylation, and increasing nicotinamide adenine dinucleotide oxidation. These adaptations allow Tregs a metabolic advantage in low-glucose, lactate-rich environments; they resist lactate-mediated suppression of T cell function and proliferation. This metabolic phenotype may explain how Tregs promote peripheral immune tolerance during tissue injury but also how cancer cells evade immune destruction in the tumor microenvironment. Understanding Treg metabolism may therefore lead to novel approaches for selective immune modulation in cancer and autoimmune diseases.

Phosphorylation of pRb: mechanism for RB pathway inactivation in MYCN-amplified retinoblastoma

A small, but unique subgroup of retinoblastoma has been identified with no detectable mutation in the retinoblastoma gene (RB1) and with high levels of MYCN gene amplification. This manuscript investigated alternate pathways of inactivating pRb, the encoded protein in these tumors. We analyzed the mutation status of the RB1 gene and MYCN copy number in a series of 245 unilateral retinoblastomas, and the phosphorylation status of pRb in a subset of five tumors using immunohistochemistry. There were 203 tumors with two mutations in RB1 (RB1^-/- , 83%), 29 with one (RB1^+/- , 12%) and 13 with no detectable mutations (RB1^+/+ , 5%). Eighteen tumors carried MYCN amplification between 29 and 110 copies: 12 had two (RB1^-/- ) or one RB1 (RB1^+/- ) mutations, while six had no mutations (RB1^+/+ ). Immunohistochemical staining of tumor sections with antibodies against pRb and phosphorylated Rb (ppRb) displayed high levels of pRb and ppRb in both RB1^+/+ and RB1^+/- tumors with MYCN amplification compared to no expression of these proteins in a classic RB1^-/- , MYCN-low tumor. These results establish that high MYCN amplification can be present in retinoblastoma with or without coding sequence mutations in the RB1 gene. The functional state of pRb is inferred to be inactive due to phosphorylation of pRb in the MYCN-amplified retinoblastoma without coding sequence mutations. This makes inactivation of RB1 by gene mutation or its protein product, pRb, by protein phosphorylation, a necessary condition for initiating retinoblastoma tumorigenesis, independent of MYCN amplification.

Ubiquitin-specific Protease-7 Inhibition Impairs Tip60-dependent Foxp3+ T-regulatory Cell Function and Promotes Antitumor Immunity

Foxp3 + T-regulatory (Treg) cells are known to suppress protective host immune responses to a wide variety of solid tumors, but their therapeutic targeting is largely restricted to their transient depletion or “secondary” modulation, e.g. using anti-CTLA-4 monoclonal antibody. Our ongoing studies of the post-translational modifications that regulate Foxp3 demonstrated that the histone/protein acetyltransferase, Tip60, plays a dominant role in promoting acetylation, dimerization and function in Treg cells. We now show that the ubiquitin-specific protease, Usp7, controls Treg function largely by stabilizing the expression and promoting the multimerization of Tip60 and Foxp3. Genetic or pharmacologic targeting of Usp7 impairs Foxp3 + Treg suppressive functions, while conventional T cell responses remain intact. As a result, pharmacologic inhibitors of Usp7 can limit tumor growth in immunocompetent mice, and promote the efficacy of antitumor vaccines and immune checkpoint therapy with anti-PD1 monoclonal antibody in murine models. Hence, pharmacologic therapy with Usp7 inhibitors may have an important role in future cancer immunotherapy.

•

Conditional deletion of Usp7 in Foxp3 + Treg cells causes rapidly lethal autoimmunity.

•

Pharmacologic inhibition of Usp7 impairs Treg but not conventional T cell function.

•

Usp7 targeting alone, or in conjunction with other therapies, promotes anti-tumor immunity.

