Hereditary breast carcinomas associated with BRCA1/2 mutations have unique clinicopathological and epidemiological characteristics. The objective of this study is to outline the prevalence, founder effect and clinicopathological characteristics of BRCA1/2 mutations for hereditary breast cancers from an analysis of reports recently published regarding Korean subjects. The prevalence of BRCA1 and/or BRCA2 mutations is 2.5-3.1% for sporadic breast cancers, 19.4-42.9% for familiar breast cancer patients with two or more affected first- and second- degree relatives with breast or ovarian cancers and 9.6-18.3% for early breast cancers. Common mutations for the Korean subjects were 2552delC, 3476insA, 4184del4, 5589del8, and 5615del111insA for BRCA1; and 7708C>T for BRCA2. These mutations were not found in Ashkenazi Jewish or Icelandic subjects. The proportion of estrogen or progesterone receptor (ER/PR) or ER/PR/HER2 triple negative status, basal-like phenotype as detected by immunohistochemical staining, and undifferentiated histological grade in Korean BRCA mutation subjects were higher than in subjects lacking BRCA1/2 mutations. Our review found that previous studies describing BRCA mutations among Korean subjects were limited. Since the clinicopathological, phenotypic and epidemiological characteristics of the BRCA1/2 mutations among Korean subjects are different from those among subjects from the Americas and Europe, more studies of hereditary or familial breast cancer including BRCA mutations must be conducted. A largescale prospective study called Korean Hereditary Breast Cancer Study (KOHBRA) was started from May 2007, and future information provided by the KOHBRA study will make a substantial contribution to solving the basic questions in etiology, individual susceptibility and clinicopathological characteristics for hereditary breast cancer among Korean subjects.
Americas ; Breast ; Breast Neoplasms ; Estrogens ; Europe ; Founder Effect ; Humans ; Iceland ; Ovarian Neoplasms ; Phenotype ; Prevalence ; Receptors, Progesterone

BACKGROUND/AIMS: Wilson's disease (WD) is an inherited disorder of copper metabolism caused by alteration of the P-type adenosine triphosphatase (ATP) 7B gene. In this study, we analyzed the frequency of well-known mutations and constructed the first haplotypes for Koreans. In addition, we evaluated whether a founder effect existed in Korean patients with WD. METHODS: We obtained DNA samples from 21 patients with WD and their parents (total cohort n=63). ATP7B gene mutations were identified by direct sequencing methods, and microsatellite typing was performed at D13S315, D13S1325, and D13S316 with fluorescent dye-labeled primers. Any founder effect was identified by using 42 normal alleles from parents with a normal phenotype as a control group. The chi-square test and Fisher's exact test were used for statistical analysis. RESULTS: Three common mutations were found in 23 chromosomes obtained from 21 patients: the R778L mutation at exon 8 (15/23, 65.2%), the A874V mutation at exon 11 (6/23, 26.1%), and the N1270S mutation at exon 18 (2/23, 8.7%). D13S315 and D13S316 showed linkage disequilibrium at alleles 5 and 4, respectively, in patients with the R778L mutation (P=0.0157 and 0.0001, respectively). The haplotype made up of these two alleles occurred significantly more frequently in patients with the R778L mutation (5-R778L-4, D13S315-mutation-D13S316) than in the controls (P=0.0018). CONCLUSIONS: The arche haplotype of the ATP7B gene in Korean patients with WD may be 5-R778L-4 (D13S315.mutation.D13S316), and it might illustrate a founder effect.
Adenosine Triphosphatases/*genetics ; Amino Acid Substitution ; Cation Transport Proteins/*genetics ; *Founder Effect ; Gene Frequency ; Genotype ; Haplotypes ; Hepatolenticular Degeneration/diagnosis/*genetics ; Humans ; Microsatellite Repeats ; *Mutation ; Republic of Korea

