Diffuse large B-cell lymphoma (DLBCL) is one of the most prevalent haematological malignancies in both humans and dogs, characterised in both species by significant clinical heterogeneity and limited prognostic predictability. With the introduction of next-generation sequencing (NGS) technologies in veterinary medicine over the past decade, researchers have begun to elucidate the molecular basis of canine DLBCL (cDLBCL); however, much of the clinical heterogeneity associated with this tumour remains unexplained. In this study, we performed whole genome sequencing on 10 cDLBCL cases, all treated with chemo-immunotherapy, which exhibited similar clinico-pathological features but markedly different outcomes. Cases were classified as "poor" or "good" responders based on whether their lymphoma-specific survival fell below or above the cohort's median. Protein-coding variants and copy number aberrations unique to poor or good responders revealed novel candidate genes not previously identified in cDLBCL studies, while splicing, untranslated regions, and intronic variants were detected in genes already known to be recurrently mutated. In conclusion, our investigation has broadened the spectrum of potentially pathogenic variants implicated in cDLBCL, though further studies with larger cohorts are necessary to validate these findings.

Abstract We developed a targeted next-generation sequencing approach designed for the genomic classification of canine lymphoma. Positioned within the evolving landscape of comparative and veterinary oncology, this study underscores the clinical significance of tailored genetic profiling for this tumor in dogs, marking a crucial step in diagnostic high-throughput genetic analysis. Leveraging a previous dataset, the “K9 lymphoma assay” demonstrated robust comparability and reproducibility in canine diffuse large B-cell lymphoma (DLBCL), when matched with previously tumors examined through whole-exome sequencing. Expanding our investigation to encompass several B- and T-cell lymphoma histotypes, we unveiled distinct mutational landscapes distinguishing nodal lymphomas derived from immature lymphocytes and nodal lymphomas originating from mature lymphocytes. TRAF3 was the most frequently altered gene in B-cell lymphomas, exhibiting unique mutational patterns. Key genetic events, such as TP53 and SETD2 mutations, clinically demonstrated universal implications across B-cell lymphomas, positioning them as potential prognostic and therapeutic indicators. These findings advocate for a tailored therapeutic approach directly impacting treatment decisions and outcomes in managing canine lymphomas. Our study provides the largest and most comprehensive genomic characterization of clinically staged canine lymphomas to date, and it provides pivotal insights for future research and therapeutic strategies in comparative oncology.

We present here the K9 lymphoma assay, a novel 31-gene targeted next-generation sequencing panel designed for genomic profiling of canine lymphoid neoplasms. Addressing the growing demand for advanced diagnostics in veterinary oncology, this assay enables sensitive identification of known and actionable mutations specific to canine lymphomas, while evaluating its prognostic potential to facilitate diagnosis and prognosis. Our analysis, spanning several B- and T-cell lymphoma histotypes, unveiled distinct mutational landscapes distinguishing tumors derived from immature versus mature lymphocytes. Clustering analysis revealed a shared genetic origin between diffuse large B-cell lymphoma and marginal zone lymphoma, aligning with findings in human lymphomas, with TRAF3 emerging as the most frequently mutated gene across B-cell lymphoma subtypes. Significantly, TP53 mutations demonstrated universal adverse prognostic implications across B-cell lymphomas. Additionally, SETD2 mutations contributed to shorter time-to-progression, underscoring the role of epigenetic dysregulation in B-cell tumors. In T-cell lymphomas, SATB1 and FBXW7 were frequently mutated, warranting further investigation in larger cohorts. Our findings advocate for tailored therapeutic approaches based on the genetic profile, impacting treatment decisions and outcomes in canine lymphoma management. This study provides pivotal insights bridging veterinary and human oncology, paving the way for comprehensive genomic diagnostics and therapeutic strategies in comparative oncology.

