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Rupture of intracranial aneurysms (IAs) causes subarachnoid hemorrhage (SAH), a devastating condition with high mortality and morbidity. Genetic factors as well as environmental factors play an important role in the pathogenesis of IA and SAH. We first performed a genome-wide linkage study of IA in 104 Japanese affected sibpairs in which positive evidence of linkage was found at 5q22-31, 7q11, and 14q22. Other genome-wide linkage studies have identified genetic loci for IA on 19ql3.3 in a Finnish study, 17cen, 19ql3, and Xp22 in a Japanese study, on 2p13, 1p34.3-36.13, 11q24-25,14q23-31, and 5p15.2-14.3 Iq34.3 with the use of large families in which IA is inherited as a simple Mendelian trait. We extensively analyzed a 4.6 Mb linkage region around D7S2472 on 7q11 by genotyping 168 single nucleotide polymorphisms (SNPs). SNP haplotype-based association studies revealed a susceptibility locus for IA on a single LD block covering the 3'-untranslated region of ELN and the entire region of LIMK1. We have identified the ELN 3'-UTR G (+639) C SNP as a genetic susceptibility allele for IA, which occurs in an at-risk haplotype containing two functional SNPs that reduce the transcript levels of ELN and LIMK1, respectively. Other candidate genes have been studied by association analysis using cases and controls in different populations, but no specific genes have so far been identified as showing a clear association with IA. Further genetic association and linkage studies with more large-scale populations are needed to unravel the genetic risk factors of IA. These studies should also be combined with investigations of gene function.

Familial essential myoclonus and epilepsy (FEME) is hereditary epileptic disorder characterized by adult-onset, tremor-like postural myoclonus, spontaneous myoclonus, infrequent convulsive seizures and benign clinical course. Benign adult familial myoclonic epilepsy (BAFME) and Familial adult myoclonic epilepsy (FAME) are autosomal dominant myoclonic epilepsy, and these clinical picture are similar to that of FEME. The causative gene of BAFME and that of FAME were mapped 8q23.3-24.1, but these two candidate area had not overlapped territory. So, to resolve the problem in identity of these three disease concepts and to recognize molecular mechanism of FEME, I started cloning of the causative gene. As the first step clinical information from twenty-seven Japanese FEME families was collected and then detailed clinical genetic analyses including segragation ratio, sex ratio, penetrance, presence of anticipation and distribution of age at onset were conducted. All the families showed complete genetic penetrance without skipping of generation. The mode of inheritance was concluded to be autosomal dominant one. Anticipation of age at onset and potentiation of phenotype were not observed. Distribution of age at onset was unimodel. The collected families had homogenous clinical symptom and age onset, so these families were suitable as families for linkage analysis. Based on the result of these analyses, Given little evidence supporting genetic anticipation that is frequently observed in neurodegenerative diseases caused by expansions CAG repeats, I selected and a standard positional cloning strategy to identify the causative gene. Linkage analysis was performed on twenty-one FEME families with informed consent. Pair-wised linkage analysis revealed the highest cumulative maximal lod score of 9.31 at GATA68H01(θ=0). Observation of obligate recombination events narrowed the candidate region to a 5.1-cM region between D8S1122 and D8S1112. This region had widely overlapped territory on that of BAFME, and not of FAME. These results suggest that FEME and BAFME are genetically identical disorder and the candidate region for the FEME/BAFME gene is located the 3.37-cM region between D8S1122 and D8S1694

Using 10,473 barley accessoins and 16,480 gamma-ray lines, root fluorescence mutants which have been reported in order crops, such as soybean, were screened. No spontaneous mutant was found,but an artificial mutant whose root tips emitted a pink glow under ultraviolet light was obtained by the gamma-ray irradiation. The mutant was controlled by a recessive gene named frp 'fluorescent reaction-pink'. It was poor growth and was lethal. The transmissoin rate of the mutant gene was about 80% of that of the normal allele. Thus the segregation in the heterozygous populations was ca. 4 normal to 1 mutant. The frp gene is located close to gl-3, 'glossy leaf-3' on the 4H chromosome., オオムギ10,473品種およびコムギ1,140品種を供試して根の蛍光変異体を検索したが、変異体を見出すことはできなかった。オオムギ品種ふじ二条にガンマー線を3世代にわたって90KR照射したM8世代16,480系統の中から根端が紫外線によってピンクに発色する変異体が3系統得られた。これらは同一の突然変異に由来する姉妹系統の可能性が高い。この蛍光変異体は劣性1遺伝子frp（fluorecent reaction pink）に支配される。frpは4H染色体のgl-3近傍に座乗し、その伝達率は正常型の対立遺伝子に比べて0.8程度と低い、frpは致死遺伝子であるがヘテロ維持が可能である。

Machado-Joseph disease (MJD) is an autosomal dominant, multisystem neurodegenerative disorder involving predominantly cerebellar, pyramidal, extrapyramidal, motor neuron and oculomotor systems. Although it was first reported in families of Portuguese-Azorean descent, MJD has also been described in non-Azorean families from various countries, being one of the most common hereditary spinocerebellar degenerations. With the use of highly polymorphic microsatellite DNA polymorphisms, we have assigned the gene for MJD to the long arm of chromosome 14 (14q24.3-q32.1) by genetic linkage to microsatellite loci D14S55 and D14S48 (multipoint lod score Zmax=9.719).

