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Introduction

According to previously published data, as well as reports from the World Health Organization, hearing loss of variable etiology represents a serious health, social and economic issue worldwide (1-3). With a prevalence varying between 1-3/1.000(4) and 1/500 newborns (5), congenital hearing loss is relatively frequent, and presents numerous difficulties in early diagnosis and treatment that could affect the optimal social integration of the infant. Genetic etiology has been identified in >50% of all cases of early onset hearing losses, of which, 75-80% are most probably autosomal recessive and 70% are non-syndromic (1-3). Other documented etiologies include clinical and environmental factors, such as ototoxic medication, prematurity or complications at birth (6). Due to the etiological heterogeneity of congenital hearing loss, genetic, clinical and environmental risk factors often combine to provide a complex picture that makes genetic evaluation and counselling difficult, especially for very young children (6).

Heterogenous gene mutations, which often require a complex diagnosis, can be responsible for complex and serious neurological conditions (7). Notably, 30% of congenital hearing loss cases are syndromic (1-3), and Radio-Tartaglia syndrome (RATARS) is a rare type, of which 34-45 global cases have been reported thus far (8). RATARS is a neurodevelopmental disorder caused by a heterozygous mutation in the SPEN gene localized in chromosome 1p36.21-36.13. The genetic mechanism involved is represented by autosomal dominant inheritance (8,9). The most frequent deletions of this chromosome are terminal and present a phenotype defined by a variety of clinical manifestations (8), including impaired intellectual development, speech delay, variable behavioral abnormalities [aggression, attention-deficit/hyperactivity disorder (ADHD), autism and impulsivity], ear malformations (hearing impairment), malformations of the head and neck, and malformations of the eyes, integumentary, cardiovascular, digestive, musculoskeletal and endocrine systems. An increase in the number of copies and mutations in this chromosome have also been documented in a small number of cases (10). As well as neurodevelopmental delay, RATARS is characterized by intellectual disability, language developmental delay and craniofacial dysmorphism (11). Information available about the distinctive features of this disease is scarce, delaying prompt management and the screening of associated conditions, which, in turn, may lead to reduced life expectancy.

The SPEN gene is part of the tumor-suppressor gene family, and has been reported to exert functions as a nuclear matrix platform, since it organizes and integrates any transcriptional responses within cells (8). It is hormonally induced through interactions with other repressor genes, especially those involved in the remodeling of chromatin, histone deacetylases and the entrapment of transcriptional activators (8,12). The importance of this gene in the human genotype has been verified by the observation that it serves an important role in several processes in neuronal development (12). Previous research on rodent models has shown that SPEN gene defects produce a reduction in brain mass, and a decrease in the thickness of the cerebral cortex and the hippocampus with subsequent ventriculomegaly (8,11,12).

The present case describes the association between severe congenital sensorineural hearing loss and a complex phenotype associated with a variant of the SPEN gene in a 5-year-old male child. The case is unique and important due to the rarity of this SPEN gene pathology, and to the intricate mechanisms underlying the effects of genetic and environmental risk factors on congenital severe sensorineural hypoacusis. To the best our knowledge, there have been no other reports regarding the association between SPEN gene and hypoacusis. The medical literature regarding RATARS is limited due to the global rarity of this disease.