TP53 mutations are associated with short survival and poor treatment response in canine diffuse large B-cell lymphoma (cDLBCL). The expression of TP53 by RNAscope® in situ hybridization and p53 by immunohistochemistry (IHC) was investigated in 37 formalin-fixed paraffin-embedded cDLBCL, to assess their correlation with TP53 mutational status and to evaluate their prognostic value. TP53 was detected in all samples by RNAscope®. Ten of 37 (27%) cases expressed p53 by IHC, with highly variable percentage of positive cells. TP53 RNAscope® scores and p53 IHC results were not correlated. The expression of TP53 by RNAscope® was not influenced by its mutational status. Conversely, p53 IHC and TP53 mutations were significantly associated. p53 IHC predicted TP53 genetic mutations with high accuracy (97.3%). All TP53-mutated samples carrying missense mutations exhibited p53 expression by IHC, while all wild-type cases and a single case with frameshift insertion were negative. In univariable analysis, p53 IHC was associated with shorter time to progression (TTP) and lymphoma-specific survival (LSS). Nevertheless, in multivariable analysis, only treatment significantly affected TTP and LSS. These findings suggest p53 IHC is an accurate, cost-effective tool for predicting TP53 mutations in cDLBCL, unlike TP53 RNAscope®, though its prognostic value requires further validation.

The Canine Cancer Genome Atlas (https://caninecancergenomeatlas.org/) represents a groundbreaking advance in comparative oncology, offering an unprecedented wealth of genetic data across ten canine cancer types. This invaluable resource, encompassing 770 cases, reveals over 34,000 genetic variants, providing a comprehensive map of canine cancer genetics. By bridging the gap between canine and human oncology, the Canine Cancer Genome Atlas (CCGA) reveals shared oncogenic pathways and potential therapeutic targets. Key findings parallel human cancer genetics, with mutations in TP53, PIK3CA, and PTEN emerging as prominent features. The atlas also elucidates copy number alterations and mutational signatures associated with DNA repair deficiencies and carcinogen exposure. Through its user-friendly web platform, the CCGA equips researchers with state-of-the-art visualization and analysis tools, fostering collaboration and accelerating scientific discoveries. As the CCGA expands to incorporate multi-omics data, it promises to deepen understanding of cancer's molecular complexities. This indispensable resource not only advances veterinary oncology but also holds the potential to transform human cancer treatment, exemplifying the profound impact of comparative genomics in the battle against cancer.

Several molecular clonality assays have been developed to assess canine B cell proliferations. These assays were based on different sequence data, utilized different assay designs and employed different testing strategies. This has resulted in a complex body of literature and complicates evidence-based selection of primer sets. In addition, further refinement of primer sets is difficult because it is unknown how well current primer sets cover the expressed sequence repertoire. The objectives of this study were 1) to provide an overview of published IGH clonality assays that highlights key differences in assay design and testing strategy and 2) to propose a novel method for optimizing primer sets that leverages large-scale sequencing data. A review of previously published assays highlighted confounding factors that hamper a direct comparison of performance metrics between studies. These findings illustrate the need for a multi-institutional effort to harmonize veterinary clonality testing. A novel in silico analysis of primer sequences using a large dataset of expressed sequences identified shortfalls of existing primer sets and was used to guide primer optimization. Three optimized primer sets were tested and yielded qualitative sensitivity values between 80–90%. The qualitative sensitivity ranged from 1% to over 50% and was dependent on the size of the neoplastic clone and the sample DNA used. These findings illustrate that inclusion of high-throughput sequencing data for primer design can be a useful tool to guide primer design and optimization. This strategy could be applied to other antigen receptor loci or species to further improve veterinary clonality assays.

