Tsunenori Hirayama

Eight novel mutations and functional impairments of the LDL receptor in familial hypercholesterolemia in the north of Japan

AbstractIn the course of investigations of familial coronary artery disease in Hokkaido, the northland of Japan, we identified 13 families affected by familial hypercholesterolemia. Among them, we identified eight novel mutations of the low-density lipoprotein (LDL) receptor gene, four of which caused frameshifts: (1) a 7-bp deletion at nucleotide (nt) 578–584 (codon 172–174, exon 4); (2) a 14-bp insertion at 682 nt (codon 207–208, exon 4); (3) a 49-bp deletion at nt 943–991 (codon 294–310, exon 7); and (4) a one-base insertion of C to a stretch of C3 at nucleotides 1687–1689 or codon 542. The others included (5) a T-to-C transition at nt 1072 causing substitution of Cys for Arg at codon 337 (C337R, exon 8); (6) a splice-site G-to-T substitution in intron 11; (7) a splice-site G-to-C substitution in intron 11; and (8) a G-to-T transition at nt 1731 causing substitution of Trp for Cys at codon 556 (W556C, exon 12). To disclose the functional consequences of novel mutations, we characterized each of these mutations by two assays in peripheral lymphocytes, i.e., uptake of fluorescently labeled LDL by LDL receptors, and measurement of cell surface-bound LDL receptor protein using specific monoclonal antibody against LDL receptor.

Five familial hypercholesterolemic kindreds in Japan with novel mutations of the LDL receptor gene

AbstractIn the course of investigations of familial coronary artery disease in Hokkaido, the northern island of Japan, we identified five families in which multiple members showed elevated plasma levels of low-density lipoprotein (LDL) cholesterol. To determine the genetic etiology of their lipoprotein abnormalities, we screened DNA samples from these families for mutations in all 18 exons and the exon-intron boundaries of the LDL receptor (LDLR) gene. Novel point mutations were identified in each family: (1) a C-to-A transversion at nucleotide 285, causing a nonsense mutation at codon 74, in eight members of family A; (2) a G-to-A transition at nucleotide 1136, causing substitution of Tyr for Cys at codon 358, in six members of family B; (3) a C-to-T transition at nucleotide 1822, causing substitution of Ser for Pro at codon 587, in five members of family C; (4) a one-base insertion of G to a five-G stretch at nucleotides 1774–1778 (codons 571–572), causing a frameshift, in six members of family D; and (5) a one-base deletion of T at nucleotide 1963–1964 (codon 634), causing a frameshift, in three members of family E. Through the molecular genetic approach a total of 28 individuals in these families were diagnosed unequivocally as heterozygous for the respective LDLR mutations. This method also helped us to diagnose familial hypercholesterolemia, or to exclude from carrier status, 11 children with borderline high cholesterol levels.

A novel LDLR mutation, H190Y, in a Utah kindred with familial Hypercholesterolemia

AbstractHeterozygous familial hypercholesterolemia (FH) is a serious disorder causing twice normal low-density lipoprotein (LDL) cholesterol levels early in childhood and very early coronary disease in both men and women. Treatment with multiple medications together with diet can normalize cholesterol levels in many persons with FH and prevent or delay the development of coronary atherosclerosis. Previously published blood cholesterol criteria greatly under-diagnosed new cases of FH among members of known families with FH and over-diagnosed FH among participants of general population screening. Thus, there is a need for accurate and genetically validated criteria for the early diagnosis of heterozygous FH. In the course of investigations of coronary artery disease in Utah, we identified a family whose proband showed elevated plasma levels of LDL cholesterol. To carry out molecular genetic diagnosis of the disease, we screened DNA samples for mutations in all 18 exons and the exon-intron boundaries of the LDL receptor gene (LDLR). Novel point mutations were identified in the proband: a C-to-T transversion at nucleotide position 631, causing substitution of tyrosine for histidine at codon 190 in exon 4 of the LDLR gene. The mutant allele-specific amplification method was used to examine 12 members of the family recruited for the diagnosis. This method helped to unequivocally diagnose 7 individuals as heterozygous for this particular LDLR mutation, while excluding the remaining 5 individuals from carrier status with FH.

Novel mutations of the LDL Receptor Gene in Familial Hypercholesterolemia Pedigrees in Hokkaido

In the course of investigations of familial coronary artery disease in Hokkaido, the northern island of Japan, we identified five families in which multiple members showed elevated plasma levels of LDL cholesterol. To determine the genetic etiology of their lipoprotein abnormalities, we screened DNA samples from these families for mutations in all 18 exons and the exon- intron boundaries of the low-density lipoprotein receptor (LDLR) gene. Novel point mutations were identified in each family: (1) a C-to-A transversion at nucleotide 285, causing a nonsense mutation at codon 74, in eight members of family A; (2) a G-to-A transition at nucleotide 1136, causing substitution of Tyr for Cys at codon 358, in six members of family B; (3) a C-to-T transition at nucleotide 1822, causing substitution of Ser for Pro at codon 587, in five members of family C; (4) a one-base insertion of G to a five-G stretch at 1774-8 (codons 571-572), causing a frameshift, in six members of family D; (5) a one-base deletion of T at nucleotide 1963-4 (codon 634), causing a frameshift, in three members of family E. Through the molecular genetic approach a total of 28 individuals were diagnosed unequivocally as heterozygous for the respective LDLR mutations in these families. This method also helped us to diagnose with FH, or to exclude from carrier status, eleven children with borderline high cholesterol levels.

A non-functional pituitary adenoma in a 13-year-old boy of short stature

of the right frontal, temporal, and parietal lobes. He develdifference between our patient and reported patients with oped a GTC 1 month after this MRI procedure. typical hemimegalencephaly. Conclusion: Neuronal migration disorders can be recognized distinctly on MRI. MRI revealed that the ectopic gray matter exhibits a wide spectrum, from the double cortex syndrome (case 3) to a nodular heterotopia (case 1). The accumulation of patient records will help to clarify the clinical status more precisely.