Case report

The present study describes the case of a 5-year-old male patient born prematurely at 26 weeks and 6 days (June 2019; Filantropia Clinical Hospital, Bucharest, Romania), via caesarean section, after an uncomplicated pregnancy. The child was born with a very low birth weight (VLBW) of 1,300 g, length of 39 cm, cephalic perimeter of 28 cm, an Apgar score of 6 in the 1st min and 7 at 5 min after birth, and with difficult postnatal adaptation. The child required resuscitation and respiratory support (FiO2 30%; positive end-expiratory pressure, 6 cm H2O) immediately after birth. They were immediately admitted to the neonatal intensive care unit (NICU) where they were diagnosed with neonatal respiratory distress syndrome with a deficiency of surfactant, premature jaundice, apnea and osteopenia. The child was kept in a neutral thermal environment in an incubator, with orotracheal intubation, administered one dose of intratracheal surfactant (2.5 ml/kg) and mechanically ventilated for 5 days. Hemodynamic positive inotrope support (dopamine) was also necessary for the first 48 h. The tracheal tube was removed after 5 days, and non-invasive respiratory support was administered for another 5 days via nasal continuous positive airway pressure and for 18 days via high-flow nasal cannula. Supplementary free-flow oxygen at FiO2 #x003C;30% was necessary for the following 4 weeks coupled to the administration of caffeine intravenously and orally for apnea of prematurity. The patient slowly evolved towards balanced, normal physiological parameters.

At 6 weeks the child was transferred to the premature unit (July 2019; Filantropia Clinical Hospital, Bucharest, Romania) where they continued to develop slowly until they were discharged with a good general status; at discharge, they were in a cardiorespiratory and hemodynamically balanced state in atmospheric air pressure, had normal stethacoustic signs and were breast-fed. Health problems, a notable family history or consanguinity were not issues for either parent. During the first 4 years of life, the child was extensively investigated and closely monitored for the evolution of neuromotor development in various clinics until, in November 2023, the child was referred to the ‘Marie Sklodowska Curie’ Emergency Children's Hospital (Bucharest, Romania) where they were investigated by a multidisciplinary team, including ophthalmology (1st degree retinopathy with spontaneous remission); otorhinolaryngology with complete audiological testing [auditory brainstem response (ABR), behavioral observation audiometry that suggested severe bilateral hearing loss, middle-ear immittance audiometry, distortion product otoacoustic emissions absent from 1,500-4,000 Hz bilaterally); neurology; neurosurgery (normal exam); electroencephalogram; brain MRI; and whole exome sequencing (October 2023; myLifeGenome, Arcensus GmbH).

The milestones of the patient included hand grip at 4 months, sitting at 8 months, crawling at 12 months and independent walking at 23 months, although with precarious balance and coordination. By the age of 3 years, the patient was able to use a fork, pick up object with two fingers, chew and eat on their own, socialize but not interact in play groups and use ~10 meaningful words. Communication was primarily through gestures and facial expressions, and complex words were used only in specific contexts. Autism spectrum disorder was also diagnosticated.

The child did not have specific facies, and there were no craniofacial abnormalities or any other system affliction (e.g. cardiovascular, digestive, endocrine) reported thus far. The MRI showed nonspecific demyelinating lesions of the white matter (Fig. 1), a thin corpus callosum with irregular contour (Fig. 2) and a cyst of the septum pellucidum with no apparent clinical significance (Fig. 3). The eye exam noted 1st degree retinopathy with spontaneous remission.

Figure 1 Nonspecific demyelinating lesions of the white matter (fluid-attenuated inversion recovery signal hyperintensity; green arrow).

Figure 2 Thin corpus callosum with irregular contour (green arrow).

Figure 3 Cyst of the septum pellucidum with no apparent clinical significance (green arrow).

By the age of 4 years, the patient was referred to genetic counseling due to abnormal corpus callosum morphology, global developmental delay, hearing impairment, premature birth and short attention span (older brother affected with global developmental delay). Subsequently, whole exome sequencing was performed by myLifeGenome, Arcensus GmbH. The result revealed the presence of a variant of uncertain significance in heterozygous state in the SPEN gene, (c.8184_8185insGCGAGTGCAGTGAATGCCACA, p.Ala2729_Ser2730insSerAlaValAsnAlaThrAla); this variant was confirmed by Sanger analysis (Fig. 4). The child was also a carrier for other heterozygous variants without phenotypic effects in STAG3, MEI1 and DNALI1 genes. The genetic testing of both parents and older brother (November 2023; myLifeGenome; Arcensus GmbH) confirmed that the identified SPEN genetic variant in the index patient was inherited from the father (asymptomatic) and did not segregate within the family.