Canine diffuse large B-cell lymphoma (cDLBCL) is characterized by high mortality and clinical heterogeneity. Although chemo-immunotherapy improves outcome, treatment response remains mainly unpredictable. To identify a set of immune-related genes aberrantly regulated and impacting the prognosis, we explored the immune landscape of cDLBCL by NanoString. The immune gene expression profile of 48 fully clinically characterized cDLBCLs treated with chemo-immunotherapy was analyzed with the NanoString nCounter Canine IO Panel using RNA extracted from tumor tissue paraffin blocks. A Cox proportional-hazards model was used to design a prognostic gene signature. The Cox model identified a 6-gene signature ( IL2RB, BCL6, TXK, C2, CDKN2B, ITK) strongly associated with lymphoma-specific survival, from which a risk score was calculated. Dogs were assigned to high-risk or low-risk groups according to the median score. Thirty-nine genes were differentially expressed between the 2 groups. Gene set analysis highlighted an upregulation of genes involved in complement activation, cytotoxicity, and antigen processing in low-risk dogs compared with high-risk dogs, whereas genes associated with cell cycle were downregulated in dogs with a lower risk. In line with these results, cell type profiling suggested the abundance of natural killer and CD8+ cells in low-risk dogs compared with high-risk dogs. Furthermore, the prognostic power of the risk score was validated in an independent cohort of cDLBCL. In conclusion, the 6-gene-derived risk score represents a robust biomarker in predicting the prognosis in cDLBCL. Moreover, our results suggest that enhanced tumor antigen recognition and cytotoxic activity are crucial in achieving a more effective response to chemo-immunotherapy.

Passive immunotherapy with monoclonal antibodies has improved outcome for patients with B-cell malignancies, although many still relapse and little progress has been made with T-cell malignancies. Novel treatment approaches are clearly required in this disease setting. There has been much recent interest in developing therapeutic approaches to enhance antitumor immune responses using novel immunomodulatory agents in combination with standard of care treatments. Here we report that intravenous administration of the Toll-like receptor 7 (TLR7) agonist, R848 in combination with radiation therapy (RT), leads to the longstanding clearance of tumor in T- and B-cell lymphoma bearing mice. In combination, TLR7/RT therapy leads to the expansion of tumor antigen-specific CD8+ T cells and improved survival. Furthermore, those mice that achieve long-term clearance of tumor after TLR7/RT therapy are protected from subsequent tumor rechallenge by the generation of a tumor-specific memory immune response. Our findings demonstrate the potential for enhancing the efficacy of conventional cytotoxic anticancer therapy through combination with a systemically administered TLR7 agonist to improve antitumor immune responses and provide durable remissions.

Diffuse large B-cell lymphoma (DLBCL) is the most common hematological malignancy in humans and dogs. Several studies disclosed some similarities between the two species, including the constitutive activation of the NF-κB pathway as a fundamental underlying pathogenetic mechanism. In humans, the downregulation of IL-1R8 is implicated in DLBCL development, but its role in dogs has not been explored so far. To gain insight into the pathogenesis of this tumor in dogs, we evaluated the mRNA and protein expression of IL-1R8 in 12 control lymph nodes obtained from dogs not bearing tumors and from 50 dogs with DLBCL. Moreover, we analyzed through qRT-PCR the expression of TLR7, TLR9, MYC, and p52 genes that are known to be involved in the IL-1R8 regulatory network. IL-1R8 and p52 were downregulated in DLBCLs compared to control lymph nodes (p < 0.001), while a higher expression of TLR7, TLR9, and MYC was observed in DLBCLs (p < 0.01). Immunohistochemistry confirmed the gene expression results, revealing a significantly lower IL-1R8 staining score in DLBCLs compared to control lymph nodes (p < 0.0001). Taken together, these results suggest that IL-1R8 downregulation may represent one of the mechanisms driving DLBCL pathogenesis in dogs, mainly through the dysregulation of the Toll-like/interleukin receptors signaling cascade and the aberrant activation of the classical NF-κB pathway.

