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More than 45 years have passed since Kawasaki disease(KD) was firstly described. Although the infectious agent possibly triggering the disease has not been identified, a total of 6 susceptibility genes/loci for KD have been identified through genome-wide studies. Although association of these loci are robust and has been confirmed in multiple populations, these can explain only a part of genetic background of the disease. Further investigation of genetic factors including unidentified common and rare variants as well as personal mutations contributing to individuals' susceptibility to the disease and risk for severer manifestation should be warranted and multicenter collaboration of collecting patients' subjects and information is essential for current and future genetic study of KD.

Technologies associated with massively parallel sequencing have evolved rapidly over the last several years, making it possible to cost-effectively sequence the whole human genome and exome in a short period of time. These technologies are expected to bring about a better understanding of genetic components underlying monogenic diseases, as well as diseases inherited in a non-Mendelian fashion. They will eventually cause a paradigm shift in clinical practice, where the diagnosis and decision-making for appropriate therapeutic procedures is based on the "personal genome". In this review, we outline some of our recent efforts in the Medical Genome Center at the University of Tokyo Hospital, including an identification of the causative gene for a Mendelian disease (posterior column ataxia with retinitis pigmentosa), an approach to uncover susceptible genes for a non-Mendelian disease (Parkinson disease), and an application of exome sequencing for the molecular diagnosis of a disease with vast genetic heterogeneity (hereditary diffuse leukoencephalopathy with spheroids). We also discuss the advantages and limitations of these emerging technologies.

Miyake's disease (occult macular dystrophy: OMD) was first described by Miyake et al. to be a hereditary macular dystrophy without visible fundus abnormalities. Patients with OMD are characterized by a progressive decrease of visual acuity with normal appearing fundus and normal fluorescein angiograms. The important signs of OMD are normal full-field electroretinograms (ERGs) but abnormal focal macular ERGs. In 2010, we found that dominant mutations in the RP1L1 gene were responsible for OMD by a linkage analysis of two OMD families, and recently, the same mutations were known to cause OMD in non-Japanese patients. Here, we describe how this disorder has been discovered and the causative gene was found by Miyake's group, together with the detailed characteristics of OMD.

With the throughput of next-generation sequencers, even whole genome analysis is a reality. Traditionally, it was important to collect as many samples as possible and to perform sequence analysis of many genes in candidate regions. There has been a paradigm shift in the era of next-generation sequencing; to reveal the significance of raviants produced by next-generation sequencers rather than just to perform sequence analysis becomes the key to elucidate causes of disorders. We performed target capture and next-generation sequencing analyses of a small consanguineous family in which only two members were affected by posterior column ataxia with retinitis pigmentosa (PCARP). We successfully identified a causative mutation in FLVCR1 which cosegregated with the disease. The fact that we could identify the causative gene even from a small family means that the advent of next-generation sequencers has brought us to a next-generation analysis on hereditary disorders. In the near future, many causative genes of hereditary neurodegenerative disorders particularly with small number of affected members will be revealed, which must provide considerable insights into pathogenesis. Approaches utilizing bioinformatics to further narrow down the numerous variations produced by next-generation sequencers are demanded in order to study remaining small families, or sporadic diseases.

The factors for the individual differences include both genetic and environmental factors. Genome-wide association study (GWAS) was first developed in RIKEN in 2002 and has now become a major research technology. In GWAS, the associations between genomic variations and the variations in the traits are analyzed by statistical genetics. As many as 100,000-2,500,000 polymorphic loci are distributed over the whole genome, and the associations between either genotypes or alleles and the phenotypes are analyzed. The phenotypes are either diseases, physical data or clinical laboratory data, and it was found that the targets of the available drugs are often included in the genes that were found to be associated with the diseases. These data indicate that the results from GWAS may be applied to the development of new drugs (GWDD; genome-wide drug discovery). GWAS started to influence pharmacogenomics in which the associations between genomic variations and drug reactions are studied. Genes associated with statin-induced severe muscle damage, efficacy of interferon for C-type hepatitis, ribavirin-induced hemolytic anemia and carbamazepine-induced severe skin eruption were found by GWAS. In 2010, "Guidelines for clinical studies and tests in which pharmacogenomics is applied" was released as a draft.