Figure 4 Results of Sanger analysis for the patient and his family members.

At the age of 4 years, extensive audiological and vestibular evaluations were performed as preliminary steps for a cochlear implant. The vestibular examination revealed a satisfactory labyrinthine function with a slight hypovalent labyrinth on the right side. The audiological examination included hearing assessment in the free field for specific frequencies and speech using behavioral observation audiometry, auditory steady state response audiometry (Fig. 5), ABR evaluation (Figs. 6 and 7), assessment of middle ear function using immittance audiometry and of cochlear outer hair cell function using otoacoustic emissions. Behavioral test results were obtained with fair reliability for the speech stimuli. Responses to speech stimuli were obtained at 70 dB HL in the sound field condition. No reliable responses to frequency-specific stimuli in the free field could be obtained; however, no noticeable behavioral responses to stimuli at the limits of the equipment were observed. Tympanometry revealed type A tympanograms bilaterally. Ipsilateral acoustic reflexes were absent at 1,000 Hz bilaterally. Distortion product otoacoustic emissions were absent from 1,500-4,000 Hz bilaterally. ABR showed no evoked response until 90 dBnHL bilaterally, with the presence of cochlear microphonics, indicating an auditory neuropathy. The auditory steady state response results indicated severe and bilateral hearing loss. The results of the hearing tests concluded severe hearing loss to sound stimuli in a sound field. No reliable responses to frequency-specific stimuli could be obtained. Middle ear pressure and mobility were normal. Acoustic reflexes were absent bilaterally. Otoacoustic emissions suggested abnormal cochlear outer hair cell function bilaterally.

Figure 5 Auditory steady state response results indicated severe bilateral sensorineural hearing loss.

Figure 6 Auditory evoked potentials results. Cochlear microphonic potentials were observed bilaterally.

Figure 7 Auditory evoked potentials results (extended results). No evoked response until 90 dB nHL bilaterally.

The young patient's hypoacusis was initially treated with hearing aids and speech therapy with poor results. Subsequently they underwent cochlear implantation in September 2024 at the ‘Marie Sklodowska Curie’ Emergency Children's Hospital. The implant was activated in December 2024 and showed excellent results within the first month of use. At present, the child refuses to wear the classic hearing aid on the contralateral ear and has suggested that they desire a similar implant for the other ear.

Discussion

Congenital sensorineural hypoacusis has different etiologies, both genetic and non-genetic. Notably, prematurity is known to produce hypoacusis, often in association with developmental delay, as in the present patient. A particularity of the present case was the association of a novel variant of the SPEN gene. This variant was inherited from the healthy father and classified as a variant with unknown significance. Pathogenic variants of the SPEN gene have been reported to be associated with RATARS, a rare genetic syndrome with only ~45 previously reported cases (8), which is characterized by global developmental delay, hypotonia, brain malformations (including polymicrogiria, heterotopia, thin corpus callosum, cerebellar atrophy, periventricular white matter anomalies), behavioral problems (autism, hyperkinesia, aggression), heart malformations and dysmorphic facial features. The current patient also presented with some of these features (global developmental delay, autistic behavior, abnormal corpus callosum) (11). The role of this SPEN gene variant in the phenotype, together with the effect of prematurity on development, was taken into consideration in the present case. The SPEN gene encodes a protein that is involved in neurogenesis and acts as a transcriptional repressor. It has an important role in a number of cellular processes, including cell division, adhesion and migration, and neuronal development, with implications in learning and memory processes (11). To the best of our knowledge, the variant described in the present case has not been reported before, both in the general population and in patient databases; therefore, it is difficult to predict the effect of this variant on the patient phenotype, and a definitive connection between the patient phenotype and the SPEN gene variant could not be made. Functional studies or reports of other cases with this variant could contribute to a better classification of this gene variant.