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoid neoplasm in dogs and in humans. It is characterized by a remarkable degree of clinical heterogeneity that is not completely elucidated by molecular data. This poses a major barrier to understanding the disease and its response to therapy, or when treating dogs with DLBCL within clinical trials. We performed an integrated analysis of exome ( n = 77) and RNA sequencing ( n = 43) data in a cohort of canine DLBCL to define the genetic landscape of this tumor. A wide range of signaling pathways and cellular processes were found in common with human DLBCL, but the frequencies of the most recurrently mutated genes ( TRAF3 , SETD2 , POT1 , TP53 , MYC , FBXW7 , DDX3X and TBL1XR1 ) differed. We developed a prognostic model integrating exonic variants and clinical and transcriptomic features to predict the outcome in dogs with DLBCL. These results comprehensively define the genetic drivers of canine DLBCL and can be prospectively utilized to identify new therapeutic opportunities.

AbstractBackgroundSHOX enhancer CNVs, affecting one or more of the seven recognized evolutionary conserved non‐coding elements (CNEs) represent one of the most frequent cause of SHOX‐haploinsufficiency. During the diagnostic workflow deletions/duplications have been identified downstream SHOX not including any of the these CNEs.MethodsFine tiling aCGH and breakpoint PCR were used to characterize the critical interval and to search for novel alterations in a cohort of selected patients.ResultsScreening of 252 controls provided evidence that duplications in this area represent likely benign variants whereas none of the deletions were detected. These findings suggested that other alterations relevant for SHOX‐haploinsufficiency might be missed by the standard diagnostic methods. To identify such undisclosed elements, the aCGH was used to reanalyze 52 unresolved cases with clinical features strongly suggestive of SHOX‐haploinsufficiency. This analysis followed by the screening of 210 patients detected two partially overlapping small deletions of ~12 and ~8 kb in four unrelated individuals, approximately 15 kb downstream SHOX, that were absent in 720 normal stature individuals.ConclusionOur results strengthen the hypothesis that alterations of yet unidentified cis‐regulatory elements residing outside those investigated through conventional methods, might explain the phenotype in ISS/LWD patients thus enlarging the spectrum of variants contributing to SHOX‐haploinsufficiency.

Canine apocrine gland anal sac adenocarcinoma (AGASACA) is an aggressive canine tumor originating from the anal sac glands. Surgical resection, with or without adjuvant chemotherapy, represents the standard of care for this tumor, but the outcome is generally poor, particularly for tumors diagnosed at an advanced stage. For this reason, novel treatment options are warranted, and a few recent reports have suggested the activation of the immune checkpoint axis in canine AGASACA. In our study, we developed canine-specific monoclonal antibodies targeting PD-1 and PD-L1. A total of 41 AGASACAs with complete clinical and follow-up information were then analyzed by immunohistochemistry for the expression of the two checkpoint molecules (PD-L1 and PD-1) and the presence of tumor-infiltrating lymphocytes (CD3 and CD20), which were evaluated within the tumor bulk (intratumor) and in the surrounding stroma (peritumor). Seventeen AGASACAs (42%) expressed PD-L1 in a range between 5% and 95%. The intratumor lymphocytes were predominantly CD3+ T-cells and were positively correlated with the number of PD-1+ intratumor lymphocytes (ρ = 0.36; p = 0.02). The peritumor lymphocytes were a mixture of CD3+ and CD20+ cells with variable PD-1 expression (range 0–50%). PD-L1 expression negatively affected survival only in the subgroup of dogs treated with surgery alone (n = 14; 576 vs. 235 days). The presence of a heterogeneous lymphocytic infiltrate and the expression of PD-1 and PD-L1 molecules support the relevance of the immune microenvironment in canine AGASACAs and the potential value of immune checkpoints as promising therapeutic targets.

