Mutations in nuclear genes regulating mitochondrial DNA (mtDNA) replication are associated with mtDNA depletion syndromes. Using whole-genome sequencing, we identified a heterozygous mutation (c.272G>A:p.Arg91Gln) in single-stranded DNA-binding protein 1 (SSBP1), a crucial protein involved in mtDNA replisome. The proband manifested symptoms including sensorineural deafness, congenital cataract, optic atrophy, macular dystrophy, and myopathy. This mutation impeded multimer formation and DNA-binding affinity, leading to reduced efficiency of mtDNA replication, altered mitochondria dynamics, and compromised mitochondrial function. To correct this mutation, we tested two adenine base editor (ABE) variants on patient-derived fibroblasts. One variant, NG-Cas9-based ABE8e (NG-ABE8e), showed higher editing efficacy (≤30%) and enhanced mitochondrial replication and function, despite off-target editing frequencies; however, risks from bystander editing were limited due to silent mutations and off-target sites in non-translated regions. The other variant, NG-Cas9-based ABE8eWQ (NG-ABE8eWQ), had a safer therapeutic profile with very few off-target effects, but this came at the cost of lower editing efficacy (≤10% editing). Despite this, NG-ABE8eWQ-edited cells still restored replication and improved mtDNA copy number, which in turn recovery of compromised mitochondrial function. Taken together, base editing-based gene therapies may be a promising treatment for mitochondrial diseases, including those associated with SSBP1 mutations.

Background and Objectives: Wolfram syndrome type 1 (OMIM# 222300; ORPHAcode 3463) is an extremely rare autosomal recessive syndrome with a 25% recurrence risk in children. It is characterized by the presence of juvenile-onset diabetes mellitus (DM), progressive optic atrophy (OA), diabetes insipidus (DI), and sensorineural deafness (D), often referred to by the acronym DIDMOAD. It is a severe neurodegenerative disease with a life expectancy of 39 years, with death occurring due to cerebral atrophy. For a positive diagnosis, the presence of diabetes mellitus and optic nerve atrophy is sufficient. The disease occurs because of pathogenic variants in the WFS1 gene. The aim of this article is to present a case report of Wolfram Syndrome Type I, alongside a review of genetic variants, clinical manifestations, diagnosis, therapy, and long-term management. Emphasizing the importance of early diagnosis and a multidisciplinary approach, the study aims to enhance understanding and improve outcomes for patients with this complex syndrome. Materials and Methods: A case of a 28-year-old patient diagnosed with DM at the age of 6 and with progressive optic atrophy at 26 years old is presented. Molecular diagnosis revealed the presence of a heterozygous nonsense variant WFS1 c.1943G>A (p.Trp648*), and a heterozygous missense variant WFS1 c.1675G>C (p.Ala559Pro). Results: The molecular diagnosis of the patient confirmed the presence of a heterozygous nonsense variant and a heterozygous missense variant in the WFS1 gene, correlating with the clinical presentation of Wolfram syndrome type 1. Both allelic variants found in our patient have been previously described in other patients, whilst this combination has not been described before. Conclusions: This case report and review underscores the critical role of early recognition and diagnosis in Wolfram syndrome, facilitated by genetic testing. By identifying pathogenic variants in the WFS1 gene, genetic testing not only confirms diagnosis but also guides clinical management and informs genetic counseling for affected families. Timely intervention based on genetic insights can potentially reduce the progressive multisystem manifestations of the syndrome, thereby improving the quality of life and outcomes for patients.