OBJECTIVES: Hearing impairment (HI) is the most common sensory deficit in human. The Gap Junction Protein, Beta-2 (GJB2) gene encodes the protein connexin 26, and this gene accounts for up to half of the cases of autosomal recessive nonsyndromic HI. This study was conducted to obtain a set of sequence variations (SVs) of the GJB2 gene among Koreans from the general population for making molecular genetic diagnoses and performing genetic counseling. METHODS: We resequenced the GJB2 gene in 192 chromosomes from 96 adult individuals of Korean descent and who were without a history of hearing difficulty. The data of the SVs was obtained and the haplotypes were reconstructed from the data. RESULTS: Five SVs were observed, including a novel one (c.558G>A; p.T186T), with the allele frequencies ranging from 0.5% (1/192) to 41% (79/192). The linkage disequilibrium study and haplotype construction showed that some of the SVs are in tight linkage, resulting in a limited number of haplotypes. CONCLUSION: We observed SVs of the GJB2 gene with different allele frequencies, and a limited number of haplotypes were constructed. The data from this study can be used as reference data for GJB2-related hearing genetic studies, including studies on the founder effect and population genetics, and this data is particularly relevant to people of East Asian decent.
Adult ; Asian Continental Ancestry Group ; Connexins ; Founder Effect ; Gene Frequency ; Genetic Counseling ; Genetics, Population ; Haplotypes ; Hearing ; Hearing Loss ; Humans ; Korea ; Linkage Disequilibrium ; Molecular Biology

BACKGROUND: Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare inherited disorder characterized by infantile-onset macrocephaly, slow neurologic deterioration, and seizures. Mutations in the causative gene, MLC1, are found in approximately 75% of patients and are inherited in an autosomal recessive manner. We analyzed MLC1 mutations in five unrelated Korean patients with MLC. METHODS: Direct Sanger sequencing was used to identify MLC1 mutations. A founder effect of the p.Ala275Asp variant was demonstrated by haplotype analysis using single-nucleotide polymorphic (SNP) markers. Multiple ligation-dependent probe amplification (MLPA) and comparative genomic hybridization plus SNP array were used to detect exonic deletions or uniparental disomy (UPD). RESULTS: The most prevalent pathogenic variant was c.824C>A (p.Ala275Asp) found in 7/10 (70%) alleles. Two pathogenic frameshift variants were found: c.135delC (p.Cys46Alafs*12) and c.337_353delinsG (p.Ile113Glyfs*4). Haplotype analysis suggested that the Korean patients with MLC harbored a founder mutation in p.Ala275Asp. The p.(Ile113Glyfs*4) was identified in a homozygous state, and a family study revealed that only the mother was heterozygous for this variant. Further analysis of MLPA and SNP arrays for this patient demonstrated loss of heterozygosity of chromosome 22 without any deletion, indicating UPD. The maternal origin of both chromosomes 22 was demonstrated by haplotype analysis. CONCLUSIONS: This study is the first to describe the mutational spectrum of Korean patients with MLC, demonstrating a founder effect of the p.Ala275Asp variant. This study also broadens our understanding of the mutational spectrum of MLC1 by demonstrating a homozygous p.(Ile113Glyfs*4) variant resulting from UPD of chromosome 22.
Alleles ; Chromosomes, Human, Pair 22* ; Comparative Genomic Hybridization ; Exons ; Founder Effect ; Haplotypes ; Humans ; Leukoencephalopathies* ; Loss of Heterozygosity ; Megalencephaly ; Mothers ; Seizures ; Uniparental Disomy*

Asian Continental Ancestry Group ; genetics ; Carnitine Acyltransferases ; deficiency ; genetics ; China ; Founder Effect ; Humans ; Infant, Newborn ; Male ; Mutation ; Sudden Infant Death ; genetics