T-regulatory (Treg) cells are essential to regulation of the immune system, and are characterized by their expression of the transcription factor, Foxp3. Foxp3 is subject to ubiquitination and degradation via the proteasome. We now show that the deubiquitinase, Usp7, is a key regulator of Foxp3 + Treg biology through controlling levels of the histone acetyltransferase, Tip60 and, to a lesser extent, Foxp3. Gene deletion or pharmacologic inhibition of Usp7 impairs Treg but not conventional T cell functions. The pharmacologic targeting of Usp7 alone, or in conjunction with additional therapeutic strategies, is of significant benefit in promoting host anti-tumor immunity.

Targeting Sirtuin-1 prolongs murine renal allograft survival and function

Current immunosuppressive medications used after transplantation have significant toxicities. Foxp3(+) T-regulatory cells can prevent allograft rejection without compromising protective host immunity. Interestingly, inhibiting the class III histone/protein deacetylase Sirtuin-1 can augment Foxp3(+) T-regulatory suppressive function through increasing Foxp3 acetylation. Here we determined whether Sirtuin-1 targeting can stabilize biological allograft function. BALB/c kidney allografts were transplanted into C57BL/6 recipients with a CD4-conditional deletion of Sirtuin-1 (Sirt1(fl/fl)CD4(cre)) or mice treated with a Sirtuin-1-specific inhibitor (EX-527), and the native kidneys removed. Blood chemistries and hematocrit were followed weekly. Sirt1(fl/fl)CD4(cre) recipients showed markedly longer survival and improved kidney function. Sirt1(fl/fl)CD4(cre) recipients exhibited donor-specific tolerance, accepted BALB/c, but rejected third-party C3H cardiac allografts. C57BL/6 recipients of BALB/c renal allografts that were treated with EX-527 showed improved survival and renal function at 1, but not 10 mg/kg/day. Pharmacologic inhibition of Sirtuin-1 also improved renal allograft survival and function with dosing effects having relevance to outcome. Thus, inhibiting Sirtuin-1 can be a useful asset in controlling T-cell-mediated rejection. However, effects on non-T cells that could adversely affect allograft survival and function merit consideration.

Improved renal ischemia tolerance in females influences kidney transplantation outcomes

Experimentally, females show an improved ability to recover from ischemia-reperfusion injury (IRI) compared with males; however, this sex-dependent response is less established in humans. Here, we developed a series of murine renal ischemia and transplant models to investigate sex-specific effects on recovery after IRI. We found that IRI tolerance is profoundly increased in female mice compared with that observed in male mice and discovered an intermediate phenotype after neutering of either sex. Transplantation of adult kidneys from either sex into a recipient of the opposite sex followed by ischemia at a remote time resulted in ischemia recovery that reflected the sex of the recipient, not the donor, revealing that the host sex determines recovery. Likewise, renal IRI was exacerbated in female estrogen receptor α-KO mice, while female mice receiving supplemental estrogen before ischemia were protected. We examined data from the United Network for Organ Sharing (UNOS) to determine whether there is an association between sex and delayed graft function (DGF) in patients who received deceased donor renal transplants. A multivariable logistic regression analysis determined that there was a greater association with DGF in male recipients than in female recipients. Together, our results demonstrate that sex affects renal IRI tolerance in mice and humans and indicate that estrogen administration has potential as a therapeutic intervention to clinically improve ischemia tolerance.

Histologic and Molecular Profile of Pediatric Insulinomas: Evidence of a Paternal Parent-of-Origin Effect

CONTEXT

Acquired insulinomas are rare causes of hyperinsulinemic hypoglycemia in children and are much less common than focal lesions of congenital hyperinsulinism. The latter are known to be associated with isodisomy for paternally transmitted ATP-sensitive potassium channel mutations on 11p15; however, the molecular basis for pediatric insulinomas is not well characterized.

OBJECTIVE

The purpose of this study was to characterize the histopathological and molecular defects in a large group of 12 pediatric insulinomas seen at The Children's Hospital of Philadelphia.

