[Iodide transport defect (abnormalities in the Na+/I(-) symporter gene)].
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Congenital Hypothyroidism↗
Biomedical subjects
Shinji Kosugi
Publications and source records attributed to Shinji Kosugi.
Extending the clinical heterogeneity of iodide transport defect (ITD): a novel mutation R124H of the sodium/iodide symporter gene and review of genotype-phenotype correlations in ITD.
CONTEXT: Iodide transport defect (ITD) is an autosomal recessive disorder resulting in varying degrees of congenital hypothyroidism (CH) with goiter and low or absent radioiodide uptake (RIUT), as determined by thyroid scintigraphy, and low iodide saliva to plasma ratio. Defects of the sodium/iodide symporter gene (NIS) have been shown to cause ITD. OBJECTIVE: We describe molecular studies of NIS in a patient with ITD and genotype-phenotype correlation analysis in 31 patients with NIS defects reported worldwide. DESIGN: NIS sequencing and functional studies of the new NIS mutation in vitro were performed. RESULTS: In a newborn with symptomatic CH and a large goiter, thyroid scintigraphy showed no RIUT (0%). NIS sequencing identified the new homozygous mutation, R124H, in exon 2. This mutation was associated with abolition of iodide uptake in vitro when transfected in COS-7 cells. Immunocytochemical studies documented correct targeting of the mutated protein to the plasma membrane of transfected cells. Genotype-phenotype correlation analysis showed that the onset of hypothyroidism occurred during the neonatal period with four NIS mutations (neonatal onset of hypothyroidism genotype), during infancy with three NIS mutations (infancy onset of hypothyroidism genotype), and during childhood with three NIS mutations (childhood onset of hypothyroidism genotype). RIUT is a direct measure of residual NIS activity in vivo. Mean RIUT was lower in patients with the neonatal onset of hypothyroidism genotype (0.88 +/- 0.2%) than in the infancy onset of hypothyroidism (1.9 +/- 0.4%; P < 0.05) and childhood onset of hypothyroidism (2.6 +/- 0.7%; P < 0.05) genotypes. CONCLUSIONS: We identified a new NIS mutation, R124H, in a newborn with the complete clinical ITD phenotype. Genotype-phenotype correlations suggest that age at hypothyroidism onset may be genotype specific and may depend on genotype-specific residual NIS activity.
Age of Onset↗
A model of donors' decision-making in adult-to-adult living donor liver transplantation in Japan: having no choice.
This study examined the decision-making processes of donors in adult-to-adult living donor liver transplantation. Twenty-two donors were interviewed using a semi-structured format. Interview contents were transcribed verbatim and analyzed qualitatively using grounded theory. A decision-making model was developed consisting of 5 stages: (1) recognition, (2) digestion, (3) decision-making, (4) reinforcement, and (5) resolution. The second and the third stages described donors' experiences of "reaching a decision"; the fourth and fifth stages described those of "facing transplantation." The central theme of this model was "having no choice," which consisted of 4 codes: (1) priority of life, (2) only LDLT, (3) for family, and (4) only me. In conclusion, this model can help health care professionals to understand the donor experience and, based on that understanding, to provide sufficient support to the donor.
Adult↗
Detection of APC gene deletion by double competitive polymerase chain reaction in patients with familial adenomatous polyposis.
Familial adenomatous polyposis (FAP) is an autosomal dominant familial cancer syndrome caused by germline mutations of the tumor suppressor adenomatous polyposis coli (APC) gene. Heterozygous apc mutations have been identified in the majority of classical FAP patients who develop more than 100 colorectal adenomas. However, classical FAP patients often fail to display germline APC mutations detectable by routine mutation analysis. These apparently mutation-negative cases may be caused by heterozygous large genomic deletions. In the present study, FAP patients who showed no APC germline mutation detectable by the protein truncation assay and direct sequencing of protein coding exons were screened for APC gene deletion by a gene dose assay based on double competitive polymerase chain reaction. Gene dosage measurements within exon 15 of the APC gene identified two patients with gene deletion and one with possible gene duplication among 41 apparently mutation-negative patients. The deleted sequences in the two patients were determined by fine gene dose mapping around the APC gene and nucleotide sequencing of the deletion breakpoints. They were approximately 435-kilobase pair (kb) and 737-kb regions including the whole APC gene and flanked by a 4-base pair repeat and LINE-1 repetitive sequences, respectively. The chimeric LINE-1 element created at the breakpoint in the latter case also contained a short sequence derived from another LINE-1 element, suggesting a complex unequal homologous recombination event. These findings indicate that this gene dose assay is a useful technique to detect large gene deletions of the APC gene and to determine their genomic breakpoints.
Adenomatous Polyposis Coli↗
[Basic knowledge on genetic counseling that is necessary for internists].
