Mutation in the SLC29A3 Gene in an Egyptian Patient with H Syndrome: A Case Report and Review of Literature

Combination of four features of SLC29A3 spectrum disorder in a child: A case report

SLC29A3 spectrum disorder, also known as histiocytosis-lymphadenopathy plus syndrome (HLPS), presents a wide variety of multi-systemic manifestations that can be mistaken for other conditions. Herein, we report a 9-year-old girl who presented with a complex clinical presentation since birth, including chronic generalized lymphadenopathy in association with hepatosplenomegaly, short stature, flexion contractures, hearing loss, hyperpigmentation, and heart anomalies. She was ultimately diagnosed with the SLC29A3 spectrum disorder.

Current phenotypic and genetic spectrum of syndromic deafness in Tunisia: paving the way for precision auditory health

Hearing impairment (HI) is a prevalent neurosensory condition globally, impacting 5% of the population, with over 50% of congenital cases attributed to genetic etiologies. In Tunisia, HI underdiagnosis prevails, primarily due to limited access to comprehensive clinical tools, particularly for syndromic deafness (SD), characterized by clinical and genetic heterogeneity. This study aimed to uncover the SD spectrum through a 14-year investigation of a Tunisian cohort encompassing over 700 patients from four referral centers (2007-2021). Employing Sanger sequencing, Targeted Panel Gene Sequencing, and Whole Exome Sequencing, genetic analysis in 30 SD patients identified diagnoses such as Usher syndrome, Waardenburg syndrome, cranio-facial-hand-deafness syndrome, and H syndrome. This latter is a rare genodermatosis characterized by HI, hyperpigmentation, hypertrichosis, and systemic manifestations. A meta-analysis integrating our findings with existing data revealed that nearly 50% of Tunisian SD cases corresponded to rare inherited metabolic disorders. Distinguishing between non-syndromic and syndromic HI poses a challenge, where the age of onset and progression of features significantly impact accurate diagnoses. Despite advancements in local genetic characterization capabilities, certain ultra-rare forms of SD remain underdiagnosed. This research contributes critical insights to inform molecular diagnosis approaches for SD in Tunisia and the broader North-African region, thereby facilitating informed decision-making in clinical practice.

Monogenic autoinflammatory disease-associated cardiac damage

INTRODUCTION

Autoinflammatory diseases (AIDs) constitute several disorders that are characterized by the presence of recurrent episodes of unprovoked inflammation due to dysregulated innate immune system in the absence of autoantibodies or infections. Most of them have a strong genetic background, with mutations in single genes involved in inflammation referred to monogenic AIDs. In this article, we will review the cardiac manifestations in various monogenic AIDs.

AREAS COVERED

Various cardiac manifestations can be seen in various monogenic AIDs, including pericarditis, valvular diseases, coronary diseases, cardiomyopathies, and pulmonary hypertension, especially in Familial Mediterranean fever (FMF).

EXPERT COMMENTARY

Monogenic AIDs can manifest a variety of cardiac lesions, the most common of which is pericardial effusion, which may be local pericardial inflammation secondary to systemic inflammatory responses. While, the pathogenesis and incidence are still unclear. More research is still needed to explore the relationship between monogenic AIDs and cardiac damage for better understanding these diseases.

Equilibrative nucleoside transporter 3 promotes the progression of hepatocellular carcinoma by regulating the AKT/mTOR signaling pathway

Equilibrative nucleoside transporter 3 (ENT3) belongs to the solute carrier family 29. Nucleoside transporters encoded by ENT3 play an important role in the uptake of nucleosides, nucleobases, and their nucleoside analogs, as well as participate in and regulate several physiological activities. However, no study has so far reported the role of ENT3 in hepatocellular carcinoma (HCC). We employed bioinformatics to analyze the expression, prognosis, and mechanism of ENT3 in HCC, as well as verified the same through biological experiments including cell proliferation, cell migration and invasion, and cell cycle and apoptosis, along with the detection of the AKT/mTOR protein expression in the pathway by Western blotting. ENT3 was widely and highly expressed in pan-cancer and upregulated in HCC. The upregulated ENT3 was related to the poor prognosis and clinical features in HCC patients. ENT3 knockdown inhibited cell proliferation, migration, and invasion and promoted cell apoptosis. ENT3 knockdown reduced the p-AKT and p-mTOR protein phosphorylation level, inhibited p-p70S6K1 and increased the p-4EBP1-the downstream effector of the AKT/mTOR pathway-protein phosphorylation level. Our study findings demonstrated that the expression of ENT3 was upregulated in HCC, which represents a poor prognosis. Thus, ENT3 promotes the progression of HCC through the AKT/mTOR signaling pathway.

