[Prenatal genetic test and clinical guidance for 213 hereditary deaf families]

Abstract

Objective: To summarize the workflow, strategy and experience of prenatal genetic test for deafness based on the 6-year clinical practice.

Methods: There were 213 families who received prenatal test from 2005 to 2011. Among the 213 families, 205 families had had one deaf child, including 204 couples with normal hearing and one couple of the deaf husband and normal wife, 8 families including 6 couples with normal hearing and 2 deaf couples, had no child before test. Genomic and mitochondrial DNA of each subject was extracted from whole blood. The etiology and recurrent risks in 212 families were confirmed by means of the genetic test of GJB2, SLC26A4 and mtDNA 12sRNA, but one family carried POU3F4 c.647G > A heterozygous mutation causing X-linked hereditary hearing impairment confirmed by pedigree study. The prenatal test was carried out during the pregnancy of all mothers from 11 to 30 weeks, and the following genetic information and counseling were supplied based on the results.

Results: The recurrent risk was 25% in 209 families, including 204 families with one deaf child and 5 families without child, among which all couples were GJB2 or SLC26A4 mutation carriers and deaf children were caused by homozygous or compound GJB2/SLC26A4 mutations; The recurrent risk was 50% in 3 families, the father and his child in one family had compound SLC26A4 mutations and the mother with heterozygous SLC26A4 mutation, the wife had POU3F4 c.647G > A heterozygous mutation in another one family, and the husband with compound SLC26A4 mutations and the wife with mtDNA A1555G mutation and heterozygous SLC26A4 mutation simultaneously happened in the rest one family; The recurrent risk was 100% in one family of the deaf couple who were both found to carry homozygous or compound GJB2 mutations, and the deaf wife got pregnant by artificial insemination with the sperm from the local Human Sperm Bank. 226 times of prenatal test were applied in all 213 families that 11 families of them received prenatal test twice, and one family received three times. 46 times of prenatal testing showed that the fetuses carried parental mutations simultaneously or the same mutations with probands; while 180 times of prenatal test showed that the fetuses carried only one parental mutation or did not carry any mutation from parents. The following visit showed that all of these 180 families had given birth to babies who were all revealed to have normal hearing by new born hearing screening test.

Conclusions: Prenatal diagnosis for deafness assisted by genetic test can provide efficient information about offspring's hearing condition, and the normative workflow and precise strategy highly guarantee the safe and favorable implementation of prenatal diagnosis.