Since the whole human genome sequence has become available, the methods to search for genes of diseases or drugs responses (traits) have changed dramatically. The former approach designated as "candidate gene approach" is now dominated by "genome-wide approach". In the former approach, researchers search for the genes based on the functions using biochemistry and molecular biology; however, in the latter approach, the genes are searched for by the genetic and statistical methods. Initially, monogenic diseases were the targets of the researches; however, polygenic diseases and drug responses have become the targets. Parametric linkage analysis was quite useful for identifying responsible genes for monogenic diseases. Genome-wide association study (GWAS) has been introduced for the identification of the genes for polygenic diseases and drug responses. GWAS was first introduced from 2002 to 2004 in Center for Genomic Medicine, RIKEN but has expanded rapidly to other countries including US, Europe and Asian countries from 2005. In Nature Genetics journal, about half of the articles published recently include the data from GWAS studies. Both qualitative and quantitative traits have been analyzed by GWAS. Qualitative traits include diseases and drug responses and quantitative traits include physical measures and clinical laboratory test values. Recent reports about the association between drug responses and genes have clarified many important pharmacogenomic associations. For these data to be analyzed efficiently and used appropriately; however, guidelines for researches and clinical tests concerning pharmacogenomics (PGx) are necessary. "Guideline for pharmacogenomic test" was issued in 2009 and, in addition, an extended guideline covering various fields is now being discussed.

Ossification of posterior longitudinal ligament of the spine (OPLL) is a polygenic disease caused by genetic and environmental factors. The genetic factor is composed by multiple susceptibility genes. Studies for the OPLL susceptibility genes mainly using linkage and association analyses are in progress mainly in Japan, and several genes have been reported. This paper reviewed the recent progress of the OPLL genetic study.

Purpose: High resolution (four-digit) allele genotyping was used to determine the association of the HLA-A and -B alleles with Behçet's disease (BD) in Japanese patients. We also analyzed our results for the association of these alleles with the individual clinical features of BD., Subjects and Methods: We enrolled 389 Japanese BD patients and 254 healthy controls in this study. Genotyping of the HLA-A, -B alleles was performed by the PCR-SSOP-Luminex method and the phenotype frequencies of the HLA-A, and -B alleles were estimated., Results: Some HLA-A and -B alleles were significantly associated with BD. When we recalculated the phenotype frequencies for the HLA-B*51-negative subjects to exclude the effects of the linkage disequilibrium with the HLA-B*51 allele, HLA-A*2601 was most strongly associated with BD. In addition, we observed a significant association between several clinical features and some alleles, including HLA-A*2602., Conclusion: The significant increase of HLA-A* 26 in the BD patients without HLA-B*51 suggests that this allele itself might be one of the primary susceptibility genes involved in the development of BD independently of HLA-B*51.

Predisposition to alcohol dependence is affected by multiple environmental and genetic factors in complicated way. Family and twin studies estimated about 60% of hereditary rate for alcoholism. Many lines of evidence by divergent methods, e.g. gene-manipulated animals, linkage of human genome and genetic association studies, are accumulating for molecular genetic components involved in alcoholism. These studies have shown that genetic polymorphisms of the genes encoding alcohol metabolism enzymes and neurotransmitter signaling molecules in dopamine, GABA, opioid and serotonin systems, were substantially involved in individual variation of susceptibility to alcohol dependence. Recent whole-genome association examination using 500K gene-chip revealed that a set of genes of adhesion and cytoarchitecture molecules were also involved in the disorder. These unexpected new findings by gene-chip technology, which need to be confirmed by case-control association one by one, must bring about breakthrough in investigation of neural mechanisms of alcohol dependence and innovative therapy.

A 55-year-old man, who had not suffered from any severe or recurrent bacterial infections previously, visited our hospital because of symptoms of fever, cough, sputum, and otorrhea. Chest X-ray and computed tomography demonstrated infiltrates in the right middle lobe and lingula. Pneumococcal pneumonia and tympanitis were diagnosed based on the isolation of Streptococcus pneumoniae from sputum and otorrhea specimens. A peripheral blood analysis showed a remarkable reduction in serum IgG level and the flow cytometric analysis of his peripheral monocytes indicated a significant reduction in Bruton's tyrosine kinase expression. Thus, we diagnosed his illness as X-linked agammaglobulinemia (XLA). Although immunoglobulin replacement therapy was performed, he developed recurrent lower respiratory tract infections. Low-dose long-term erythromycin treatment resulted in decreased frequency of respiratory tract infections. These results suggest that erythromycin therapy may be useful for the control of lower respiratory tract infections in patients with XLA. Even in adults with recurrent bacterial respiratory tract infections, the presence of XLA as an underlying disease should be considered. The effect of macrolide therapy for chronic lower respiratory tract infection associated with humoral immunodeficiency has rarely been reported. This case study may provide valuable information about macrolide therapy for such an infection in patients with humoral immunodeficiency.