RESULTS

Twelve children with insulinomas were seen between 1971 and 2013, compared to 201 cases with focal congenital hyperinsulinism seen between 1997 and 2014. The age of insulinoma patients ranged from 4-16 years at the time of surgery. Features of MEN1 syndrome were present in five of the 12, including four cases with heterozygous mutations of MEN1 on 11q. Immunohistochemical analysis revealed nuclear loss of p57 staining consistent with loss of the maternal 11p15 allele in 11 of the 12 insulinomas, including all five MEN1-associated tumors. Imbalance of the paternal 11p allele was confirmed by single nucleotide polymorphism genotyping and methylation assays of the 11p imprinting control loci in four of five MEN1-associated tumors and six of seven sporadic insulinomas. In addition, single nucleotide polymorphism genotyping revealed extensive tumor aneuploidy beyond chromosome 11.

CONCLUSIONS

These data indicate that MEN1 mutations are more common in insulinomas in children than in adults. Aneuploidy of chromosome 11 and other chromosomes is common in both MEN1 and non-MEN1 insulinomas. The novel observation of a paternal parent-of-origin effect in all MEN1 and most non-MEN1 tumors suggests a critical role for imprinted growth-regulatory genes in the 11p region in the genesis of β-cell endocrine tumors in children.

Congenital hyperinsulinism in children with paternal 11p uniparental isodisomy and Beckwith-Wiedemann syndrome

BACKGROUND

Congenital hyperinsulinism (HI) can have monogenic or syndromic causes. Although HI has long been recognised to be common in children with Beckwith-Wiedemann syndrome (BWS), the underlying mechanism is not known.

METHODS

We characterised the clinical features of children with both HI and BWS/11p overgrowth spectrum, evaluated the contribution of KATP channel mutations to the molecular pathogenesis of their HI and assessed molecular pathogenesis associated with features of BWS.

RESULTS

We identified 28 children with HI and BWS/11p overgrowth from 1997 to 2014. Mosaic paternal uniparental isodisomy for chromosome 11p (pUPD11p) was noted in 26/28 cases. Most were refractory to diazoxide treatment and half required subtotal pancreatectomies. Patients displayed a wide range of clinical features from classical BWS to only mild hemihypertrophy (11p overgrowth spectrum). Four of the cases had a paternally transmitted KATP mutation and had a much more severe HI course than patients with pUPD11p alone.

CONCLUSIONS

We found that patients with pUPD11p-associated HI have a persistent and severe HI phenotype compared with transient hypoglycaemia of BWS/11p overgrowth patients caused by other aetiologies. Testing for pUPD11p should be considered in all patients with persistent congenital HI, especially for those without an identified HI gene mutation.

CD11b+Ly6G+ cells inhibit tumor growth by suppressing IL-17 production at early stages of tumorigenesis

Neutrophils are important innate immune cells involved in microbial clearance at the sites of infection. However, their role in cancer development is unclear. We hypothesized that neutrophils mediate antitumor effects in early tumorigenesis. To test this, we first studied the cytotoxic effects of neutrophils in vitro. Neutrophils were cytotoxic against tumor cells, with neutrophils isolated from tumor-bearing mice trending to have increased cytotoxic activities. We then injected an ELR+ CXC chemokine-producing tumor cell line into C57BL/6 and Cxcr2−/− mice, the latter lacking the receptors for neutrophil chemokines. We observed increased tumor growth in Cxcr2−/− mice. As expected, tumors from Cxcr2−/− mice contained fewer neutrophils. Surprisingly, these tumors also contained fewer CD8⁺ T cells, but more IL-17-producing cells. Replenishment of functional neutrophils was correlated with decreased IL-17-producing cells, increased CD8⁺ T cells, and decreased tumor size in Cxcr2−/− mice, while depletion of neutrophils in C57BL/6 mice showed the opposite effects. Results from a non-ELR+ CXC chemokine producing tumor further supported that functional neutrophils indirectly mediate tumor control by suppressing IL-17A production. We further studied the correlation of IL-17A and CD8⁺ T cells in vitro. IL-17A suppressed proliferation and IFNγ production of CD8⁺ T cells, while CD11b+Ly6G+ neutrophils did not suppress CD8⁺ T cell function. Taken together, these data demonstrate that, while neutrophils could control tumor growth by direct cytotoxic effects, the primary mechanism by which neutrophils exert antitumor effects is to regulate IL-17 production, through which they indirectly promote CD8⁺ T cell responses.