Glucocorticoids are often used illegally in food-producing animals for the growth promotion of livestock animals. In accordance to official chemical methods for glucocorticoid detection, an animal is declared as non-compliant when a residue is identified in the sample. Neverthless, growth promoting molecules can often escape identification due to their rapid elimination or due to the use of non-detectable new generation drugs. Therefore, an indirect screening method able to detect the biological effect of long-term administration of low doses of dexamethasone and prednisolone on livestock has been developed to support official methods. As already described, FKBP5 (FKBP prolyl isomerase 5) expression in bovine thymus is regulated by glucocorticoids, and this specific regulation can be exploited in an indirect screening assay. In the present study, male veal calves and young bulls were considered in three different trials in which estradiol, dexamethasone, and prednisolone were administered alone or in combination with Revalor-200 subcutaneous pellets. Thoracic thymus was sampled from all animals and molecular analysis was performed. A duplex droplet digital PCR assay with EvaGreen® was employed to detect the target gene expression using absolute quantification. The developed droplet digital PCR assay was precise, showing intra- and inter-assay mean coefficient of variation values of about 6.16% and 3.17%, respectively. It was also highly specific (100%) with Youden's index of 76.92% and 53.57% applied to veal calves and young bulls, respectively. The lowest detection limit in which the target gene expression level was kept constant, was 0.05 ng/μl of cDNA with 1 copies/μL and 0.5 copies/μL for target and reference gene, respectively. This study establishes the basis for using a digital PCR-based assay as an efficient test to identify animals illegally treated with glucocorticoids.

Diffuse large B-cell lymphoma (DLBCL) represents one of the most frequent and deadliest neoplasia in dogs worldwide and is characterized by a remarkable degree of clinical heterogeneity, with poor chances to anticipate the outcome. Even if in the last years some recurrently mutated genes have been identified, the genetic origin of canine DLBCL (cDLBCL) is not yet completely understood. The aim of the present study was to assess the prevalence of POT1 mutations in cDLBCL and to elucidate the role of such gene in the pathogenesis of this tumor. Mutations in POT1 were retrieved in 34% of cases, in line with previous reports, but no significant associations with any clinico-pathological variable were identified. Likewise, POT1 mutations are not predictive of worse prognosis. Interestingly, Ki-67 index was significantly higher in dogs harboring POT1 mutations compared to wild-type ones. These results suggest that POT1 mutations may exert their pathogenic role in cDLBCL by promoting cellular proliferation.

In dogs, Burkitt-like lymphoma (B-LL) is rare tumor and it is classified as a high-grade B-cell malignancy. The diagnosis is challenging because of the similar histologic appearance with other histotypes, no defined phenotypical criteria and poorly described clinical aspects. The aim of the study was to provide a detailed description of clinical and morphological features, as well as immunophenotypical profile of B-LL in comparison with the human counterpart. Thirteen dogs with histologically proven B-LL, for which a complete staging and follow-up were available, were retrospectively selected. Immunohistochemical expression of CD20, PAX5, CD3, CD10, BCL2, BCL6, MYC, and caspase-3 was evaluated. Histologically, all B-LLs showed a diffuse architecture with medium to large-sized cells, high mitotic rate and diffuse starry sky appearance. B-phenotype of neoplastic cells was confirmed both by flow-cytometry and immunohistochemistry. Conversely, B-LLs were negative for BCL2 and MYC, whereas some cases co-expressed BCL6 and CD10, suggesting a germinal center B-cell origin. Disease stage was advanced in the majority of cases. All dogs received CHOP-based chemotherapy with or without immunotherapy. Despite treatment, prognosis was poor, with a median time to progression and survival of 130 and 228 days, respectively. Nevertheless, ~30% of dogs survived more than 1 year. An increased apoptotic index, a high turnover index and caspase-3 index correlated with shorter survival. In conclusion, canine B-LL shows phenotypical differences with the human counterpart along with features that might help to differentiate this entity from diffuse large B-cell lymphoma.

