Inheritance Of Genetic Markers Research Articles

Audiologic Aspects of the Search for DFNA20: A Gene Causing Late-Onset, Progressive, Sensorineural Hearing Loss

The purpose of this research was to identify the gene responsible for a novel form of nonsyndromic, late-onset, bilateral, progressive, sensorineural hearing loss in a Michigan family of English descent. This report describes the audiologic aspects of the search. Fifty-eight members of the family served as subjects for the study. Family pedigree information was gathered from family interviews, family records, birth and death registration records and census data. Audiologic evaluation was used to describe the hearing loss (phenotype) and classify family members as affected or unaffected based on hearing status. These data then were used in a linkage analysis, a process in which the inheritance of a trait is compared with the inheritance of genetic markers and statistically significant associations are sought. The team mapped the hearing loss to the long arm of chromosome 17 at band 17q25. The pattern of inheritance is autosomal dominant. The search for the gene is continuing using a candidate gene approach. The hearing loss demonstrated by this mid-Michigan family is a novel form of nonsyndromic, genetic, late-onset, bilateral, progressive, sensorineural hearing loss. The locus of the gene, the 20th for autosomal dominant hearing loss, is at band 17q25 of chromosome 17.

The inheritance of genetic markers in microspore-derived plants of barley Hordeum vulgare L.

Biochemical, molecular and morphological markers have been used to monitor the segregation of alleles at major gene loci in microspore-derived lines of four spring barley crosses and their parents. Significant deviations from the expected Mendelian ratios were observed for four of the ten markers studied in the cross. Distorted ratios were associated with loci located on chromosomes 4H and 6H. The differential transmission of alleles was in favour of the responsive parent (Blenheim) used in the anther culture studies. For the α-Amy-1 locus on chromosome 6H, the preferential transmission of Blenheim alleles was most pronounced in the haploid regenerants that were colchicine treated. These results are discussed in relation to the genetic control of androgenetic response in barley and with respect to the exploitation of another culture in barley improvement.

Inheritance of genetic markers from two potato dihaploids and their respective parent cultivars

In the first inbred generation (I1) of cv. Black 4495 a dark green, slowly growing mutant (coded ds) was found, whereas the I1 of its self-compatible dihaploid, B16, comprised this ds mutant and in addition the mutants virescens (v) and yellow margin (ym). The occurrence of ds and ym might trace back to diploid S. phureja, one of the ancestors of Black 4495. No lethal mutants were observed in I1 of B16. Analysis of I1 of cv. Gineke revealed a simplex condition for virescence and either duplex or triplex heterozygosity for one lethal gene. On the other hand, the I1 of its dihaploid, G254, segregated for virescence and for three different lethal genes. It is shown that both in B16 and in G254 homozygosity of an S-bearing translocation causes early death of embryo and endosperm, thus preventing seed development. From this study it appeared that the three lethal genes from G254 affect germination rate of the seeds. The genotypes at 11 loci of B16 and G254 are presented.