Positive Impact of Fungal Histopathology on Immunocompromised Pediatric Patients With Histology-Proven Invasive Fungal Infection

OBJECTIVES

We investigated the performance and the clinical impact of histologic examination of infected tissue in patients with suspected invasive fungal infection (IFI) at a tertiary pediatric center.

METHODS

Unique episodes of IFI were identified from January 1, 2001, through December 31, 2012. Surgical pathology reports, fungal culture results, and clinical data were abstracted from medical records.

RESULTS

Forty-seven patients with IFI were identified. Each patient had one episode of IFI. Risk factors included chemotherapy for an oncologic condition (n = 35), hematopoietic stem cell transplantation (n = 6), solid organ transplantation (n = 4), and primary immunodeficiency (n = 2). Tissue was obtained from deep subcutaneous tissue (n = 21), visceral organs (14 lungs, five livers, and one spleen), or the sinonasal cavity (n = 6). Fungal culture was ordered in 40 of the 47 episodes of IFI. Fungus grew in 27 (68%) of the 40 cultures submitted, and all isolates were concordant with histology. Medical records were available for 36 (77%) of 47 patients. Communication of histology results prompted changes in antifungal therapy 64% of the time. This included initiation of antifungal therapy in 13 patients who were not previously receiving therapy. Fifteen (42%) patients underwent surgical excision within 48 hours of histologic diagnosis.

CONCLUSIONS

Histology can provide rapid, accurate, and clinically actionable information to clinicians caring for children with IFI.

Essential role of mitochondrial energy metabolism in Foxp3⁺ T-regulatory cell function and allograft survival

Conventional T (Tcon) cells and Foxp3(+) T-regulatory (Treg) cells are thought to have differing metabolic requirements, but little is known of mitochondrial functions within these cell populations in vivo. In murine studies, we found that activation of both Tcon and Treg cells led to myocyte enhancer factor 2 (Mef2)-induced expression of genes important to oxidative phosphorylation (OXPHOS). Inhibition of OXPHOS impaired both Tcon and Treg cell function compared to wild-type cells but disproportionally affected Treg cells. Deletion of Pgc1α or Sirt3, which are key regulators of OXPHOS, abrogated Treg-dependent suppressive function and impaired allograft survival. Mef2 is inhibited by histone/protein deacetylase-9 (Hdac9), and Hdac9 deletion increased Treg suppressive function. Hdac9(-/-) Treg showed increased expression of Pgc1α and Sirt3, and improved mitochondrial respiration, compared to wild-type Treg cells. Our data show that key OXPHOS regulators are required for optimal Treg function and Treg-dependent allograft acceptance. These findings provide a novel approach to increase Treg function and give insights into the fundamental mechanisms by which mitochondrial energy metabolism regulates immune cell functions in vivo.

The type 2 diabetes associated rs7903146 T allele within TCF7L2 is significantly under-represented in Hereditary Multiple Exostoses: insights into pathogenesis