Recent clinical research have revealed that more than 70% of the patients with ALS/PDC, which is highly prevalent in Hohara area in the Kii peninsula, have family history. 80% of Guamanian patients, who have identical pathological findings to those of ALS/PDC in Kii, are also known to have family history with non-Mendelian trait. These facts suggest strong genetic predisposition to ALS/PDC in both Kii and Guam. However, no genes associated with ALS/PDC have been identified by molecular genetic studies using candidate gene approach. To identify the causative or susceptibility genes for ALS/PDC, we have conducted a genomewide linkage analysis for five families with ALS/PDC in Hohara. The fact that affected individuals were ascertained in successive generations suggest an autosomal dominant (AD) inheritance, while the presence of consanguinity suggests an autosomal recessive (AR) inheritance. Although we can raise possibilities of AD model with incomplete penetrance or AR model with high gene frequency (pseudo-dominant model), the mode of inheritance of ALS/PDC families is complicated and controversial. Therefore, we are also conducting model-free (non-parametric) linkage analysis to identify the disease locus without setting mode of inheritance. More family members and detailed clinical evaluations are required to obtain the convincing evidence of linkage.

We report the clinical course of a case of X-linked lissencephaly with absent corpus callosum and abnormal genitalia (XLAG) exhibiting severe diarrhea. The patient demonstrated lactose intolerance and his intractable seizures were relieved with lactose-free, extensively hydrolyzed whey protein formula. At the age of 2 years while being treated with the antiallergic formula, he was affected with severe diarrhea that resembled watery diarrhea-hypokalemia-acidosis syndrome (WDHA). Administration of octreotide was effective in relieving his secretory diarrhea. Hypoglycemia without hyperinsulinemia was seen during fasting, and plasma vasoactive intestinal polypeptide was not increased when he had WDHA-like diarrhea. Although pancreas of ARX mutant mice revealed an increased number of beta and delta cells, we did not detect the cause of hypoglycemia and secretory diarrhea by pancreatic endocrinology. His urinary findings mimicked the symptoms of Fanconi syndrome, so it was possible that his hyperaldsteronemia affected not only his intestinal tract, but also his renal tubules.

Parkinson's disease (PD) is the second most common neurodegenerative disorder in the world. The occurrence of PD is largely sporadic, while several families with Mendelian segregation of PD have been reported. PD is thought to be caused by mitochondrial dysfunction, oxidative stress and inflammation based on multiple genetic and environmental factors, resulting in the apoptosis of dopaminergic cells. Six causal genes for Mendelian inherited PD have been identified to date, which indicate the importance of the ubiquitin-proteasome pathway in the molecular pathogenesis of dopaminergic cell death. Recent studies have also indicated the involvement of genetic factors in the pathogenesis of sporadic PD. Many association studies on candidate genes have examined the relationship between PD and polymorphisms; We identified a-synuclein as a definite susceptibility gene for sporadic PD. Since 2001, significant linkage to several loci have been reported in samples of affected sibling pairs. With the recent advances in human genome analyses, genome-wide association studies by SNP chip are being performed to identify susceptibility genes and to establish tailor-made medicine for PD.

