Management of children with auditory neuropathy spectrum disorder (ANSD)

The Clinical Journey of Patients with Riboflavin Transporter Deficiency Type 2

PURPOSE

To identify symptoms and health care interactions with patients with riboflavin transporter deficiency (RTD) type 2 prior to diagnosis.

METHODS

Parents of children with riboflavin transporter deficiency type 2 (n = 10) were interviewed to collect data on the patient's clinical journey.

RESULTS

The average diagnostic delay was 27.6 months. Neurologists were the most commonly visited clinician (90%). Common symptoms during the first year of the patient's clinical journey included abnormal gait and/or ataxia (70%), nystagmus (50%), and upper body muscle weakness (40%). Prior to diagnosis, optic atrophy, sleep apnea, breath-holding spells, and dysphagia were commonly observed. Hearing loss was only reported in 40% of subjects prior to diagnosis. Riboflavin responsive megaloblastic anemia is reported for the first time. Mitochondrial disease was the most common suspected diagnosis (30%).

CONCLUSION

Despite clinical variability, common early symptoms of riboflavin transporter deficiency type 2 exist that can better allow clinicians to more rapidly identify riboflavin transporter deficiency type 2.

AIF knockdown induce apoptosis and mitochondrial dysfunction in cochlear spiral ganglion neurons in vitro

The underlying mechanism involved in auditory neuropathy spectrum disorder (ANSD) remains largely unclear. It has been previously reported that mutations in the apoptosis-inducing factor (AIF) gene are associated with auditory neuropathy and delayed peripheral neuropathy, which can eventually cause ANSD. In the present study, the regulatory effects of AIF knockdown on the cellular functions of spiral ganglion neurons (SNGs) and the molecular mechanism(s) of AIF knockdown in inducing cell apoptosis in SGNs were further investigated. The results showed that the AIF knockdown via siRNA transfection resulted in high levels of oxidative stress, and impaired mitochondrial respiration activity and membrane potential in SGNs. Western blotting further proved that the knockdown of AIF can decrease the content of anti-apoptotic and anti-oxidative proteins, as well as mitochondrial respiratory chain Complex I proteins. The present experimental data suggested that the abnormal expression of AIF may affect SGNs cellular function, and may contribute to the progress of ANSD.