TBX4 gene, located on human chromosome 17q23.2, encodes for T-Box Transcription Factor 4, a transcription factor that belongs to the T-box gene family and it is involved in the regulation of some embryonic developmental processes, with a significant impact on respiratory and skeletal illnesses. Herein, we present the case of a female neonate with persistent pulmonary hypertension (PH) who underwent extracorporeal membrane oxygenation (ECMO) on the first day of life and then resulted to have a novel variant of the TBX4 gene identified by Next-Generation Sequencing. We review the available literature about the association between PH with neonatal onset or emerging during the first months of life and mutations of the TBX4 gene, and compare our case to previously reported cases. Of 24 cases described from 2010 to 2023 sixteen (66.7%) presented with PH soon after birth. Skeletal abnormalities have been described in 5 cases (20%). Eleven cases (46%) were due to de novo mutations. Three patients (12%) required ECMO. Identification of this variant in affected individuals has implications for perinatal and postnatal management and genetic counselling. We suggest including TBX4 in genetic studies of neonates with pulmonary hypertension, even in the absence of skeletal abnormalities.

Acinar dysplasia (AcDys) of the lung is a rare lethal developmental disorder in neonates characterized by severe respiratory failure and pulmonary arterial hypertension refractory to treatment. Recently, abnormalities of TBX4-FGF10-FGFR2-TMEM100 signaling regulating lung development have been reported in patients with AcDys due to heterozygous single-nucleotide variants or copy-number variant deletions involving TBX4, FGF10, or FGFR2. Here, we describe a female neonate who died at 4 hours of life due to severe respiratory distress related to AcDys diagnosed by postmortem histopathologic evaluation. Genomic analyses revealed a novel deleterious heterozygous missense variant c.728A>C (p.Asn243Thr) in TBX4 that arose de novo on paternal chromosome 17. We also identified 6 candidate hypomorphic rare variants in the TBX4 enhancer in trans to TBX4 coding variant. Gene expression analyses of proband\'s lung tissue showed a significant reduction of TMEM100 expression with near absence of TMEM100 within the endothelium of arteries and capillaries by immunohistochemistry. These results support the pathogenicity of the detected TBX4 variant and provide further evidence that disrupted signaling between TBX4 and TMEM100 may contribute to severe lung phenotypes in humans, including AcDys.

Chordoma is a rare malignant tumor with notochordal differentiation, usually affecting the axial skeleton of young patients. We report a case of a high-grade epithelioid tumor involving the synovium and soft tissues of the knee in a 74-year-old male patient. The preliminary biopsy was inconclusive, but a diagnosis of metastatic clear-cell carcinoma of unknown origin was suggested. However, imaging studies did not reveal any primary lesions. The resection specimen consisted of nests and sheets of oval to polygonal cells with discernible cell borders, clear or lightly amphophilic cytoplasm, and round to oval nuclei with occasional well-visible eosinophilic nucleoli. Rare atypical mitoses, necrotic areas, and bizarre nuclei were noted. The biopsy and resection specimens underwent a wide molecular genetic analysis which included methylation profiling. The DKFZ sarcoma classifier assigned the methylation class chordoma (dedifferentiated) with a calibrated score of 0.96, and additionally, a loss of SMARCB1 locus was noted in the copy number variation plot. To verify these findings, T-brachyury and SMARCB1 immunostaining was performed afterward, showing diffuse nuclear positivity and complete loss in the tumor cells, respectively. To assess the prevalence of T-brachyury immunopositivity among SWI/SNF-deficient tumors and to evaluate its specificity for poorly differentiated chordoma, we analyzed a series of 23 SMARCB1- or SMARCA4-deficient tumors, all of which were negative. After incorporating all the available data, including the absence of any morphological features of conventional chordoma, the case was diagnosed as poorly differentiated chordoma. As illustrated herein, the utilization of methylation profiling in the diagnostic process of some carefully selected unclassifiable soft tissue neoplasms may lead to an increased detection rate of such extremely rare soft tissue tumors and enable their better characterization.