Hereditary Multiple Exostoses (HME) is an autosomal-dominant disorder characterized by benign cartilage tumors (exostoses) forming near the growth plates, leading to severe health problems. EXT1 and EXT2 are the two genes known to harbor heterozygous loss-of-function mutations that account for the vast majority of the primary genetic component of HME. However, patients present with wide clinical heterogeneity, suggesting that modifier genes play a role in determining severity. Our previous work has pointed to an imbalance of β-catenin signaling being involved in the pathogenesis of osteochondroma formation. TCF7L2 is one of the key 'gate-keeper' TCF family members for Wnt/β-catenin signaling pathway, and TCF7L2 and EXT2 are among the earliest associated loci reported in genome wide appraisals of type 2 diabetes (T2D). Thus we investigated if the key T allele of single nucleotide polymorphism (SNP) rs7903146 within the TCF7L2 locus, which is strongly over-represented among T2D cases, was also associated with HME. We leveraged genotype data available from ongoing GWAS efforts from genomics and orthopedic centers in the US, Canada and Italy. Collectively 213 cases and 1890 controls were analyzed and, surprisingly, the T allele was in fact significantly under-represented in the HME patient group [P = 0.009; odds ratio = 0.737 (95% C.I. 0.587-0.926)]; in addition, the direction of effect was consistent within each individual cohort. Immunohistochemical analyses revealed that TCF7L2 is differentially expressed and distributed in normal human growth plate zones, and exhibits substantial variability in human exostoses in terms of staining intensity and distribution. In summary, the data indicate that there is a putative genetic connection between TCF7L2 and EXT in the context of HME. Given this observation, we suggest that these loci could possibly modulate shared pathways, in particular with respect to β-catenin, and their respective variants interplay to influence HME pathogenesis as well as T2D.

FOXP3+ regulatory T cell development and function require histone/protein deacetylase 3

Treg dysfunction is associated with a variety of inflammatory diseases. Treg populations are defined by expression of the oligomeric transcription factor FOXP3 and inability to produce IL-2, a cytokine required for T cell maintenance and survival. FOXP3 activity is regulated post-translationally by histone/protein acetyltransferases and histone/protein deacetylases (HDACs). Here, we determined that HDAC3 mediates both the development and function of the two main Treg subsets, thymus-derived Tregs and induced Tregs (iTregs). We determined that HDAC3 and FOXP3 physically interact and that HDAC3 expression markedly reduces Il2 promoter activity. In murine models, conditional deletion of Hdac3 during thymic Treg development restored Treg production of IL-2 and blocked the suppressive function of Tregs. HDAC3-deficient mice died from autoimmunity by 4-6 weeks of age; however, injection of WT FOXP3+ Tregs prolonged survival. Adoptive transfer of Hdac3-deficient Tregs, unlike WT Tregs, did not control T cell proliferation in naive mice and did not prevent allograft rejection or colitis. HDAC3 also regulated the development of iTregs, as HDAC3-deficient conventional T cells were not converted into iTregs under polarizing conditions and produced large amounts of IL-2, IL-6, and IL-17. We conclude that HDAC3 is essential for the normal development and suppressive functions of thymic and peripheral FOXP3+ Tregs.

The inflammatory phenotype of the fibrous plate is distinct from the liver and correlates with clinical outcome in biliary atresia

Biliary atresia is an inflammatory cholangiopathy of still undetermined etiology. Correlations between histologic findings and clinical outcome in this disease have largely been based on evaluation of liver parenchyma. This study aimed to characterize the pattern of inflammation within the biliary remnant and identify associations between the type and degree of inflammation and clinical outcome as reflected by the transplant-free interval. The inflammation within the fibrous plates and livers of 41 patients with biliary atresia was characterized using immunohistochemical markers and the cell populations were digitally quantified. The type and quantity of cells within the infiltrate were then correlated with length of time from Kasai portoenterostomy until transplant. Histologic and immunohistochemical features of the biliary remnant allowed stratification of patients into "inflammatory plate" and "fibrotic plate" groups. Overall there was no significant difference in transplant-free interval between the two cohorts; however, there was a trend towards a longer time to transplant among patients in the "fibrotic plate" group. In addition, the composition of the inflammatory infiltrate in the fibrous plate was distinctly different from that present in the liver and only the characteristics of the inflammation in the fibrous plate, in particular the number of Foxp3+ T regulatory lymphocytes correlated with clinical outcome. The results of this study support the view of the extra-hepatic biliary tree as the primary site of injury in BA with the changes seen in the liver as secondary manifestations of outflow obstruction. The association between specific inflammatory cell subtypes within the fibrous plate and the length of transplant-free interval also supports the role of the immune system in the initial process of bile duct damage in biliary atresia.