Immune checkpoints are a set of molecules dysregulated in several human and canine cancers and aberrations of the PD-1/PD-L1 axis are often correlated with a worse prognosis. To gain an insight into the role of immune checkpoints in canine diffuse large B-cell lymphoma (cDLBCL), we investigated PD-L1, PD-1 and CD8A expression by RNAscope. Results were correlated with several clinico-pathological features, including treatment, Ki67 index and outcome. A total of 33 dogs treated with chemotherapy (n = 12) or chemoimmunotherapy with APAVAC (n = 21) were included. PD-L1 signal was diffusely distributed among neoplastic cells, whereas PD-1 and CD8A were localized in tumor infiltrating lymphocytes. However, PD-1 mRNA was also retrieved in tumor cells. An association between PD-L1 and PD-1 scores was identified and a higher risk of relapse and lymphoma-related death was found in dogs treated with chemotherapy alone and dogs with higher PD-L1 and PD-1 scores. The correlation between PD-L1 and PD-1 is in line with the mechanism of immune checkpoints in cancers, where neoplastic cells overexpress PD-L1 that, in turn, binds PD-1 receptors in activated TIL. We also found that Ki67 index was significantly increased in dogs with the highest PD-L1 and PD-1 scores, indirectly suggesting a role in promoting tumor proliferation. Finally, even if the biological consequence of PD-1+ tumor cells is unknown, our findings suggest that PD-1 intrinsic expression in cDLBCL might contribute to tumor growth escaping adaptive immunity.

SHOX haploinsufficiency causes 70–90% of Léri-Weill dyschondrosteosis (LWD) and 2–10% of idiopathic short stature (ISS). Deletions removing the entire gene or enhancers and point mutations in the coding region represent a well-established cause of haploinsufficiency. During diagnostic genetic testing on ISS/LWD patients, in addition to classic SHOX defects, five 5′UTR variants (c.-58G > T, c.-55C > T, c.-51G > A, c.-19G > A, and c.-9del), were detected whose pathogenetic role was unclear and were thus classified as VUS (Variants of Uncertain Significance). The purpose of the present study was to investigate the role of these noncoding variations in SHOX haploinsufficiency. The variants were tested for their ability to interfere with correct gene expression of a regulated reporter gene (luciferase assay). The negative effect on the mRNA splicing predicted in silico for c.-19G > A was assayed in vitro through a minigene splicing assay. The luciferase assay showed that c.-51G > A, c.-19G > A, and c.-9del significantly reduce luciferase activity by 60, 35, and 40% at the homozygous state. Quantification of the luciferase mRNA showed that c.-51G > A and c.-9del might interfere with the correct SHOX expression mainly at the post-transcriptional level. The exon trapping assay demonstrated that c.-19G > A determines the creation of a new branch site causing an aberrant mRNA splicing. In conclusion, this study allowed us to reclassify two of the 5′UTR variants identified during SHOX diagnostic screening as likely pathogenic, one remains as a VUS, and two as likely benign variants. This analysis for the first time expands the spectrum of the genetic causes of SHOX haploinsufficiency to noncoding variations in the 5′UTR.

CONTEXT:The Gli-family of zinc-finger transcription factors regulates the Sonic Hedgehog (Shh) signalling pathway that plays a key role in early pituitary and ventral forebrain development. Heterozygous GLI2 loss of function mutations in humans have been reported in holoprosencephaly (HPE), HPE-like phenotypes associated with pituitary anomalies and combined pituitary hormone deficiency with or without other extra-pituitary findings.OBJECTIVE:The aim of this study was the search for GLI2 mutations in a cohort of Italian CPHD patients and the assessment of a pathogenic role for the identified variants through in vitro studies.PATIENTS:One hundred forty-five unrelated CPHD patients diagnosed with or without extra-pituitary manifestations were recruited from different Italian centres.METHODS:The GLI2 mutation screening was carried out through direct sequencing of all the 13 exons and intron-exon boundaries. Luciferase reporter assays were performed to evaluate the role of the detected missense variants.RESULTS:Five different novel heterozygous non-synonymous GLI2 variants were identified in five patients. The mutations were three missense (p.Pro386Leu, p.Tyr575His, p.Ala593Val), one frameshift (p.Val1111Glyfs*19) and one nonsense (p.Arg1226X). The latter two mutants are likely pathogenic since they lead to a truncated protein. The in vitro functional study of the plasmids bearing two of the three missense variants (namely p.Tyr575His and p.Ala593Val) revealed a significant reduction in transcriptional activity.CONCLUSION:In conclusion, the analysis of GLI2 in individuals with CPHD led to the identification of five variations with a likely negative impact on the GLI2 protein, confirming that GLI2 is an important causative gene in CPHD. The functional in vitro study analysis performed on the missense variations were useful to strengthen the hypothesis of pathogenicity.