Audiological findings of a patient with H syndrome: case report

Background

H syndrome is an autosomal recessive disorder caused by mutations in SLC29A3. Hyperpigmentation, hypertrichosis, hyperglycemia, and hearing loss are some characteristics of this disorder, and it has a prevalence of < 1/1000. The aim of this report is to spread awareness among otologists, audiologists, and pediatricians about this syndrome and its audiological features.

Case presentation

An 8-year-old male with a diagnosed H syndrome registered to our clinic with a complaint of hearing loss. The patient was diagnosed with hearing loss in a different clinic using only the air-conducted click auditory brainstem response test which showed wave V at 60 dB nHL for the right ear and at 80 dB nHL for the left ear. The initially performed pure tone audiometry (PTA) test in our clinic revealed a bilateral asymmetric hearing loss with a moderate sensorineural hearing loss in the right ear and a profound mixed hearing loss in the left ear. The performed air conducted click auditory brainstem response (ABR) result showed wave V at 55 dB nHL for the right ear and at 70 dB nHL for the left ear. Then, the repeated PTA test revealed a mild-severe sensorineural sloping hearing loss in the right ear and a severe sensorineural hearing loss in the left ear.

Conclusion

Although hearing thresholds in H syndrome could be within normal limits in some patients, sensorineural hearing loss is an important characteristic feature for this syndrome. Sensorineural hearing loss could be progressive or of sudden onset and ranges from mild to profound. Thus, it must be taken into consideration to apply the audiological follow-up regularly and paying attention to the patient’s complaints; also, a regular follow-up for language development of children with H syndrome and for the hearing aids is advised.

Pseudo-Meigs' Syndrome in Tunisian H Syndrome Female Patient: First Case Reported

H syndrome is an extremely rare autosomal recessive affection caused by biallelic mutations in the SLC29A3 gene encoding the human equilibrative nucleoside transporter hENT3. The hallmark signs are cutaneous consisting of hyperpigmentation and hypertrichosis patches. Besides, associated systemic manifestations are highly various reflecting phenotypic pleiotropism. Herein, we report a first case of pseudo-Meigs’ syndrome occurring in a young Tunisian H syndrome diagnosed patient with a novel homozygous frameshift mutation in exon 2 of the SLC29A3 gene: p.S15Pfs*86 inducing a premature stop codon. The patient developed ascites associated with left ovarian mass and she underwent surgery. After tumor resection, ascites disappeared rapidly. Histological examination showed serous cystadenoma of the ovary orienting the diagnosis towards pseudo-Meigs’ syndrome.

Facilitative lysosomal transport of bile acids alleviates ER stress in mouse hematopoietic precursors

Mutations in human equilibrative nucleoside transporter 3 (ENT3) encoded by SLC29A3 results in anemia and erythroid hypoplasia, suggesting that ENT3 may regulate erythropoiesis. Here, we demonstrate that lysosomal ENT3 transport of taurine-conjugated bile acids (TBA) facilitates TBA chemical chaperone function and alleviates endoplasmic reticulum (ER) stress in expanding mouse hematopoietic stem and progenitor cells (HSPCs). Slc29a3^−/− HSPCs accumulate less TBA despite elevated levels of TBA in Slc29a3^−/− mouse plasma and have elevated basal ER stress, reactive oxygen species (ROS), and radiation-induced apoptosis. Reintroduction of ENT3 allows for increased accumulation of TBA into HSPCs, which results in TBA-mediated alleviation of ER stress and erythroid apoptosis. Transplanting TBA-preconditioned HSPCs expressing ENT3 into Slc29a3^−/− mice increase bone marrow repopulation capacity and erythroid pool size and prevent early mortalities. Together, these findings suggest a putative role for a facilitative lysosomal transporter in the bile acid regulation of ER stress in mouse HSPCs which may have implications in erythroid biology, the treatment of anemia observed in ENT3-mutated human genetic disorders, and nucleoside analog drug therapy.

Mutations in ENT3, encoded by SLC29A3, result in anaemia and erythroid hypoplasia, suggesting roles in erythropoiesis. Here the authors show that ENT3 acts as a lysosomal bile acid transporter, and mutation compromises taurine conjugated bile acid transport in erythroid progenitors leading to ER stress, and anaemia.