Angiolymphoid hyperplasia with eosinophilia: a previously unreported complication of ear piercing

Angiolymphoid hyperplasia with eosinophilia is a rare, benign vascular lesion characterized by discrete, painful papules. Although the exact etiology is unknown, trauma precedes many cases. We present a case of angiolymphoid hyperplasia with eosinophilia in the earlobes of a 15-year-old girl after ear piercing.

Heat shock protein 70 is required for optimal liver regeneration after partial hepatectomy in mice

Liver regeneration is a complex process that restores functional tissue after resection or injury, and it is accompanied by transient adenosine triphosphate depletion and metabolic stress in hepatic parenchymal cells. Heat shock protein 70 (Hsp70) functions as a chaperone during periods of cellular stress and induces the expression of several inflammatory cytokines identified as key players during early liver regeneration. We, therefore, hypothesized that Hsp70 is required for the initiation of regeneration. Investigations were carried out in a 70% partial hepatectomy mouse model with mice lacking inducible Hsp70 (Hsp70(-/-)). Liver regeneration was assessed postoperatively with the liver weight/body weight (LW/BW) ratio, and sera and tissues were collected for analysis. In addition, the expression of Hsp-related genes was assessed in a cohort of 23 human living donor liver transplantation donors. In mice, the absence of Hsp70 was associated with a reduced postoperative LW/BW ratio, Ki-67 staining, and tumor necrosis factor α (TNF-α) expression in comparison with wild-type mice. TNF-α expression was also reduced in livers from Hsp70(-/-) mice after induction with lipopolysaccharide (1 mg/kg). Clinically, the transcription of multiple Hsp genes (especially Hsp70 family members) was up-regulated after donor hepatectomy. Together, these results suggest that the early phase of successful liver regeneration requires the presence of Hsp70 to induce TNF-α. Further studies are required to determine whether Hsp70 contributes to liver regeneration as a chaperone by stabilizing specific interactions required for growth signaling or as a paracrine inflammatory signal, as can occur in models of shock.

The surgical management of insulinomas in children

PURPOSE

Insulinomas are rare pediatric tumors for which optimal localization studies and management remain undetermined. We present our experience with surgical management of insulinomas during childhood.

METHODS

A retrospective review was performed of patients who underwent surgical management for an insulinoma from 1999 to 2012.

RESULTS

The study included eight patients. Preoperative localization was successful with abdominal ultrasound, abdominal CT, endoscopic ultrasound, or MRI in only 20%, 28.6%, 40%, and 50% of patients, respectively. Octreotide scan was non-diagnostic in 4 patients. For diagnostic failure, selective utilization of 18-Fluoro-DOPA PET/CT scanning, arterial stimulation/venous sampling, or transhepatic portal venous sampling were successful in insulinoma localization. Intraoperatively, all lesions were identified by palpation or with the assistance of intraoperative ultrasound. Surgical resection using pancreas sparing techniques (enucleation or distal pancreatectomy) resulted in a cure in all patients. Postoperative complications included a pancreatic fistula in two patients and an additional missed insulinoma in a patient with MEN-1 requiring successful reoperation.

CONCLUSIONS

Preoperative tumor localization may require many imaging modalities to avoid unsuccessful blind pancreatectomy. Intraoperative palpation with the assistance of ultrasound offers a reliable method to precisely locate the insulinoma. Complete surgical resection results in a cure. Recurrent symptoms warrant evaluation for additional lesions.

Pancreatic surgery in infants with Beckwith-Wiedemann syndrome and hyperinsulinism

PURPOSE

To present our experience in the care of infants with Beckwith-Wiedemann syndrome (BWS) who required pancreatectomy for the management of severe Congenital Hyperinsulinism (HI).