Wolff-Parkinson-White (WPW) syndrome is a condition associated with tachycardia due to accessory pathways in the heart, and it is one of the most common causes of tachycardia in infants and children. WPW may also be associated with mitochondrial encephalomyopathy, lactic acidosis, stroke-like episodes (MELAS syndrome) or LEOPARD syndrome (LS). We report a case of pre-excitation WPW syndrome in a 17-year-old man who was brought to the hospital by ambulance following the collapse. WPW syndrome type A was diagnosed from precordial leads. Electrocardiography (ECG) revealed a short PR interval, delta waves, and positive waves with dominant R in all pericardial leads. Blood test results showed an isolated elevated ALT level. Subsequent echocardiography was unremarkable, with an ejection fraction of 55%, apart from septal and inferior wall dyssynchrony. With regard to the past medical history, he had sensorineural deafness (SND) since childhood and had a family history of SND. Consequently, the patient was transferred to the cardiac electrophysiology department at another hospital after consultation and underwent ablation. A successful post-ablation electrocardiogram revealed the resolution of the WPW syndrome signs and post-ablation features, such as peak T waves.

Sarcoidosis is a chronic multisystem granulomatous disease of unknown etiology. It is rare in young children. A 9-year-old boy presented with failure to thrive, skin rashes, persistent fever, and respiratory symptoms since 5 years of age. Blood investigations done showed elevated serum calcium and angiotensin converting enzyme levels and biopsy of the rashes on the left shin revealed non-caseating granulomatous lesion. Computed tomography of chest revealed interstitial lung disease and examination of eyes showed bilateral uveitis. He also had sensorineural hearing impairment, nephrocalcinosis, and short stature. The patient was treated with oral steroids and mycophenolate mofetil. At follow up, there was improvement in his systemic features including rashes and arthritis. Early detection, diagnosis, and appropriate treatment of sarcoidosis are vital for disease control and to avoid morbidity.

A heterozygous gain-of-function variant in the acyl-CoA oxidase 1 (ACOX1) gene, c.710A>G (p.Asn237Ser), is known to cause Mitchell syndrome, a very rare progressive disorder characterized by episodic demyelination, sensory polyneuropathy, and hearing loss. Only eight patients have been described so far. A single patient has been treated with intravenous immunoglobulin administration, indicating clinical improvement. In this study, we describe a 10-year-old girl carrying the identical mutation, who presented with progressive sensorineural deafness, visual abnormalities, skin ichthyosis, and gait ataxia from infantile age with progressive worsening and loss of walking ability by the age of 10 years. Antioxidant therapies and monthly intravenous immunoglobulin infusions showed excellent clinical results: after 1 year of treatment, the child is now able to walk, run, and jump. We emphasize the importance of early genetic diagnosis since an effective treatment is available for this rare condition.

Johanson-Blizzard syndrome (JBS) is a rare hereditary autosomal recessive disorder caused by a mutation in the ubiquitin protein ligase E3 component n-recognin 1 (UBR1) gene. This syndrome is characterized by the following typical clinical features: hypoplasia or aplasia of the alae nasi, congenital scalp defects, sensorineural hearing loss, hypothyroidism, growth retardation, psychomotor retardation, imperforate anus, genitourinary anomalies, and atypical hair patterns. Here, we describe a case of a 12-year-old girl with JBS of consanguineous parents. During the last trimester of pregnancy, a congenital abnormality affecting the nose was detected. Immediately after birth, the clinical examination revealed dysmorphic features in the form of hypoplastic alae nasi, microcephaly, mild hypotelorism, and cutis aplasia on the scalp. The genetic testing of the patient showed a novel sequence change mutation of the UBR1 gene (1bp duplication causing a frameshift), while both parents were carriers for this mutation. Moreover, a diagnosis of pancreatic insufficiency and subclinical hypothyroidism was made based on clinical presentation and laboratory results. The patient was started on pancreatic enzyme replacement therapy and fat-soluble vitamins, minerals, and antioxidant syrup. Further assessment revealed hypotonia, growth impairment, delay in reaching developmental milestones, and bilateral profound sensorineural hearing loss, which was managed with bilateral cochlear implantation. In addition, the patient underwent multiple craniofacial reconstructive surgeries. This case report highlights the importance of early diagnosis and multidisciplinary care of patients with JBS.

