Abstract
We present, in this paper, general formulae developed so as to permit the calculation of the recurrence risks for isolated cases of nonsyndromic deafness in the offspring of nonconsanguineous and consanguineous couples. We included, in all analyzed situations, the following factors: (a) a generic degree of parental consanguinity; (b) a variable proportion of environmental (non-genetic) cases of the defect, so that the formulae can be easily applied to populations with any epidemiological profile; (c) a variable number of normal sibs of the propositus. Besides presenting the logic and the detailed derivation of all original formulae, we present tables for immediate use, with the numerical values of the recurrence risks as a function of the variables mentioned above.
Highlights
Hearing loss is perhaps the sensorial defect more frequently found in humans, constituting a major public health problem, as it affects more than 1/1000 of the world population
In Brazil, for instance, the frequency of nonsyndromic congenital deafness ranges at four in 1000 births, 16% of which are of genetic etiology (Braga et al, 1999)
The recurrence risks for isolated cases of deafness were evaluated taking into account: the complete structure of the nuclear family, including the number of normal sibs of the propositus; in cases of parental consanguinity, a generic coefficient of inbreeding (F); and variable rates of environmental cases of the defect
Summary
Hearing loss is perhaps the sensorial defect more frequently found in humans, constituting a major public health problem, as it affects more than 1/1000 of the world population. Even in a country with a medical, sanitary and economic development profile like Brazil, where the environmental cases of the defect predominates (84%), the frequency of genetic cases (16%) is still significant (Braga, 1999); it is important that the families of affected individuals receive counseling regarding the recurrence risks of deafness in sibs, children, and other close relatives.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