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Female↗
Multiple endocrine neoplasia type 1 presenting as psychosis.
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Diagnosis, Differential↗
Multiple endocrine neoplasia type 1 gene mutations in sporadic gastrinomas in Japan.
The molecular mechanisms responsible for the development and/or progression of gastrinomas are largely unknown. Studies involving sporadic enteropancreatic neuro-endocrine tumors suggest that mutations in the MEN1 gene occur in some tumors and probably play an important role in their pathogenesis. In this study, we examined whether somatic mutations in the MEN1 gene are also responsible for sporadic gastrinomas and correlate with clinical manifestations of gastrinomas in Japanese patients. Genomic DNA was extracted from paraffin-embedded gastrinoma tissues from 12 patients. Nucleotide sequences in the MEN1 genes were determined by direct sequencing. We identified 6 mutations in 7 out of 12 examined gastrinomas (58%). The identified mutations were 1 non-sense, 2 missense, 1 deletion leading to frame shifts, 1 insertion and 1 splicing mutation. Identical mutations were found in three gastrinoma tissues. The age at surgery, the rate of hepatic metastasis, and tumor status were not significantly different in the 2 groups. This study demonstrates that alterations in the MEN1 gene are involved in about half of all sporadic gastrinomas, although no correlation between the presence of mutations and location and clinical phenotype or severity of disease has been found.
Adult↗
[Genetic, genomic and nucleic acid testing services provided by commercial laboratories].
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Clinical Laboratory Techniques↗
Germline mutations of the PTCH gene in Japanese patients with nevoid basal cell carcinoma syndrome.
We identified seven novel germline mutations of the PTCH gene in eight unrelated Japanese patients with nevoid basal cell carcinoma syndrome (NBCCS). In order to ensure genetic diagnosis, all 23 coding exons of the PTCH gene were amplified from genomic DNA by polymerase chain reaction (PCR) and sequenced. Mutations were found in all eight patients with NBCCS. The mutations detected in this study include one insertion/deletion mutation, one 1-bp insertion, two 1-bp deletions, one nonsense mutation and two missense mutations. None of the mutations have been previously reported. Five mutations caused premature stop codons that are predicted to result in a truncated protein. In the two missense mutations, the strong basic residue arginine was substituted by serine or glycine in highly conserved components of the putative transmembrane domain of PTCH, and these mutations may therefore affect the conformation and function of the PTCH protein. No phenotype-genotype relationships were found in the Japanese NBCCS patients, consistent with results of previous studies on NBCCS in African-American and Caucasian patients.
Adult↗
Multiple endocrine neoplasia type 1 in end-stage renal failure.
A 59-year-old woman with chronic renal failure due to type 2 diabetes mellitus (DM) is presented. Her father and a brother had a history of brain tumor. Her blood urea nitrogen and serum creatinine levels were 102 mg/dl and 4.5 mg/dl, respectively. Her serum Ca(2+) and Pi were within the normal range (9.4 mg/dl and 5.4 mg/dl, respectively). Her intact parathyroid hormone (PTH) level was 1 730 000 pg/ml. A (99m)Tc-methoxy-isobutylisonitrile scintigraphy showed high uptake in three parathyroid glands. A magnetic resonance image showed microadenoma in the pituitary gland. The serum gastrin level was high. Genetic examination revealed a mutation of the MEN1 gene (894-9 G --> A). From these findings, she was diagnosed with multiple endocrine neoplasia (MEN) type 1. Subsequently, a parathyroidectomy was performed successfully, a parathyroid gland was transplanted to her right forearm, and her serum Ca(2+) level was controlled at 8.5-9.0 mg/dl. It is very important to identify MEN1 if an end-stage renal disease (ESRD) patient has hyperparathyroidism with multigland involvement. Examination of the MEN1 gene may be valuable to make an accurate diagnosis and choose the appropriate therapy in some ESRD patients with hyperparathyroidism.
Adult↗
[From diagnosis to treatment: multiple endocrine neoplasia (MEN)].
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Humans↗
[Human germline genetic tests].
A guideline for genetic testing by 10 scientific societies was published recently. This can be summarized as follows. 1) Generalized medical care for genetic medicine is necessary when genetic testing is considered. 2) Analytical validity, clinical validity and clinical usefulness must be proven when genetic testing is applied to clinical medicine. 3) Informed consent must be given by the client before genetic testing is performed. 4) Information on an individual's genetic test must be protected tightly and should not be disclosed to others without permission from the client. 5) Genetic counseling must be performed before genetic testing is performed. 6) The purposes of genetic test performed to prepositus ((i) for definite diagnosis of the patient and (ii) for obtaining information by predictive tests for family members) should be clearly distinguished. 7) Genetic tests for detection of carrier status of specific genetic conditions should be carefully performed, because they do not affect the health condition themselves, but can be a cause of discrimination. 8) Predictive genetic tests must be performed very carefully, especially when no procedures of treatment/prevention are available. 9) In general, genetic testing of children should be considered when such tests provide clinical benefits to the children themselves.
