Genetic and clinical analysis of nonsyndromic hearing impairment in pediatric and adult cases

Amino Acid	Nucleotide	Number of Affected Alleles		Number of Alleles	Category
		Homozygous	Heterozygous
V27I	79G>A	27	90	144	polymorphism
E114G	341A>G	11	69	91	polymorphism
V37I	109G>A	1	11	13	polymorphism
I203K	608T>C	1	8	10	polymorphism
T123N	368C>A	0	3	3	polymorphism
G4D	11G>A	0	1	1	missense
11stop	30-35delG	1	1	3	deletion/frameshift
R32C	94C>T	0	1	1	missense
E47X	139G>T	0	1	1	missense
59stop	176-191del16	0	1	1	deletion/frameshift
W77X	231G>A	0	1	1	missense
79stop	235delC	15	15	45	deletion/frameshift
Q80R	239A>G	0	1	1	missense
299-300delAT	299-300delAT	3	4	10	deletion/frameshift
S139N	416G>A	1	0	2	missense
T18I	53C>T	0	1	1	novel sequence variation
D50N	148G>A	0	1	1	novel sequence variation
Y38C	203A>G	0	1	1	novel sequence variation
T86R	257C>G	0	1	1	novel sequence variation
G160S	478G>A	0	1	1	novel sequence variation

Table 2

Frequency of the GJB2 gene variations in patients with NSHI.

Amino Acid	Nucleotide	Number of Alleles	Frequency (%)
E47X	139G>T	1	1.52
R32C	94C>T	1	1.52
G4D	11G>A	1	1.52
W77X	231G>A	1	1.52
59stop	176-191del16	1	1.52
Q80R	239A>G	1	1.52
S139N	416G>A	2	3.03
11stop	30-35delG	3	4.55
299-300delAT	299-300delAT	10	15.15
79stop	235delC	45	68.18
Total		66	100.00

The frequency refers to the number of the mutant allele of a general/all mutant alleles (total number 66).

Mutation rates for patients with NSHI classified by age at first hospital visit.

Table 3

Mutations status in pediatric cases of NSHI categorized by age at the first hospital visit.

Mutation Status	Infants (n = 72)	Preschool (n = 54)	School Age (n = 70)	χ² Test	p Value
GJB2: - mutation - no mutation	16 (22.22%) 56 (77.78%)	14 (25.93%) 40 (74.07%)	15 (21.43%) 55 (78.57%)	0.384	0.826
mtDNA A1555G/C1494T: - mutation - no mutation	1 (1.39%) 71 (98.61%)	2 (3.70%) 52 (96.30%)	6 (8.57%) 64 (91.43%)	4.314	0.143**

** Fisher’s exact test

Mutation rates for patients with NSHI classified by age at onset of deafness.

Table 4

Mutation status in pediatric cases of NSHI categorized by age at onset of deafness.

Mutation Status	Infants (n = 186)	Preschool (n = 21)	School Age (n = 30)	χ² Test	p Value
GJB2: - mutation - no mutation	44 (23.66%) 142 (76.34%)	2 (9.52%) 19 (90.48%)	3 (10.00%) 27 (90.00%)	4.685	0.096
mtDNA A1555G/C1494T: - mutation - no mutation	18 (9.68%) 168 (90.32%)	2 (9.52%) 19 (90.47%)	5 (16.67%) 25 (83.33%)	1.363	0.502**

** Fisher’s exact test

Table 5

Mutation status in pediatric cases of NSHI cases by pre-lingual or post-lingual onset of deafness.

Mutation Status	Pre-lingual Deafness (≤3 years)	Post-lingual Deafness (>3 and <18 years)	χ² Test	p Value
GJB2: - mutation - no mutation	44 (23.66%) 142 (76.34%)	5 (9.80%) 46 (90.20%)	4.683	0.031
mtDNA A1555G/C1494T: - mutation - no mutation	18 (9.68%) 168 (90.32%)	7 (13.73%) 44 (86.27%)	0.695	0.404

Table 6

Distribution of age of onset in patients with the GJB2 gene and mtDNA mutations.

Mutation Status	Total	Age at Onset			χ² Test	p Value
		≤1 year	>1 and ≤3 years	>3 years
GJB2 gene	49	32 (65.31%)	11 (22.45%)	6 (12.24%)	13.383	0.001
mtDNA mutations	30	8 (26.67%)	9 (30.00%)	13 (43.33%)

Table 7

Comparison of the degree of hearing loss between patients with the GJB2 gene and mtDNA mutations.

Mutation Status	Total	Degree of Hearing Loss				p Value
		Mild	Moderate	Severe	Profound
GJB2 gene	49	3 (6.12%)	5 (10.20%)	9 (18.37%)	32 (65.31%)	<0.001**
mtDNA mutations	30	1 (3.33%)	15 (50.00%)	0 (0.00%)	14 (46.67%)

** Fisher’s exact test

Table 8

Comparison of the degree of hearing loss by grading standard of 22 patients with mtDNA mutations.

Grading Standard	Degree of Hearing Loss
	Mild	Moderate	Moderate to Severe	Severe	Profound
Guidelines [11]	1	11	‒	3	7
ISO-1964aa bb	5	6	5	1	5
ISO-1997	1	8	‒	5	8
0.25-8.0 kHz	0	6	7	2	7
1.0-4.0 kHz	0	4	5	7	6
4.0-8.0 kHz	0	0	0	7	15

aa Compared with 4.0-8.0 kHz p <0.001.

bb Fisher’s exact test.

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DOI: https://doi.org/10.1515/bjmg-2016-0005 | Journal eISSN: 2199-5761 (formerly 1311-0160) | Journal ISSN: 1311-0160

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Language: English

Page range: 35 - 42

Published on: Aug 2, 2016

Published by: Macedonian Academy of Sciences and Arts

In partnership with: Paradigm Publishing Services

Keywords:

Genetic testing,

GJB2 gene,

mtDNA A1555G/C1494T,

Nonsyndromic hearing impairment (NSHI)

Related subjects:

Medicine,

Basic medical science,

Basic medical science, other

© 2016 J Xing, X Liu, Y Tian, J Tan, H Zhao, published by Macedonian Academy of Sciences and Arts
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Volume 19 (2016): Issue 1 (June 2016)