Holt-Oram syndrome or atriodigital dysplasia is commonly associated with cardiac malformations, most often with defects of the muscular septum. We describe the case of a fetus referred for fetal cardiology evaluation in the setting of right atrial enlargement without tricuspid valve abnormalities with small muscular VSDs, and without other significant cardiac lesions. On serial fetal echocardiograms, isolated right atrial enlargement was persistent as was relative fetal bradycardia without apparent AV block or other signs of abnormal conduction. Limb or other anatomic abnormalities were also not visualized on prenatal scans. A postnatal diagnosis of Holt-Oram Syndrome was made. In the setting of isolated right atrial enlargement, we suggest a comprehensive sonographic search for upper limb abnormalities as well as genetic evaluation.

Copy number variations (CNVs) in TBX21 gene have been reported to be significantly and positively correlated with acute anterior uveitis (AAU). Our study was performed to further determine whether single nucleotide polymorphisms (SNPs) in TBX21 gene confer susceptibility to AAU in a Chinese population. In our case-control study, 420 AAU patients and 918 healthy controls were included. SNP genotyping was conducted via the MassARRAY™ iPLEX Gold platform. Association and haplotype analyses were performed via SPSS 23.0 and SHEsis software. No significant association was observed between two candidate SNPs of TBX21 gene (rs4794067, rs11657479) and susceptibility to AAU (Pc > 0.05). In stratification analysis, the result also showed no significant difference between the HLA-B27 positive AAU patients and non-typed healthy controls. Additionally, no association was detected between TBX21 haplotypes and AAU risk. In conclusion, the polymorphisms rs4794067 and rs11657479 in TBX21 gene did not confer disease susceptibility to AAU in a Chinese population.

Ulnar-Mammary syndrome (UMS) is a rare monogenic disorder caused by mutations of the TBX3 gene. This paper reported a family of UMS. The proband, a 15-year old man, was presented with mammary gland dysplasia, ulnar limb defect, short stature, and delayed growth. Whole exome sequencing revealed a 1294_1301dup mutation in exon 6 of the TBX3 gene. Sanger sequencing was used to verify other members of the family, which suggested his mother also carried the same mutation, but merely resulting in the dysplasia of her left little finger. Notably, unilateral finger involvement without any systemic organ involvement was unusual in UMS patients. The proband then was treated with recombinant human growth hormone (rhGH) and human chorionic gonadotropin (hCG). After a year and a half, his height and secondary sexual characteristics were significantly improved. The clinical manifestations of the disease are highly heterogeneous, which is easy to be misdiagnosed and missed. When the diagnosis is unclear, genetic testing is helpful for auxiliary diagnosis.
Ulnar-Mammary综合征(Ulnar-Mammary syndrome，UMS)是由TBX3基因突变所致的一种罕见单基因遗传病。本文报告1个UMS家系，先证者为15岁男性患者，表现为乳腺发育不良、尺侧肢体缺陷、身材矮小和发育迟缓。全外显子测序发现其TBX3基因的第6外显子存在1294_1301dup变异。用Sanger测序验证家系中其他成员，结果提示患者母亲也携带同样的突变，但仅表现为左侧小指发育异常。仅单侧手指受累而无任何系统器官受累的UMS患者鲜有报道。予患者重组人生长激素(recombinant human growth hormone，rhGH)和人绒毛膜促性腺激素(human chorionic gonadotropin，hCG)治疗1年半，身高及第二性征均得到明显改善。该疾病的临床表现异质性强，容易误诊漏诊，当诊断不明时，基因检测有助于辅助诊断。.