Forecasting↗
A novel six-nucleotide insertion in exon 4 of the MEN1 gene, 878insCTGCAG, in three patients with familial insulinoma and primary hyperparathyroidism.
Three Japanese patients (a man and his two sons) in a family with clinical diagnosis of familial multiple endocrine neoplasia type 1 (MEN1) suffered from insulinoma(s), primary hyperparathyroidism and pituitary microadenoma. Genomic DNA of the patients was analyzed by sequencing for the MEN1 gene and an insertion of six nucleotides, CTGCAG, in exon 4, resulting in insertion of two amino acids, Leu-Gln, after the 256th amino acid of the menin (256insLQ), was identified. CTGCAG is a palindromic sequence and repeated twice in the wild-type allele (nucleotides 879-890). It is speculated that mutations involving only exon 4 of the MEN1 gene might induce development of insulinoma(s).
Adult↗
A novel peculiar mutation in the sodium/iodide symporter gene in spanish siblings with iodide transport defect.
Previously, we reported two Spanish siblings with congenital hypothyroidism due to total failure of iodide transport. These were the only cases reported to date who received long-term iodide treatment over 10 yr. We examined the sodium/iodide symporter (NIS) gene of these patients. A large deletion was observed by long and accurate PCR using primers derived from introns 2 and 7 of the NIS gene. PCR-direct sequencing revealed a deletion of 6192 bases spanning from exon 3 to intron 7 and an inverted insertion of a 431-base fragment spanning from exon 5 to intron 5 of the NIS gene. The patients were homozygous for the mutation, and their mother was heterozygous. In the mutant, deletion of exons 3-7 was suggested by analysis using programs to predict exon/intron organization, resulting in an in-frame 182-amino acid deletion from Met(142) in the fourth transmembrane domain to Gln(323) in the fourth exoplasmic loop. The mutant showed no iodide uptake activity when transfected into COS-7 cells, confirming that the mutation was the direct cause of the iodide transport defect in these patients. Further, the mutant NIS protein was synthesized, but not properly expressed, on the cell surface, but was mostly accumulated in the cytoplasm, suggesting impaired targeting to the plasma membrane.
Adult↗
[Non-autoimmune hyperthyroidism and hyperfunctioning thyroid adenomas caused by activating mutation of the thyrotropin receptor].
Constitutively activating mutations in the TSH receptor gene have been found in various disorders. Somatic mutations were identified in autonomously functioning thyroid nodules(AFTNs) and toxic multinodular goiters(TMNGs). Germline mutations were identified in autosomal dominantly inherited non-autoimmune hyperthyroidism and sporadic congenital hyperthyroidism. Most of activating TSH receptor mutations were identified in western countries. Only one Japanese family has been reported to have an activating TSH receptor mutation. Previous very poor and insensitive study identified no somatic TSH receptor activating mutations in 45 AFTNs and TMNGs developed in Japanese. Our recent study completely reversed their observation; about half of AFTNs in Japanese had activating mutations.
Adenoma↗
[Human gene tests as laboratory medicine in the post-genome era].
Massive and systematic information on human genes and genome is accumulating with progress in the Human Genome Project. Information on the genome has a characteristic digital signal that is appropriate for high-throughput handling by computers. Therefore, the field of gene tests has a high affinity to the field of laboratory medicine. In addition, it is a important survival strategy for departments of laboratory medicine to remain at the cutting edge. We must establish an infrastructure for utilizing genome information in clinical medicine and must anticipate numerous issues. The following issues need to be addressed. 1. Online database of human gene tests (http://www.kuhp.kyoto-u.ac.jp/idennet/DB/index2.html) 2. Anonymous handling of patients' samples 3. Establishment of independent Department of Clinical Genetics 4. Education of clinical geneticists 5. Quality control of human gene tests (especially germline mutation tests) 6. Education of technicians handling human gene tests.
Clinical Laboratory Information Systems↗
[How should be the genetic medicine in the near future?].
Massive and systematic information on human genes and genome is accumulating with progress in the Human Genome Project. Information on the genome has the characteristics of a digital signal appropriate for high-throughput handing by computers. Therefore, the field of gene tests has a high affinity to the field of laboratory medicine. In addition, it is important for survival strategy by departments of laboratory medicine that stand on the edge. We have to establish an infrastructure to utilize genome information in clinical medicine while anticipating numerous issues. The following issues need to be addressed in addition to the previous report(Rinsho Byori 50: 156-160, 2002) 1. Integral system for genetic medicine. 2. Center for human germline gene tests. 3. Quality control of human gene tests. 4. Epidemiological data of germline gene tests.
Clinical Laboratory Techniques↗