Analysis of screening results of FMR1, SMN1 and deafness-related genes in reproductive-age women in Mianyang area

doi:10.11958/20251484

Abstract

Abstract:

Objective To investigate the combined screening results and their clinical significance of Fragile X Mental Retardation 1 (FMR1) gene, Survival Motor Neuron 1 (SMN1) gene and hearing loss-related genes in Mianyang region of Sichuan province. Methods A cross-sectional study was conducted with 1 000 women of reproductive age who sought prenatal counseling. The CGG repeat number of the FMR1 gene was detected using the AmplideX technique, while SMN1 gene copy number variations were detected by real-time fluorescence quantitative PCR. The genotypes and allele frequencies of 15 loci in hearing loss-related genes were determined by melting curve analysis. Results In the 1 000 samples, 27 different CGG repeat numbers of FMR1 gene were detected, with the repeat range from 26 to 62. No full mutation carriers were found, but 2 cases (0.2%) of FMR1 gene premutation were identified. Among the SMN1 gene copy numbers, 981 cases (98.10%) had ≥2 copies, while 19 cases (1.90%) were SMA carriers with only 1 copy of the SMN1 gene. In the hearing loss-related gene screening, 43 carriers of hearing loss genes (4.30%) were identified. There were no significant differences in the distribution of CGG repeat numbers, SMN1 copy numbers and hearing loss-related gene carrier between the normal pregnancies and the miscarriages (P>0.05). Conclusion The study provides a preliminary understanding of the distribution of FMR1, SMN1 and hearing loss-related genes in the Mianyang region. It can serve as a basis for prenatal diagnosis and the prevention of birth defects in high-risk fetuses.

Key words: genetic counseling, miscarriage, FMR1 gene, SMN1 gene, deafness genes

CLC Number:

R715.5，R394

Figures/Tables 3

References 22

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基因名称	引物序列（5'→3'）
FMR1	上游：TGAGGCCGTGACGTCCGTTAGCCTTTGA
FMR1	下游：ATGCCGGATAGGACGGGCGACTTGC
FMR1- CGG	ACGCTGTAGTCTGTCCGCACTTGCGGCGGCGCGCCGGCC

基因名称	引物序列（5'→3'）
FMR1	上游：TGAGGCCGTGACGTCCGTTAGCCTTTGA
FMR1	下游：ATGCCGGATAGGACGGGCGACTTGC
FMR1- CGG	ACGCTGTAGTCTGTCCGCACTTGCGGCGGCGCGCCGGCC

基因	突变位点	检出数	检出率/%
GJB2	c.176 del 16杂合	3	0.30
	c.235 del C杂合	19	1.90
	299 del AT杂合	8	0.80
GJB3	c.538 C>T杂合	1	0.10
SLC26A4	c.2168 A>G杂合	3	0.30
	c.1975G>C杂合	1	0.10
	c.IVS7-2 A>G杂合	5	0.50
MT-RNR1	m.1555 A>G突变	3	0.30
合计		43	4.30

基因	突变位点	检出数	检出率/%
GJB2	c.176 del 16杂合	3	0.30
	c.235 del C杂合	19	1.90
	299 del AT杂合	8	0.80
GJB3	c.538 C>T杂合	1	0.10
SLC26A4	c.2168 A>G杂合	3	0.30
	c.1975G>C杂合	1	0.10
	c.IVS7-2 A>G杂合	5	0.50
MT-RNR1	m.1555 A>G突变	3	0.30
合计		43	4.30

组别	n		FMR1基因CGG重复数目
组别	n		正常范围（6~34）		正常范围高限（35~44）		灰区（45~54）		前突变（55~200）
正常妊娠组	733		550（75.0）		179（24.4）		2（0.3）		2（0.3）
流产组	267		205（76.8）		59（22.1）		3（1.1）		0（0）
χ²			4.084
组别		SMN1基因拷贝数				耳聋相关基因
组别		1		≥2		15个位点		未携带
正常妊娠组		16（2.2）		717（97.8）		37（5.0）		696（95.0）
流产组		3（1.1）		264（98.9）		6（2.2）		261（97.8）
χ²		1.178				3.839