1. Auditory findings in Smith-Lemli-Opitz syndrome (SLOS)
Tiffany Pointon, MD
Deborah Hayes, PhD
Ellen Roy Elias, MD

2. Introduction
Autosomal recessive disorder- mutations in DHCR7 gene
Results in cholesterol deficiency and accumulation of precursors 7- and 8-dehydrocholesterol (7-DHC and 8- DHC)1,2,3
Cholesterol is vital for production of bile acids and hormones, cell membranes and cell signaling.
7-DHC is oxidized 4,5,6 forming oxysterols that have been shown to reduce cell viability7,8

3. SLOS clinical characteristics
Cognitive/developmental disability
Cleft palate
2-3 toe syndactyly
Photosensitivity
Sensorineural hearing loss has been described in case reports9,10
hearing and auditory function have not been further characterized.

4. SLOS treatment Cholesterol supplementation
Improves biochemical parameters, photosensitivity, growth, infection tolerance
Oxysterols may play a role in SLOS
Antioxidants decrease oxysterol levels11,12
AquADEKs™ antioxidant preparation chosen as antioxidant of choice as it has proven safe in pediatric patients

5. The goal of this study was:
Analyze hearing status and auditory pathway function in SLOS
Determine if treatment with cholesterol and the antioxidant preparation AquADEKs™ has an effect on auditory outcomes over time

6. Methods
Participants
24 patients with biochemically and/or genetically confirmed SLOS were enrolled in the COMIRB approved protocol at Children’s Hospital Colorado between and 2016.
15 males, 9 females
Average age was 10 years (range 13 days to 49 years)

7. Methods Auditory Brainstem Response (ABR)13

8. Methods
Tympanometry: an objective test of middle ear function conducted by varying air pressure in the external ear canal and measuring acoustic energy transmission through the middle ear.
Otoacoustic emissions (OAEs): an objective test of cochlear sensory cell function obtained by measuring acoustic energy produced when outer hair cells, which act as a cochlear amplifier, vibrate in response to stimulation.
Auditory steady state response (ASSR): an auditory evoked potential elicited by modulated pure-tones which can be used to predict the pure-tone audiogram

9. Methods Treatment – started at enrollment
Cholesterol suspension (200 mg/ml and/or other cholesterol sources) with doses of mg/kg/day divided tid
AquADEKs™
Vitamins A, D, E, K
Vitamin C
B Vitamins
Selenium
Coenzyme Q10

10. Average sterol labs at diagnosis grouped by sterol ratio severity
Mild
N=7
Moderate
N=10
Severe
Serum
Cholesterol (mg/dL)
152.6
(93-193)
129
(88-191)
47.9
(12-83)
7-DHC (mg/dL)
1.1
( )
5.2
( )
21.3
( )
8-DHC (mg/dL)
0.9
( )
4.51
( )
14.3
( )
Sterol Ratio (%)
( )
7.8
( )
186.1
( )
Sterol ratio ranges:
Mild (0-3.5), Moderate (3.6-17), Severe (>17).
Sterol Ratio : (7-DHC+ 8-DHC)/ cholesterol x 100
7-DHC reference range: mg/dL.
Ranges listed in parentheses

11. Baseline hearing status in patients with SLOS
N=47 ears
57% (27/47 ears) with normal hearing
19% (9/47 ears) with sensorineural hearing loss
15% (7/47 ears) with conductive hearing loss
9% (4/47 ears) with mixed hearing loss

12. Characteristics of patients at baseline grouped by hearing status
Normal Hearing
Sensorineural HL
Conductive HL
Mixed HL
N=27
N=9
N=7
N=4
Average Age (years)
9.9
(0.6-28)
11.3
(0.3-23)
4.1
(0.8-21)
25.4
(1.8-49)
Baseline cholesterol level
(mg/dL)
130.5
(32-193)
94.3
(53-154)
98.1
(31-190)
73.5
(12-135)
Baseline Sterol Ratio (%)
13.8
( )
22.3
( )
23.6
( )
283.32
( )
Hearing loss at birth 2
Submucosal cleft palate 6 1
Hard palate cleft palate 3
Cholesterol supplementation >6months at baseline 7
*Ranges listed in parentheses

13. Longitudinal Hearing
Hearing status was relatively stable over time on Cholesterol and AquADEKs™ in 21/24 patients
Of the 3 patients with changes:
One moderately affected patient with unilateral sensorineural hearing loss at baseline had normal hearing at repeat testing on treatment
Two pediatric patients with normal/borderline hearing showed sensorineural hearing loss at follow-up