Congenital athymia can present with severe T cell lymphopenia (TCL) in the newborn period, which can be detected by decreased T cell receptor excision circles (TRECs) on newborn screening (NBS). The most common thymic stromal defect causing selective TCL is 22q11.2 deletion syndrome (22q11.2DS). T-box transcription factor 1 (TBX1), present on chromosome 22, is responsible for thymic epithelial development. Single variants in TBX1 causing haploinsufficiency cause a clinical syndrome that mimics 22q11.2DS. Definitive therapy for congenital athymia is allogeneic thymic transplantation. However, universal availability of such therapy is limited. We present a patient with early diagnosis of congenital athymia due to TBX1 haploinsufficiency. While evaluating for thymic transplantation, she developed Omenn Syndrome (OS) and life-threatening adenoviremia. Despite treatment with anti-virals and cytotoxic T lymphocytes (CTLs), life threatening adenoviremia persisted. Given the imminent need for rapid establishment of T cell immunity and viral clearance, the patient underwent an unmanipulated matched sibling donor (MSD) hematopoietic cell transplant (HCT), ultimately achieving post-thymic donor-derived engraftment, viral clearance, and immune reconstitution. This case illustrates that because of the slower immune recovery that occurs following thymus transplantation and the restricted availability of thymus transplantation globally, clinicians may consider CTL therapy and HCT to treat congenital athymia patients with severe infections.

Left ventricular non-compaction cardiomyopathy (LVNC) is a rare heart disease, with or without left ventricular dysfunction, which is characterized by a two-layer structure of the myocardium and an increased number of trabeculae. The study of familial forms of LVNC is helpful for risk prediction and genetic counseling of relatives. Here, we present a family consisting of three members with LVNC. Using a next-generation sequencing approach a combination of two (likely) pathogenic nonsense mutations DSG2-p.S363X and TBX20-p.D278X was identified in all three patients. TBX20 encodes the cardiac T-box transcription factor 20. DSG2 encodes desmoglein-2, which is part of the cardiac desmosomes and belongs to the cadherin family. Since the identified nonsense variant (DSG2-p.S363X) is localized in the extracellular domain of DSG2, we performed in vitro cell transfection experiments. These experiments revealed the absence of truncated DSG2 at the plasma membrane, supporting the pathogenic relevance of DSG2-p.S363X. In conclusion, we suggest that in the future, these findings might be helpful for genetic screening and counseling of patients with LVNC.

Evolution of poorly differentiated chordoma from conventional chordoma has not been previously reported. We encountered a case of a poorly differentiated chordoma with evidence of whole-genome doubling arising from a SMARCB1-deficient conventional chordoma. The tumor presented as a destructive sacral mass in a 43-year-old man and was comprised of a highly cellular poorly differentiated chordoma with small, morphologically distinct nodules of conventional chordoma accounting for <5% of the total tumor volume. Immunohistochemistry (IHC) revealed both components were strongly reactive for brachyury and lacked normal staining for INI1. Single nucleotide polymorphism (SNP) array analysis identified multiple genomic imbalances in the conventional component, including deletions of 1p, 3p, and 22q (involving SMARCB1) and loss of chromosomes 5 and 15, while the poorly differentiated component exhibited the same aberrations at a more profound level with additional loss of chromosome 4, low level focal deletion of 17p (involving TP53), and tetraploidy. Homozygous deletion of SMARCB1 was present in both components. Fluorescence in situ hybridization (FISH) analysis confirmed the relevant deletions in both components as well as genome doubling in the poorly differentiated tumor. This case suggests that SMARCB1 loss is an early event in rare conventional chordomas that could potentially evolve into poorly differentiated chordoma through additional genomic aberrations such as genome doubling. Further studies with additional patients will be needed to determine if genome doubling is a consistent pathway for evolution of poorly differentiated chordoma.

A surgical case of a benign notochordal cell tumor of the lung is reported. The patient was an asymptomatic 41-year-old man, who was incidentally found to have a small tumor in the subpleural region of the left lingular segment. Since wedge resection of the tumor, the patient has been free from recurrence. The tumor measured 12 mm in diameter and showed a central cystic change. It consisted of a diffuse proliferation of polygonal cells with abundant, uni- or multi-vacuolated cytoplasm and bland nuclei. The tumor did not show a lobular architecture and lacked a myxoid or fibrous connective tissue containing blood vessels. In the peripheral region of the tumor, a small number of alveolar epithelial cells were entrapped. The nuclei of tumor cells were immunoreactive for brachyury, and the cytoplasm was positive for cytokeratin and S-100 protein. The entrapment of alveolar epithelial cells suggests infiltrative growth of the tumor, and the almost complete absence of blood vessels within the tumor may have restricted tumor growth and induced a cystic change in the central region.