A Comparative Study of Hearing Loss in Two Microdeletion Syndromes: Velocardiofacial (22q11.2 Deletion) and Williams (7q11.23 Deletion) Syndromes

Prevalence of hearing loss and clinical otologic manifestations in patients with 22q11.2 deletion syndrome: A literature review

“…Conductive hearing loss was most prevalent in most studies (range 5.6% to 53%). In only two studies sensorineural hearing loss or mixed hearing loss was present in more patients compared to conductive type hearing loss . The rate of sensorineural and mixed hearing loss in the included studies differed from 0% to 19.4% and from 0% to 28.2% respectively.…”

“…Also, the frequencies at which the PTA was calculated differed as some authors used 0.5, 1 and 2 kHz, others used the frequencies 0.5, 1, 2 and 4 kHz, and one study defined hearing loss at a hearing threshold below 15 dB at any frequency . In two articles, the method of calculation was not mentioned . Rates of hearing loss, all types of hearing loss included, varied from 6.0% to 60.3%.…”

“…Rates of hearing loss, all types of hearing loss included, varied from 6.0% to 60.3%. Aside from decreased hearing thresholds in standard frequencies, Van Eynde et al and Zarchi et al found hearing loss to be more present and more severe in the high tones (Van Eynde et al measured thresholds at 4, 8, 9, 10 and 11.2 kHz and Zarchi et al at (4), 6 and 8 kHz). Conductive hearing loss was most prevalent in most studies (range 5.6% to 53%).…”

“…The rate of sensorineural and mixed hearing loss in the included studies differed from 0% to 19.4% and from 0% to 28.2% respectively. The severity of hearing loss was reported by nine studies and was mostly of mild severity (≤40 dB) …”

Modeling a model: Mouse genetics, 22q11.2 Deletion Syndrome, and disorders of cortical circuit development

“…The anomalies recognized in fetuses, some of which may contribute to pre-natal demise, include regional dysmorphology of the developing forebrain including arhinen-cephaly—apparent absence of the olfactory bulbs and related forebrain regions (Noel et al, 2014). Those seen post-natally in patients, which can be clinically challenging for individual patients, include malformations of the hands and feet (Ming et al, 1997), short stature and skeletal malformations (Ming et al, 1997); sensory-neural hearing loss detected during early life (Dyce et al, 2002; Zarchi et al, 2011); oculo-motor disturbances (Sobin et al, 2006); and perinatal feeding and swallowing difficulties that are likely related to velopharyngeal insufficiency seen in 22q11DS (Eicher et al, 2000; Rommel et al, 2008). The variable frequency of these 22q11DS-associated anomalies suggests that they reflect developmental mechanisms that are even more sensitive to genetic, environmental, toxic, and modifying mechanisms.…”