Phenylketonuria is metabolic disorder that results from a deficiency of the hepatic phenylalanine hydroxylase. But among patients with hyperphenylalaninemia, the defect resides in one of the enzymes necessary for production or recycling of tetrahydrobiopterin (BH4). The reduction of BH4 affects not only phenylalanine metabolism but also formation of the tyrosine related neurotransmitter, dopamin and tryptophan related neurotransmitter, serotonin. Administration of L-dopa and 5-hydroxytriptophan seems to be the most effective treatment and may prevent irreversible neurologic damage if started early in life in hyperphenylalaninemia due to deficiency of cofactor BH4. Therefore, all patients with PKU and hyperphenylalaninemia should be tested for BH4 deficiency as early as passible. So we measured reduced forms of biopterin in urines of 19 phenylketonuria patients by Funkushima and Nixon method and 13 of PKU patients measured dihydropterin reductase (DHPR) in white blood cells by modified Narisawa method. We could not find abnormal pterin patterns of cofactor BH4 and normal value of DHPR. All Korean 19 PKU children were classic PKU. A missense mutation has been identified in the phenylalanine hydroxylase (PAH) gene of 16 Koran PKU patients. 5 mutations (IVS4, Y204 C, R243Q, Y356 X, R413 P) have been identified. The frequency of these mutations was found to be 50% of PKU alleles. The IVS4 mutation had a high frequency in Korea and southern China, due to the result of the founder effect and genetic drift. the R413 P mutation, which may have originated in the regions surrounding the Baikal, expanded to northen China and Japan. We were not able to find Caucasian mutations in Korean ptiets. PKU mutations occured after racial divergence between Caucasian and Mongoloids. We observed that PKU patients with Y 204 C and R413 P mutations showed mild mild clinical phenotype but IVS4 mutation had severe mental retardation. the establishment of genotype will therefore aid in the prediction of clinical phenotypes in patients with this disease. So, pterin and DHPR measurement and DNA analsis will be useful for prognosis and proper treatment of PKU patients.
Alleles ; Biopterin ; Child ; China ; DNA* ; Founder Effect ; Genetic Drift ; Genotype ; Humans ; Intellectual Disability ; Japan ; Korea ; Leukocytes ; Levodopa ; Metabolism ; Mutation, Missense ; Neurotransmitter Agents ; Oxidoreductases ; Phenotype ; Phenylalanine ; Phenylalanine Hydroxylase ; Phenylketonurias ; Prognosis ; Recycling ; Reference Values ; Serotonin ; Tryptophan ; Tyrosine

AIMTo identify the genotype of two Indians with male pseudohermaphroditism.

METHODSStandard radioimmunoassay procedure was used for estimating hormonal levels. Conventional cytogenetic analysis was carried out for diagnosing the genetic sex in these subjects with genital ambiguity. Molecular analysis was carried out by standard polymerase chain reaction procedure using different sets of primers and reaction conditions specific for the 5alpha-reductase type 2 gene (SRD5A2) gene. Direct sequencing was carried out using the ABI Prism dye terminator sequencing kit and the ABI 310 sequencing apparatus.

RESULTSWe found an SRD5A2 gene mutation in exon 5, where arginine is substituted with glutamine (R246Q), in two males with pseudohermaphroditism and ambiguous genitalia from unrelated families. This is the first time this mutation has been reported in individuals from India.

CONCLUSIONIdentification of the R246Q mutation of the SRD5A2 gene from two unrelated Indian families possibly extends the founder gene effect.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase ; genetics ; Child ; Dihydrotestosterone ; blood ; Disorders of Sex Development ; genetics ; pathology ; Family Health ; Follicle Stimulating Hormone ; blood ; Founder Effect ; Genitalia, Male ; abnormalities ; Humans ; Hypospadias ; genetics ; pathology ; India ; Luteinizing Hormone ; blood ; Male ; Mutation, Missense ; Testosterone ; blood

OBJECTIVETo investigate the transforming growth factor beta induced (TGFBI; BIGH3) gene mutation and founder effect of two large Chinese families clinically diagnosed as Thiel-Behnke corneal dystrophy.

METHODSFifteen members including 13 affected and 2 healthy in family A, 14 members including 6 affected and 8 healthy in family B, as well as 20 other unrelated healthy individuals were tested for TGFBI gene mutation. Haplotype analysis and clinical examination were also carried out in the two families.

RESULTSIn exon 12 of the TGFBI gene, 1664G to A change was detected in all the patients, which leads to an amino acid replacement of arginine with glutamine (p.Arg555Gln). Members of the two families share some similar haplotypes.

CONCLUSIONGenetic analysis is helpful in the diagnosis of corneal dystrophy. The two families may come from a same ancestor.

Adolescent ; Adult ; Aged ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; Child ; Corneal Dystrophies, Hereditary ; diagnosis ; genetics ; Exons ; Extracellular Matrix Proteins ; genetics ; Female ; Founder Effect ; Humans ; Male ; Middle Aged ; Molecular Sequence Data ; Pedigree ; Point Mutation ; Transforming Growth Factor beta ; genetics ; Young Adult