14. Baseline Auditory Brainstem Response (ABR)
36% (17/47 ears) had a prolonged wave I-V interval
53% (25/47 ears) had normal I-V intervals
11% (5/47) had undetectable Wave I Due to profound hearing loss

15. Characteristics of patients at baseline ABR
Normal I-V interval
Prolonged I-V interval
(N=25)
(N=17)
Average Age (years)
9.7
(0.6-28)
6.7
(0.3-15)
Baseline cholesterol level (mg/dL)
116.7
(31-191)
108.4
(12-193)
Baseline 7-DHC
(mg/dL)
5.5
( )
10.5
( )
Baseline Sterol ratio (%) 15
( )
79.6
( )
* Ranges listed in parentheses

16. Wave I-V interval and hearing status
Prolonged I-V interval was not limited to individuals with hearing loss
59% (10/17 ears) with prolonged I-V interval had normal hearing
29% (5/17) with prolonged I-V interval had sensorineural hearing loss.

17. Longitudinal ABR
7 out of 11 patient’s ABR results were unchanged over time while on cholesterol and AquADEKs™
4 patients’ ABR results changed over time
2 moderately affected patients with normal/borderline baseline ABR’s developed prolonged ABR on cholesterol and AquADEKs™
1 mildly affected patient with normal baseline ABR developed a mildly prolonged ABR on cholesterol only
1 patient with prolonged baseline ABR had normal ABR on repeat testing after initiating cholesterol and AquADEKs™ treatment

18. Discussion- Hearing loss
Sensorineural hearing loss in Smith-Lemli-Opitz syndrome (SLOS) has only previously been described in case reports
In our study, baseline hearing loss was observed in 43% (20/47 ears)
19% (9/47 ears) showed sensorineural hearing loss
9% (4/47 ears) showed mixed hearing loss
This suggests that hearing loss is likely associated with SLOS
Patients with SLOS may benefit from regular hearing screenings

19. Discussion- ABR
Wave I-V intervals measure conduction time through the auditory brainstem pathway, from the auditory nerve to the inferior colliculus
36% (17/47 ears) had a prolonged wave I- V interval at baseline
Of those with prolonged intervals, 59% had normal hearing and 29% had sensorineural hearing loss
Prolonged conduction in the auditory pathway is likely associated with SLOS, and it is not limited to individuals with hearing loss

20. Discussion- Auditory outcomes in SLOS
The cause of hearing loss and prolonged I-V intervals in SLOS is unknown at this time
Potential contributing factors:
Cholesterol deficiency may be associated with decreased myelination in the central nervous system, membrane instability and/or altered functioning of ion channels
7-DHC oxidation leads to accumulation of oxysterols which are felt to decrease cell viability  could this occur in the auditory system too?

21. Discussion- Sterol Ratios
Sterol ratio calculation
[7-DHC + 8-DHC]/ cholesterol level x 100%
Average baseline sterol ratios by hearing status
Normal hearing (N=27 ears): 13.8
Sensorineural hearing loss (N=9 ears): 22.3
Mixed hearing loss (N= 4 ears): 283
Average baseline sterol ratios by ABR results
Normal I-V interval (N= 25 ears): 15
Prolonged I-V interval (N= 17 ears): 79.6

22. Discussion- Sterol Ratios
These data show that higher sterol ratios may be associated with a higher risk of hearing loss and prolonged wave I-V intervals
Use of sterol ratios in the clinical setting may prove beneficial in understanding SLOS patients’ severity of disease.

23. Discussion- Longitudinal data
No clear evidence that treatment with cholesterol and AquADEKs™ improves auditory outcomes over time
Potential explanations
Oxysterols may not play a role in auditory changes and AquADEKs™ may not have an effect on auditory outcomes
Also possible that AquADEKs™ may stabilize auditory outcomes from worsening over time, but not improve outcomes
? Sensitivity of ABR?

24. Summary
Hearing loss and prolonged neural conduction through the auditory pathway are seen in a subset of patients with Smith- Lemli-Opitz syndrome
Increased sterol ratios may be associated with higher risk of hearing loss and prolonged auditory neural conduction
Prolonged auditory neural conduction is not limited to individuals with hearing loss
No clear evidence that AquADEKs improves auditory outcomes

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