Chudley-McCullough syndrome (CMS) is a rare autosomal recessive disorder characterized by sensorineural hearing loss and cerebral abnormalities, including ventriculomegaly and partial dysgenesis of the corpus callosum. CMS is caused by two inactivating mutations of the G protein signaling modulator 2 (GPSM2), which maintains inner hair cell polarity and spindle orientation. Since its initial description, CMS has been reported approximately 30 times in the medical literature with several individuals undergoing cochlear implantation to restore their hearing. Interestingly, within the past two years, we encountered two cases of CMS in our hospital, which primarily serves patients within a 30-mile radius. To our knowledge, the literature has yet to evaluate two unrelated cases of CMS occurring in such close succession. This case report describes two successful cases of bilateral cochlear implantation in two children with CMS. Notably, these individuals have no family history of consanguinity or prior hearing loss.

BACKGROUND: Individuals with thiamine-responsive megaloblastic anemia (TRMA) mainly manifest macrocytic anemia, sensorineural deafness, ocular complications, and nonautoimmune diabetes. Macrocytic anemia and diabetes may be responsive to high-dosage thiamine treatment, in contrast to sensorineural deafness. Little is known about the efficacy of thiamine treatment on ocular manifestations.
METHODS: Our objective is to report data from four Italian TRMA patients: in Cases 1, 2 and 3, the diagnosis of TRMA was made at 9, 14 and 27 months. In 3 out of 4 subjects, thiamine therapy allowed both normalization of hyperglycemia, with consequent insulin suspension, and macrocytic anemia. In all Cases, thiamine therapy did not resolve the clinical manifestation of deafness. In Cases 2 and 3, follow-up showed no blindness, unlike Case 4, in which treatment was started for megaloblastic anemia at age 7 but was increased to high doses only at age 25, when the genetic diagnosis of TRMA was performed.
CONCLUSIONS: Early institution of high-dose thiamine supplementation seems to prevent the development of retinal changes and optic atrophy in TRMA patients. The spectrum of clinical manifestations is broad, and it is important to describe known Cases to gain a better understanding of this rare disease.

We present a rare manifestation of a common pathology: left sided sensorineural hearing loss secondary to subclavian steal syndrome after thoracic endovascular aortic repair for complicated acute aortic dissection. We describe the vascular physiology that can result in unilateral hearing loss and provide a brief review of subclavian steal syndrome. This case report highlights the importance of avid clinical recognition of an atypical presentation of a common vascular disease.

We report two cases of Alport syndrome and compare the clinical presentations and imaging findings in these cases. The clinical examination consisted of best-corrected visual acuity (BCVA), direct ophthalmoscopy, and slit-lamp examination. Macular optical coherence tomography (OCT) and anterior segment OCT (AS-OCT) and were utilized to document the details of the anterior and posterior segment pathologies. In order to evaluate systemic presentations of Alport syndrome, nephrology, and otolaryngology were consulted for each patient. In this study, the first case was a 27-year-old female with progressive myopia, anterior lenticonus, and temporal retinal thinning found in the ocular examination that led to the diagnosis of Alport syndrome. She underwent clear lens extraction and intraocular lens implantation, restoring acceptable visual acuity. The second case was a 20-year-old male patient with low visual acuity, severe bilateral anterior lenticonus, bilateral cataract, and temporal retinal thinning. The patient later developed renal failure and is a candidate for kidney transplantation. In this case report, progressive renal failure, hearing loss, and ocular abnormalities were all observed. This is consistent with previously reported cases given the typical characteristics of Alport syndrome, a rare inherited disease. The severity of those characteristics was higher in the male subject, a finding also consistent with prior reports indicating that males are usually affected more frequently and more severely than females, given that Alport syndrome is generally inherited as an X-linked disorder. Additionally, anterior segment and macular OCTs seemed to be of considerable significance in the early diagnosis of Alport syndrome given the typical ocular manifestations e.g. anterior lenticonus or temporal retinal atrophy.