In the present case, the presence of prematurity and numerous other risk factors associated with the early postnatal state (VLBW, low Apgar score, NICU admission, respiratory distress syndrome and the need for respiratory support) cannot be ignored as a likely cause for congenital hypoacusis. Notably, we can only speculate on the association of the SPEN gene mutation with this patient due to its role in neural development.

The presence of congenital sensorineural hypoacusis, especially when associated with neurodevelopmental delay and intellectual disability at an early age, should be investigated by genetic sequencing, as heterogeneity between most genetic pathologies is present (12). Congenital hypoacusis of syndromic origin (30%) is far more rare than that of non-syndromic origin (70%) (13) and the presence of the SPEN mutation in the 1p36 chromosome, associated with RATARS, represents an extremely rare find. The presence of only ~45 reported cases of RATARS worldwide makes the diagnosis in this case challenging (8).

The SPEN gene serves an important role in neuronal development. In vivo rodent experiments have shown that gene defects produce a reduction in brain mass, as well thinning of the cortex and hippocampus (11,12,14-16). These results have been verified by clinical observations of patients with RATARS. In 64% of cases, important neurological abnormalities have been reported (8). Of all the abnormalities identified by imaging in patients with RATARS (white matter abnormalities, agenesis of the corpus callosum, cerebellar atrophy and polymicrogyria), the present case exhibited minimal white matter abnormalities and a thin, irregular corpus callosum. Such cerebral malformations are associated with obvious clinical neurological effects including: Motor and developmental delay, cerebral ataxia, seizures, intellectual disability, ADHD, psychiatric and behavioral abnormalities (impulsivity, aggressive behavior, reduced eye contact, motor stereotypes) and autism spectrum disorder, some of which have also been reported in the present patient (17).

In 2021, Radio et al (12), reported on 34 patients with RATARS. These patients were diagnosed through genetic and Sanger sequencing in which heterozygous mutations of the SPEN gene (613484.0001-613484.0005) were reported (8). These mutations have not yet been described in the gnomAD database, and the patients were verified through the GeneMatcher program (18) and DECIPHER database (19). In most cases there was no association between genotype and phenotype, and the mutations occurred de novo. The methylation profile of the genome did not show much difference between cells in the normal population compared with in the patients in a clinical trial conducted by Radio et al in 2021(12).

Williams syndrome (WS) is very similar to RATARS and is defined as an autosomal dominant multisystemic disorder caused by a microdeletion on chromosome 7q11.23, a region that contains 26-28 genes including the ELN gene (20,21). It is also associated with intellectual disability, facial abnormalities and arteriopathy, which makes a clinical differential diagnosis unreliable. Both pathologies present reduced cerebral volume, which leads to developmental and intellectual delay associated with psychiatric disorders (anxiety, phobias, ADHD, impulsivity, aggression, motor/behavioral stereotypes, such as thumb sucking, nail or lip biting, hair twirling, body rocking, self-biting, teeth clenching or grinding and head banging). However, RATARS may express more neurological features such as: Polymicrogyria, cerebellar atrophy, corpus callosum agenesis or tethered cord syndrome (12,20). There are some clinical features that are present both in RATARS and WS, such as bitemporal narrowing, prominent bulbous nasal tip, long nasal philtrum, muscle hypotonia, global developmental delay, and mild to moderate intellectual disability. Regarding facial dysmorphisms, a broad forehead, dysplastic ears, arched elongated eyebrows, epicanthus and synophrys are reported as common for patients with RATARS (12). Although both syndromes are associated with facies, these are not distinctive but rather suggestive of a genetic pathology. This is not the case for the present patient, as they did not present with any specific or distinctive facies. RATARS may present with frontal bossing, telecanthus, arched elongated eyebrows, a pointed chin and dental abnormalities, whereas WS typically presents with ‘elf-like’ features with epicanthic folds, puffiness around the eyes, small widely spaced teeth, a small jaw and full cheeks (20-22). Psychiatric conditions, including ADHD, autism, aggressive behavior and anxiety, are very common in RATARS compared with in WS (12). In addition, congenital heart defects have been reported in both syndromes, but in RATARS they are represented by ventricular and atrial septal defects, whereas in WS they are represented by supravalvular aortic stenosis or pulmonary stenosis. Regarding the genetic defect, WS is caused by a microdeletion on chromosome 7q11.23, whereas in patients with RATARS heterozygous mutations of the SPEN gene are the cause (8).

