Preimplantation genetic diagnosis and deafness

Prenatal Diagnosis and Pregnancy Termination in Jewish and Muslim Women with a Deaf Child in Israel

Deafness is the most common sensory disability in humans, influencing all aspects of life, However, early diagnosis of hearing impairment and initiating the rehabilitation process are of great importance to enable the development of language and communication as soon as possible. We examined the differences in attitudes towards performing prenatal invasive tests and pregnancy terminations in Jewish and Muslim women in Israel due to deafness. Overall, 953 Israeli women, aged 18-46 years with a mean age of 32.0 (SD = 7.12), were enrolled. Of those, 68.7% were city dwellers and 31.3% were village dwellers, and 60.2% were Muslim women and 39.8% were Jewish women. All participants had a child with a hearing impairment or deafness. The group with no genetic hearing loss performed more prenatal invasive tests and pregnancy terminations than those with genetic hearing loss in both ethnic groups. Jewish women performed more invasive prenatal tests and, consequently, a pregnancy termination. Secular Jewish women more frequently underwent pregnancy terminations due to fetal deafness. Further genetic counseling and information concerning IVF and PGD procedures should be provided to the Muslim population.

Identification of novel microsatellite markers flanking GJB2 gene in order to use in preimplantation genetic diagnosis of hearing loss: A comparison of whole-genome amplification and semi-nested PCR

Hearing loss is the most prevalent sensorineural disorder which can be caused by genetic factors in more than half of the cases. GJB2 mutations with the frequency of 18.7% are the most common cause of autosomal recessive non-syndromic hearing loss (ARNSHL) in the Iranian population. The aim of the current study was to genotype 100 healthy individuals for eight microsatellite markers flanking the GJB2 gene, and to study markers on ten blastomeres using semi-nested PCR and Whole-genome amplification (WGA). All microsatellite markers within 1 Mb flanking the GJB2 gene were identified. From the identified markers, four with potentially high heterozygosity values were selected. The heterozygosity indices of four newly discovered markers and four previously reported markers were calculated. The markers and the GJB2 gene were also validated on single lymphocytes and blastomeres. Totally, 77 alleles were observed in eight loci. D13S046 showed the highest polymorphism and D13S141 showed the lowest. The observed heterozygosities of all markers, except D13S141, were higher than 50%. All single cells were genotyped successfully by the two techniques. Our findings indicate a high degree of polymorphism of the selected markers. Due to the high rate of successful amplification of markers in all ten blastomeres and the low level of allelic drop out (ADO), a combination of these eight microsatellite markers in conjunction with direct mutation detection is suggested for performing preimplantation genetic diagnosis (PGD) of hearing loss due to GJB2 mutations.

Deafness, a Social Stigma: Physician Perspective

Hearing is an essential sensory sense of an individual for development of speech which is crucial for verbal communication and personality development. It is the second most common form of disability after loco motor disability in India. Disabling hearing loss is more than 40 dB hearing loss in better ear in a person more than 15 years of age and greater than 30 dB hearing loss in better hearing ear below 14 years of age. WHO estimated 360 million individuals in the world with disabling hearing loss, out of which 91 % are adults and only 9 % are children. Early and accurate identification of birth asphyxia, hyperbilirubinemia, auditory neuropathy Presbyacusis and avoiding noise pollution and discouraging use of mobile phone, tobacco chewing/smoking, in those who are prone to deafness, an intervention is a must to decrease deafness from our society. Deafness prevention can only be possible with mutual cooperation with dedication of different medical and non-medical personnel and also by helping the persons with deafness. We have to focus not only on the children but also on senior citizens as most alarming, up to 40 %, incidence of deafness is in senior citizens above the age of 75 years. Timely cure and preventive measures are essential for better socio-economic state of the country. By helping the persons with deafness, we will not only be doing a great service to the Nation but also to the society at large.

Preimplantation genetic diagnosis: its role in prevention of deafness

Deafness is a global problem. In India deafness ranges from 4 % in urban to 11 % in rural and slum areas, out of which 50 % is conductive hearing loss hence curable. Genetic transmission accounts for 50 % of the cases of congenital deafness, and of these, around 30 % are syndromic and 70 % are non-syndromic. Genetic counseling is going to make aware the parents of all appropriate treatments. Preimplantation genetic diagnosis can help to have a baby free from genetic deafness. Procedure is almost safe, harmless, non-invasive and ethically acceptable. While Amniocentesis is a non-invasive method, prenatal genetic testing through Chorionic villous sampling is invasive. The connexin 26 (CX26W 24X) mutations are the most common cause of non-syndromic hearing loss and easy to identify by polymerase chain reaction. There is always co-morbidity after cochlear implantation and the person remains handicapped while baby after PGD shall be having healthy normal life and person prone to environmental factors may be counseled and guided to prevent deafness in next generation. Public must be made aware of noise pollution, tobacco toxicity and consanguinity. The Obstetrician and Pediatrician apart from ENT surgeon should be involved to prevent antenatal or neonatal deafness.