Inherited neuropathies are clinically and genetically heterogeneous. At least 28 genes and 12 loci have been associated with Charcot-Marie-Tooth disease (CMT) and related inherited neuropathies. Most causes of inherited neuropathy have been discovered by positional cloning technique and in the past two years, the pace of CMT gene discovery has accelerated. Genetic studies have revealed the following gene mutations as the causes of inherited neuropathies; PMP22, MPZ, EGR2, SOX10, SIMPLE/LITAF, ARHGEF10 for CMT1 (autosomal dominant demyelinating form); GDAP1, MTMR2, SBF2/MTMR13, KIAA1985, NDRG1 PRX for CMT4 (autosomal recessive demyelinating form), MFN2, KIF1B, RAB7, GARS, NEFL, HSPB1, HSPB8 for CMT2 (autosomal dominant axonal form); LMNA, GAN1, KCC3, TDP1, APTX, SETX for AR-CMT2 (autosomal recessive axonal form); GIB1 for CMTX (X-linked CMT); DNM2 for CMT-DI (autosomal dominant CMT with intermediate nerve conduction velocities); and DHH for minifascicular neuropathy. These discovered CMT causing genes/proteins include those which show unpredictable correlations with the peripheral nervous system. However, these genes/proteins are definitely important for the peripheral nerve, and their discovery should pave the way for dramatic progress in the understanding of peripheral nerve biology. On the other hand, genotype-phenotype correlations of these genes are also important in order to understand the pathomechanisms of inherited neuropathy. Because, based on mutation studies, a large number of genes associated with both the CMT1/4 and CMT2 forms have been identified, it is usually difficult to predict the causative gene based on clinical information from patients without specific complications. To clarify the specific features and molecular mechanisms of five diseases that we previously reported, we reviewed recent progress in HMSN-P linked to chromosome 3, CMT4F caused by PRX, CMT4A caused by GDAP1, CMT4B2 caused by SBF2/MTMR13, and SCAN1 caused by TDP1. HMSN-P is characterized by late onset, proximal dominant severe muscle weakness, fasciculations, muscle cramp and sensory involvement. HMSN-P is a primary neuronopathy. Mutations in periaxin are associated with a broad spectrum of demyelinating neuropathies including DSS, a sensory dominant form and early onset slowly progressive CMT. Pathologically, loss of myelinated fibers, demyelination, small onion bulb formations, tomacula formation and myelin foldings were seen in sural nerves. Absence of septate like junction in the paranodal loop suggests that periaxin could be required for the adhesion complex. GDAP1 is a relatively common cause of CMT4. Half of reported patients showed the demyelinating form, while the rest showed the axonal form. The typical feature of CMT4A is paresis of the vocal cords and diaphragm. CMT4B2 is characterized by autosomal recessive, juvenile onset glaucoma and focally folded myelin in sural nerves. SBF2/MTMR13 mutations cause CMT4B2. Early onset glaucoma was seen in patients with nonsense mutations. SBF2/MTMR13 and MTMR2, which is the cause of CMT4B1, could be acting on the same 3-phosphoinositide signaling pathway. Clinical phenotypes of patients with TDP1, APTX, or SETX mutations share common clinical findings, namely cerebellar ataxia and axonal neuropathy. TDP1 and aprataxin both act on the single strand break repair pathway, with TDP1 working specifically on topoisomerase I related SSBR. Senataxin is a RNA helicase acting on RNA maturation and termination in yeast. Since these three proteins share a common pathway, disruption in any of them could induce a delay in the transcription process. The low rate of protein supply could lead to deaths of large neuronal cells.

The metabolic syndrome(MS) is a multifactorial complex trait that is influenced by both environmental and genetic factors. Factor analyses of several large population-based studies have shown that MS is genetically composed of at least 3-4 independent components. Mutations and polymorphisms in the genes associated with insulin resistance, adipocyte abnormality, chronic inflammation, or autonomic imbalance may underlie the etiological basis of MS. Above all, genes for several transcription factors such as PPARs and SREBPs and adipocytokines such as leptin and adiponectin are promising candidates. Genome-wide linkage analyses with affected sib-pairs have identified several chromosomal regions where major susceptible genes to MS may exist and have indicated that the underlying genes would differ among the races.

Schizophrenia is a relatively common but genetically complex disorder, making the identification of susceptibility genes formidable. However, progress in genetic studies on schizophrenia during the past ten years has revealed several replicated linkage loci, which span over multiple chromosomal regions. Since last year, several causal genes have been isolated from those linkage regions. All of these have proven to have some functional relevance to glutamatergic neurotransmission. These results are interesting because the "hypoglutamatergic hypothesis" for pathophysiology of schizophrenia has been articulated since the early eighties. This hypothesis has been supported both by pharmacological evidence that administration of NMDA-type glutamate receptor antagonists induces schizophrenia-like symptoms and by neurophysiological studies. Recent lines of evidence from a candidate gene approach have also endorsed the hypothesis. Here, we introduce the overview of recent progress in genetic studies that converge to depict the hypothesis of glutamatergic hypofunction in schizophrenia.

We are aiming to identify susceptibility genes for common or otherwise clinically relevant diseases of metabolism such as diabetes, asthma, and hypertension, and analyze the molecular causality. Although genetic and environmental factors play equally crucial roles in the pathogenesis of the common diseases of civilization, genetic factor is directly involved in the causality and molecular mechanism. The elucidation of molecular etiology provides specific molecular targets for therapeutic drugs even at the individual level. Thus our priority is analysis of the molecular causality of the common metabolic disorders of civilization. We will identify individual and group polymorphisms (SNPs) in the genome relevant to the treatment of individual patients closely related to susceptibility to disease, prognosis of disease, and responses to drugs. To determine the genetic susceptibilities, we apply genetic approaches such as linkage studies with affected sib-pairs and association studies using SNPs database together with haplotype analysis.

