Genetic studies on the Gc subtypes

Summary Gc subtypes were determined by immunofixation isoelectric focusing. In a family study involving 93 families with a total of 176 children, a three-allele model with six genotypes was confirmed. The distribution of Gc subtypes was studied in three populations from Europe and in a sample of Druzes from Northern Israel. Three new variant Gc types were observed.     

Genetic studies on some Nepalese populations

Populations living in two different regions of Nepal have been studied. The first region (the Kali Gandaki valley) is inhabited mainly by Magars, Gurungs, Thakalis and Chetris. It has been found that they exhibit different ABO gene frequencies though living in very close areas and often in the same villages. Thus they are still genetically different entities besides being ethnically distinguishable from each other.The second region examined in the present survey (the Solu Khumbu) is inhabited by Sherpas. They were studied for markers not analysed in a previous research, namely for ABO, UMPK, PGD, GLO and LDH.     

Genetic studies on temperature sensitive nonsense suppression

Summary Temperature sensitive suppression of nonsense mutations has been obtained, in E. coli, by inducing a mutation in the suppressor gene su-4, a structural gene for a tyrosine tRNA. In this mutant while no suppression is detectable at 42°C it is always present at lower temperatures. This temperature sensitivity is amenable to a reversible inactivation of the product of the su-4 gene.     

Genetic studies on Rhizobiophage 16-3

Summary A number of temperature-sensitive (ts) and lysis-deficient mutants were isolated from a bacteriophage of Rhizobium meliloti. The ts mutants were grouped by complementation. Functions were classified in relation to the eclipse and latent period. A genetic map of about 40 units was derived from crosses. The genes on the chromosome of the phage are arranged in the order of their presumed functions during the phage growth. They are located on the chromosome in sequence: immunity-early-late-lysis genes.Abbreviations Ant altered antigene - C immunity gene - h host range - K velocity constant of antiphage serum - L lysis gene - m.o.i. multiplicity of infection - NTG N-methyl-N-nitro-Nnitrosoguanidine - P.F.U. plaque forming unit - Rh.41 Rhizobium meliloti strain 41 - ti thermo-inducible - ts temperature-sensitive     

Genetic studies on seedling vigour in sesame

Genetic studies were carried out on seedling and agronomic characters amongst 50 sesame genotypes to estimate the genetic variation, determine the relationships amongst the characters and identify rapidly growing genotypes with vigorous seedling growth. The contribution of genetic variance was highest for the two mature characters, days to first flower (95.6%) and number of nodes to first flower (95.2%), and was medium/high (50–75%) for most of the seedling characters. Strong positive genetic correlations were obtained between various cotyledon and early leaf characteristics measured at 20 days after sowing. Based on these results several genotypes were identified as having rapid seedling growth and these could form an initial gene pool to provide material for screening for tolerance to sesame flea beetle.     

Genetic studies on southeastern Bantu of Mozambique

Summary Gene frequencies of 9 genetic markers are presented in a group of 4 Bantu tribes. With the exception of AK and LDH, these genetic markers are polymorphic, being thus useful in the study of anthropological relationships among the major Negroid populations in Africa.

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Zusammenfassung Die Genhäufigkeiten von 9 genetischen Markern wurden in einer Gruppe von 4 Bantu-Stämmen bestimmt. Mit Ausnahme von AK und LDH zeigen diese Marker einen Polymorphismus. Deshalb sind die für das Studium anthropologischer Beziehungen zwischen den hauptsächlichen Neger-Populationen in Afrika geeignet.

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Supported in part by Public Health Grant AM 09745.     

Genetic background of apparently idiopathic sporadic cerebellar ataxia

Disease-causing mutations have been identified in various entities of autosomal dominant ataxia and in Friedreich's ataxia. However, no molecular pathogenic factor is known to cause idiopathic cerebellar ataxias. We investigated the CAG/CTG trinucleotide repeats causing spinocerebellar ataxia types 1, 2, 3, 6, 7, 8 and 12, and the GAA repeat of the frataxin gene in 124 patients apparently suffering from idiopathic sporadic ataxia, including 20 patients with the clinical diagnosis of multiple system atrophy. Patients with a positive family history, a typical Friedreich phenotype, or symptomatic ataxia were excluded. Genetic analyses uncovered the most common Friedreich mutation in 10 patients with an age at onset between 13 and 36 years. The SCA6 mutation was present in nine patients with disease onset between 47 and 68 years of age. The CTG repeat associated with SCA8 was expanded in three patients. One patient had SCA2 attributable to a de novo mutation from a paternally transmitted, intermediate allele. We did not identify the SCA1, SCA3, SCA7 or SCA12 mutation in idiopathic sporadic ataxia patients. No trinucleotide repeat expansion was detected in the MSA subgroup. This study has revealed the genetic basis in 19% of apparently idiopathic ataxia patients. SCA6 is the most frequent mutation in late onset cerebellar ataxia. The frataxin trinucleotide expansion should be investigated in all sporadic ataxia patients with onset before age 40, even when the phenotype is atypical for Friedreich's ataxia.