Mutations of SHOX represent the most frequent monogenic cause of short stature and related syndromes. The genetic alterations include point mutations and deletions/duplications spanning both SHOX and its regulatory regions, although microrearrangements are confined to either the downstream or upstream enhancers in many patients. Mutations in the heterozygous state have been identified in up to 60–80% of Leri-Weill Dyschondrosteosis (LWD; MIM #127300) and approximately 4–5% of Idiopathic Short Stature (ISS; MIM#300582) patients. Homozygous or compound heterozygous mutations as well as biallelic deletions of SHOX and/or the enhancer regions result in a more severe phenotype, which is known as Langer Mesomelic Dysplasia (LMD; MIM #249700). A 17 year old girl, presented with severe short stature, growth hormone deficiency (GHD), precocious puberty, dorsal scoliosis, dysmorphisms and urogenital malformations. She was born with agenesis of the right tibia and fibula, as well as with a supernumerary digit on the left foot. Array comparative genomic hybridization (aCGH) analysis detected the presence of two distinct duplications on Xp22.1 flanking the SHOX coding sequence and involving its regulatory regions. An additional duplication of 1.6–2.5 Mb on 15q25.2 that included 13 genes was also identified. The girl was adopted and the parent’s DNA was not available to establish the origin of the chromosome imbalances. The complex phenotype observed in our patient is probably the result of the co-occurrence of rearrangements on chromosomes Xp22.1 and 15q25.2. The duplicated region on 15q25.2 region is likely to contain dosage-sensitive genes responsible for some of the clinical features observed in this patient, whereas the extreme short stature and the skeletal anomalies are likely attributable to the comorbidity of GHD and copy number variants in the SHOX region.

Background: Several association studies confirmed high-mobility group-A2 gene ( HMGA2 ) polymorphisms as the most relevant variants contributing to height variability. Animal models and deletions in humans suggest that alterations of HMGA2 might be relevant in causing short stature. Together, these observations led us to investigate the involvement of HMGA2 in idiopathic short stature (ISS) through an association study and a mutation screening. Methods: We conducted an association study (155 ISS patients and 318 normal stature controls) with three HMGA2 single-nucleotide polymorphisms (SNPs) (SNPs rs1042725, rs7968682, and rs7968902) using a TaqMan-based assay. The patients were then analyzed by direct sequencing and multiplex ligation-dependent probe amplification (MLPA) to detect point mutations and genomic micro-rearrangements. Results: Considering a recessive model, an OR value >1 was observed for genotypes rs7968682 TT (Odds ratio (OR) = 1.72, confidence interval (CI): 1.14–2.58) and rs1042725 TT (OR = 1.51, CI: 1.00–2.28) in accordance to the effect exhibited by the single alleles in the general population. None of the patients carried possibly causative HMGA2 mutations. Conclusion: Besides the already known role in determining variability in human height, HMGA2 polymorphisms also contribute to susceptibility to ISS. Moreover, we here report the first mutation screening performed in ISS concluding that HMGA2 has not a significant impact on the monogenic form of ISS.