The inheritance and geographical distribution of the phenol reaction in rice has been investigated intensively. On the other hand, in the case of barley, almost all of the varieties show positive reaction to phenol, and inheritance study of the trait has not yet been reported. We investigated the phenol reaction of ca. 5,000 barley varieties preserved at the Barley Germplasm Center of Okayama University to find about 30 varieties which show a negative reaction to the phenol. These varieties are mainly from Southwest Asia. The reaction of awn was sharpest at all parts of the plant including seeds. The positive reaction must be the prototype of barley, because Hordeum spontaneum, a possible ancestor of the cultivated barley, shows positive reaction. Inheritance and linkage studies were conducted using varieties with negative reaction and linkage testers with positive reaction. Phenol reaction was dominant and showed a clear 3:1 segregation ratio in the F2 populations, indicating the trait was controlled by a single dominant gene Ph(phenol reaction). Linkage study revealed that Ph was linked with four marker genes(three loci) on the chromosome 2 and independent of 13 other marker genes located on the chromosomes except chromosome 2. Ph may be a useful marker gene and an interesting material for molecular-biological studies., オオムギの芒ではフェノールを酸化する酵素の活性が強くが、極めて少数の品種では芒のフェノール着色が見られない。本研究では芒のフェノール着色反応の遺伝性を解析した。結果は次の通り。1）芒のフェノール着色反応は優性遺伝子ph（phenol reaction）によって支配されている。2）Phは第2染色体にe-Ph-liの順で配列している。3）芒、穀皮および果実（果皮）の反応が一致しない場合があるが、これが実験誤差か、それぞれの組織で別個の遺伝子が作用していることによるのかは確認を要する。

A mutant which devolops an extremely shortened flag leaf and shorter upper leaves was obtained from the progeny of 90 KR of gamma-ray irradiated Fuji Nijo, a malting barley variety. This mutant was controlled by a single partial dominant gene named Sul (short upper leaves). The character expression and the inheritance of the gene were investigated in this study. Sul shortened the flag leaf and upper several leaves and uppermost internode length, while it did not affect the length of spike, lower leaves and the second or lower internodes. A reciprocal translocation of the chromosomes was observed in this mutant line, and the Sull gene was linked with the V (two-rowed) gene on chromosome 2, and also linked with the breaking point of the reciprocal translocation. Small leaf area caused by the Sull gene might reduce the mutual shading and the transpiration of the leaf canopy at the later growth stages., 二条オオムギ品種ふじ二条にガンマー線を3代にわたって合計90KR累代照射した後代から上位の数葉が短縮し、特に止葉は痕跡的に短くなる変異体を見出し、その形質表現と遺伝性を解析した。1）この変異体では基部の数枚の葉身の長さは原品種と変わらず、上位の数葉、特に止葉が強く短縮する。穂長および小穂段数は原品種と変わらない。2）この変異体は不完全優性の主働遺伝子Sul（short upper leaves上位葉短縮型）に支配される。3）Sul遺伝子は第2染色体に座乗するν/V（条性）遺伝子と連鎖し、また相互転座点と密接に連鎖している。4）この変異体は登熟期における葉面積が小さいので相互遮蔽が少なく、また収穫指数が高まって多肥密植栽培で多収となる可能性があり、また、蒸散量が少なく、半乾燥条件に適応することが期待される。

Recent advances in molecular genetics have made it possible to identify genes for various hereditary neurodegenerative disorders. The approach, which is now called positional cloning, consists of two steps. The first step is to determine the chromosomal localizations of disease genes by linkage analyses. The second step is to determine the causative genes themselves. As many microsatellite markers have been described, the linkage analysis can now be performed far more effectively. Development of new technologies including pulsed-field gel electrophoresis and cloning of several hundred kilobases of genomic DNA using yeast artificial chromosomes have also brought new effective strategies for the positional cloning. Our laboratory has been involved in identification of genes for neurologic diseases including adrenoleukodystrophy and various forms of spinocerebellar degenerations. Application of microsatellite polymorphisms for the linkage analysis of early-onset ataxia associated with hypoalbuminemia (EOAHA) was described. As a new technology for positional cloning, an improved hncDNA (heterogenous nuclear RNA-complementary DNA) cloning method was described. Our approaches toward the identification of the causative genes for these diseases and better understanding of the molecular mechanisms of neurodegenerative diseases are discussed.