In conclusion, the present findings indicated that a patient with no craniofacial dysmorphism or specific facies, with neurodevelopmental delay but normal laboratory analyses and slightly modified brain images, associated with severe congenital sensorineural hypoacusis should be considered as a possible RATARS case and should undergo exome sequencing for a definitive diagnosis.

The novel variant of the SPEN gene described in the present case was inherited by the patient from their healthy father and was classified as a variant with unknown significance. Since the patient also had severe pre- and postnatal issues, such as VLBW, low Apgar score, NICU admission, respiratory distress syndrome and the need for respiratory support, which are documented causes of congenital hearing loss, it is difficult to predict the effect of this gene variant on the patient phenotype. Functional studies or reports of other cases with this variant could contribute to a better classification of this gene variant.

RATARS represents an extremely rare genetic syndrome and possible cause of congenital sensorineural hearing loss associated with neurodevelopmental delay, intellectual disability and multiple systemic manifestations that share several characteristics with other genetic pathologies. The number of reported cases varies from 34 to 45 worldwide. The lack of information about the distinctive features of RATARS leads to delayed diagnosis and management which, in turn, affects the screening of associated conditions and life expectancy. The clinical complexity of patients with RATARS, including the presence of hearing loss and precarious language development, indicates the need to further establish more clear parameters of the disease so that it does not go undiagnosed.

Taking into account the global scarcity of reported cases of RATARS with pathogenic variants of the SPEN gene, the publication of this case may increase the interest for further research studies into this gene. A more accurate diagnosis could be provided through future research directions, including functional cell or animal model experiments, to observe the impact of this variant on relevant cell processes and phenotypes, thereby clarifying the causal relationship between the variant and disease.

Acknowledgements

Not applicable.

Funding

Funding: No funding was received.

Availability of data and materials

The data generated in the present study are included in the figures and/or tables of this article.

Authors' contributions

ACN and HM conceptualized the study. ACN, HM and MB devised and approved the methodology. AIM, MED, DMP and RN were responsible for using software and graphical representations. ACN, MB and HM performed validation. AIM, MED, DMP, RN and DCG performed formal analysis. ACN, HM and MED were in charge of running the investigation. AIM, MED, RN and DMP were responsible for resources (provision of study materials, medical materials, patients, laboratory samples and results, computing resources, or other analysis tools). HM, MB, AIM and RN provided data curation (data management, maintaining research data for initial use and later reuse). MB and HM were responsible for writing the original draft. ACN and MED were responsible for review and editing. ACN, HM and MB provided visualization (transforming the raw medical data, such as medical reports, imaging results or patient information, into visual representations such as charts, graphs or images to facilitate understanding and interpretation). DCG and HM were in charge of supervision. HM, MB and MED were responsible for project administration. ACN and HM confirm the authenticity of all the raw data. All authors have read and approved the final version of the manuscript.

Ethics approval and consent to participate

The study was conducted in accordance with The Declaration of Helsinki, and was approved by the Ethics Committee of the ‘Titu Maiorescu’ University (approval no. 16/06.12.2024; Bucharest, Romania). All legal guardians (parents) provided informed written consent.

Patient consent for publication

The patient's legal guardians (parents) provided written informed consent for the publication of data from the proband, proband's brother and themselves.

Competing interests

The authors declare that they have no competing interests.

References