There are 2 different approaches to search for disease-related genes: a knowledge-based approach using the functions of molecules, and a statistics-based approach using polymorphisms. In the latter approach, researchers search for disease-related sequences or test the association between the sequence and the disease using statistics. Statistical methods are classified into 2 subdivisions: a linkage-based method and a linkage-disequilibrium-based method. For the former method, Mendel's laws are directly applied and the samples should be families, while for the latter method, Mendel's laws are only indirectly applied and the samples do not have to be families. As an example of the former method, an algorithm of linkage analysis based on the Lander-Green algorithm in which hidden Markov model is used is explained herein. As an example of the latter method, a program inferring haplotype frequencies and diplotype configurations of individuals is explained.

Mood disorders are common diseases and cause a big burden on society, including suicide. Because there are many treatment resistant cases in mood disorders, it is very important to elucidate the pathophysiology of this condition to establish its prevention and its treatment. Genetic epidemiological studies have shown that genetic factors have an important role in the pathophysiology of mood disorders; therefore the molecular genetics studies of this condition have been extensively performed, such as positional approach (i.e., linkage study) and candidate gene approach (i.e., association study). Linkage studies have shown some candidate locations that have been reproduced in two or more studies, such as 1q21-42, 4p16, 10q21-26, 11p15, 12q23-24, 13q11-32, 18p11, 18q21-22, 22q11-13, Xp11, and Xq24-28. Most association studies have until now focused on the neurotransmitter system as a candidate molecule including serotonin transporter, serotonin receptors, dopamine receptors, tyrosine hydroxylase, MAO-A, COMT, and tryptophan hydroxylase. Moreover, phamacogenetic studies also have been carried out in this field to develop new drugs as well as personalized medicine. Future molecular genetic studies will find out the mood-disorder susceptible genes and open the gate to true treatment and prevention of this disorder as the Human Genome Project attains its goal.

Frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) is a familial neurological disorder, characterized genetically by autosomal dominant inheritance, clinically by behavioral abnormalities and parkinsonism, and neuropathologically by tauopathy. Linkage analyses of affected families have led to identification of many exonic and intronic mutations in the tau gene. Using site-specific antibodies that distinguish between wild-type and mutant tau, we analyzed molecular species of tau in the soluble and insoluble fractions of the brain affected by two FTDP-17 mutations, P301L and R406W. Western blotting showed that mutant tau was preferentially deposited in the Sarkosyl-insoluble fraction of the P301L brain. Consistent with this, immunocytochemistry showed that intraneuronal tau deposits consisted exclusively of mutant tau. On the other hand, the protein levels of mutant tau in the soluble fraction were selectively decreased despite no detectable decrease in its mRNA levels. In contrast, almost equal amounts of wild-type and mutant tau were present in the Sarkosyl-insoluble fraction of the R406W brain and their levels in the soluble fraction did not differ from each other. Wild-type and mutant tau colocalized in neurofibrillary tangles in the frontotemporal cortices. In contrast to soluble R406W tau, which was less phosphorylated than soluble wild-type tau. Sarkosyl-insoluble R406W tau was highly phosphorylated to a similar extent as insoluble wild-type tau.

We report the anesthetic management of a 4-yr-old boy with Simpson-Golabi-Behmel syndrome. This syndrome is an X-linked condition characterized by pre- and postnatal overgrowth with visceral and skeletal anomalies. Affected males have a distinctive facial appearance with wide nasal bridge, anteverted nostrils, wide-open mouth, enlarged tongue, and large protruding maxilla and jaw. Although it had been speculated preoperatively that airway management would be complicated by the macroglossia, there was no difficulty in endotracheal intubation in the present patient. Preparations for difficult airway management should be made by the anesthesiologist before induction of anesthesia.

A series of studies have indicated the existence of genetic predisposition and the polygenic-multifactorial mode of transmission for bipolar disorder(BPD). Linkage studies have defined several BPD susceptibility loci. The findings to date suggested the candidate regions on 4p16, 12q23-24, 18p11, 18q22, 21q22, Xq24-27 for BPD, although no genes has yet been definitively identified. There are also many reports on the analyses of candidate genes, using association studies. But none of gene polymorphisms have been established as firm disease alleles with sufficient replications. Novel statistical methods and development of new strategies are necessary to approach the goal of isolating susceptibility genes.

Recent genetic studies using nonparametric linkage analyses have suggested that several chromosomal regions linked with hypertension. On the other hand, statistical estimation implied that linkage analyses did not have enough power to identify hypertension-susceptible genes that seemed to have weaker effects on blood pressure than expected previously. Although association analyses using single-nucleotide polymorphisms have been introduced with enthusiasm, it is necessary to solve several questions before we can apply this strategy to identify hypertension-susceptible genes. Not genotyping but phenotyping will become more and more important in the genetic studies of hypertension.