METHODS

We did a retrospective chart review of patients with BWS who underwent pancreatectomy between 2009 and 2012.

RESULTS

Four patients with BWS and severe HI underwent pancreatectomy, 3 females and one male. Eight other BWS patients with HI could be managed medically. The diagnosis of BWS was established by the presence of mosaic 11p15 loss of heterozygosity and uniparental disomy in peripheral blood and/or pancreatic tissue. All patients had hypoglycemia since birth that did not respond to medical management with diazoxide or octreotide, and required glucose infusion rates of up to 30 mg/kg/min. Preoperative 18-F-DOPA PET/CT scans showed diffuse uptake of the radiotracer throughout an enlarged pancreas in three patients and a normal sized pancreas with a large area of focal uptake in the pancreatic body in one patient. None of the patients had mutations in the ABCC8 or KCNJ1 genes that are typically associated with diazoxide-resistant HI. Age at surgery was 1, 2, 4, and 12 months and the procedures were 85%, 95%, 90%, and 75% pancreatectomy, respectively, with the pancreatectomy extent tailored to HI severity. Pathologic analysis revealed marked diffuse endocrine proliferation throughout the pancreas that occupied up to 80% of the parenchyma with scattered islet cell nucleomegaly. One patient had a small pancreatoblastoma in the pancreatectomy specimen. The HI improved in all cases after the pancreatectomy, with patients being able to fast safely for more than 8 h. All patients are under close surveillance for embryonal tumors. One patient developed a hepatoblastoma at age 2.

CONCLUSION

The pathophysiology of HI in BWS patients is likely multifactorial and is associated with a dramatic increase in pancreatic endocrine tissue. Severe cases of HI that do not respond to medical therapy improve when the mass of endocrine tissue is reduced by subtotal or near-total pancreatectomy.

Clinical features of three girls with mosaic genome-wide paternal uniparental isodisomy

Here we describe three subjects with mosaic genome-wide paternal uniparental isodisomy (GWpUPD) each of whom presented initially with overgrowth, hemihyperplasia (HH), and hyperinsulinism (HI). Due to the severity of findings and the presence of additional features, SNP array testing was performed, which demonstrated mosaic GWpUPD. Comparing these individuals to 10 other live-born subjects reported in the literature, the predominant phenotype is that of pUPD11 and notable for a very high incidence of tumor development. Our subjects developed non-metastatic tumors of the adrenal gland, kidney, and/or liver. All three subjects had pancreatic hyperplasia resulting in HI. Notably, our subjects to date display minimal features of other diseases associated with paternal UPD loci. Both children who survived the neonatal period have displayed near-normal cognitive development, likely due to a favorable tissue distribution of the mosaicism. To understand the range of UPD mosaicism levels, we studied multiple tissues using SNP array analysis and detected levels of 5-95%, roughly correlating with the extent of tissue involvement. Given the rapidity of tumor growth and the difficulty distinguishing malignant and benign tumors in these GWpUPD subjects, we have utilized increased frequency of ultrasound (US) and alpha-fetoprotein (AFP) screening in the first years of life. Because of a later age of onset of additional tumors, continued tumor surveillance into adolescence may need to be considered in these rare patients.

Bilateral pheochromocytomas, hemihyperplasia, and subtle somatic mosaicism: the importance of detecting low-level uniparental disomy

We report on a patient with early onset pediatric bilateral pheochromocytomas caused by mosaic chromosome 11p15 paternal uniparental isodisomy (UPD). Hemihyperplasia of the arm was diagnosed in a 4-month-old female and clinical methylation testing for 11p15 in the blood was normal, with a reported detection threshold for mosaicism of 20%. She was subsequently diagnosed at 18 months with bilateral pheochromocytomas. Single-nucleotide polymorphism (SNP) array analysis of pheochromocytoma tissue demonstrated mosaic deletions of 8p12pter, 21q21.1qter, 22q11.23qter; commonly seen in pheochromocytomas. In addition, mosaic 11p15.3pter homozygosity was noted. Molecular testing for other causes of pheochromocytomas was normal, suggesting that 11p15 homozygosity was the primary event. Subsequent SNP array analysis of skin fibroblasts from the hyperplastic side demonstrated 5% mosaic paternal UPD for 11p15. We have subsequently used SNP array analysis to identify four patients with subtle hemihyperplasia with low-level mosaic UPD that was not detected by methylation analysis. Given the increased sensitivity of SNP array analysis to detect UPD along with the increased incidence of tumorigenesis in these UPD patients, we suggest that it has high utility in the clinical work-up of hemihyperplasia. The present case also suggests that 11p15 paternal UPD may be an under-detected mechanism of sporadic pheochromocytoma in the pediatric population. Furthermore, a review of the literature suggests that patients with 11p15 paternal UPD may present after 8 years of age with pheochromocytoma and raises the possibility that ultrasound screening could be considered beyond 8 years of age in this subset of hemihyperplasia and Beckwith-Wiedemann syndrome patients.

Lymphocytic gastritis in pediatric celiac disease

An increase in gastric intraepithelial lymphocytes has been observed in some patients with the typical small intestinal changes of celiac disease. To date, no clinical parameters have been described that identify the subset of patients more likely to have gastric involvement. In this study we compared the clinical features of celiac disease patients with and without lymphocytic gastritis to determine if the presence of gastric involvement at diagnosis portends a more severe form of celiac disease. We reviewed the pathology reports and hematoxylin and eosin-stained slides of 304 patients with biopsy-proven celiac disease diagnosed over an 11-year period. Thirty-nine of these patients had lymphocytic gastritis. Compared to patients without gastric involvement, those with lymphocytic gastritis were statistically more likely to be diagnosed at an earlier age and present with more profound laboratory findings and duodenal mucosal damage compared to patients with celiac disease without gastric involvement. These findings indicate that in the pediatric population, the presence of lymphocytic gastritis in celiac disease defines a unique group of patients with more severe disease (by clinical and laboratory measures) at the time of diagnosis.

Descriptive epidemiology of infantile cataracts in metropolitan Atlanta, GA, 1968-1998

BACKGROUND

Infantile cataract is an important cause of childhood visual impairment. Surgery before 6 weeks of age is recommended for optimal visual outcome. Description of the epidemiologic characteristics of cataracts is important for an improved understanding of the condition.

OBJECTIVES

To identify at-risk populations and facilitate successful treatment of patients with infantile cataracts.

METHODS

Infants with cataracts diagnosed in the first year of life were identified using the Metropolitan Atlanta Congenital Defects Program, a birth defects surveillance program with active methods of case ascertainment, for the years 1968-1998. Several factors were analyzed, including year of birth, sex, race, maternal age, plurality (single vs multiple gestation), gestational age, birth weight, laterality, seasonality, and age at diagnosis.

RESULTS

A total of 199 infants with cataracts were identified, for a rate of 2.03 per 10 000 births. In 117 infants (59%), cataracts occurred as an isolated defect; in 43 infants (22%), cataracts occurred as part of a syndrome; and in 39 infants (20%), additional, unrelated, major birth defects were also present. Rates were higher for low-birth-weight infants (those weighing <1500 g; risk ratio [RR], 6.01; 95% confidence interval [CI], 3.83-9.43) and preterm infants (RR, 1.70; 95% CI, 1.21-2.40). Of the cases that occurred as an isolated defect, 38% were diagnosed after 6 weeks.

CONCLUSIONS

This population-based study provides 31 years of data from a diverse US population and allows identification of risk factors for infantile cataracts. The finding that a number of infants with cataracts continue to have their conditions diagnosed after 6 weeks of age emphasizes the need for direct ophthalmoscopic examination of the red reflex in the newborn period to facilitate early detection and improve outcomes.