Category Archives: Gene Medicine

At a ceremony at Yale Center for Clinical Investigation on September 4, Yale School of Medicine and Yale New Haven Health System officially launched Generations, one of the largest DNA sequencing projects of its kind in the United States. The aim is to enroll more than 100,000 patients in and near Connecticut, whose DNA will then be analyzed by Yale scientists to develop useful data for predicting, preventing, and treating what may eventually be hundreds of gene-related conditions.

The process starts with a simple blood sample, with the patients identity hidden from the research teams to ensure personal privacy. As genetic trends related to specific diseases are found, Yale clinicians will put their findings into practice for patients of Yale Medicine and the Yale New Haven Health System. We learn from every patient whom we treat within the health center, said Brian R. Smith, MD, professor and chair of laboratory medicine, deputy dean for scientific affairs, co-director of the Yale Center for Clinical Investigation, and co-principal investigator of the Yale Clinical and Translational Science Award Program. As a consequence of that, we do a better job with the next patient we treat, and on and on.

In fact, patients receiving that improved treatment will include actual study volunteers, because Generations will provide those who give blood samples with the relevant personal genetic information that it finds. Theres a possibility that you will learn something about your own health and disease risks that could benefit you, said Michael F. Murray, MD, professor of genetics and director for clinical operations in Yales Center for Genomic Health. In just a couple of months, we give that information back to you and then guide you to get preventive care. Murray said that in about 3% of participants, risks of cancer or heart disease will turn up that they probably didnt know about. Once they know, they and their doctors can take steps to lower their risk or prevent disease. And that two to three percent will grow over time as we learn more about genetics.

It is a program exclusive to Yale. Nobody else has it. Nobody else will develop it and implement it the way we are, said Richard DAquila, president of Yale New Haven Hospital and Yale New Haven Health System, which is comprised of five hospitals, more than 150 ambulatory facilities, numerous physician practices, and other affiliated centers. It really defines what our hopes and aspirations are for an academically connected health system across the state of Connecticut and beyond.

Generations builds on a heritage of genetics-related firsts at Yale School of Medicine. Robert J. Alpern, MD, dean and Ensign Professor of Medicine noted that Yale actually had the foresight decades and decades ago to form the first department of genetics in the country. Now, with advances both in knowledge and in available technology, he said, we have the ability to tie it all together, and really participate in what is going to be a revolution in health care, and were really looking forward to being a part of it.

Potential participants can contact Generations at helpusdiscover@yale.edu or 1-877-978-8343.

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Yale Launches Comprehensive DNA ... - medicine.yale.edu

Mutations in the CACNA1C gene are responsible for all reported cases of Timothy syndrome. One mutation has been found in everyone diagnosed with classic, or type 1, Timothy syndrome. This mutation changes one protein building block (amino acid) used to build the channel. Specifically, the mutation replaces the amino acid glycine with the amino acid arginine at position 406 (written as Gly406Arg or G406R).

The mutation that causes classic Timothy syndrome occurs in exon 8A, and is present only in the version of the CaV1.2 channel made with this segment. Therefore, in the brain and heart, the mutation affects about 20 percent of all CaV1.2 channels.

Two mutations in the CACNA1C gene cause a more severe, atypical form of Timothy syndrome called type 2. These mutations occur in the version of the CaV1.2 channel made with exon 8. One of these genetic changes, G406R, is the same mutation that causes classic Timothy syndrome when it occurs in exon 8A. The other mutation replaces the amino acid glycine with the amino acid serine at position 402 (written as Gly402Ser or G402S).

Because the mutations responsible for atypical Timothy syndrome occur in exon 8, they are present only in versions of the CaV1.2 gene that contain this segment. In the brain and heart, this version accounts for about 80 percent of all CaV1.2 channels. Researchers believe that the more severe features of atypical Timothy syndrome result from the higher percentage of mutated channels in heart and brain cells.

Mutations in the CACNA1C gene change the structure of CaV1.2 channels throughout the body. The altered channels stay open much longer than usual, which allows calcium ions to continue flowing into cells abnormally. The resulting overload of calcium ions within cardiac muscle cells changes the way the heart beats and can cause arrhythmia. Researchers are working to determine how an increase in calcium ion transport in other tissues, including cells in the brain, underlies the other features of Timothy syndrome.

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CACNA1C gene - Genetics Home Reference - NIH

Mutations in the HFE gene can increase the risk of developing a condition called porphyria. Porphyria is a group of disorders caused by abnormalities in the chemical steps that lead to heme production. Heme is a vital molecule for all of the body's organs, although it is most abundant in the blood, bone marrow, and liver. Heme is a component of several iron-containing proteins called hemoproteins, including hemoglobin (the protein that carries oxygen in the blood). HFE gene mutations are found more frequently in people with the most common form of porphyria, known as porphyria cutanea tarda, than in unaffected people.

Researchers suspect that HFE gene mutations may trigger this type of porphyria by increasing the absorption of iron. A buildup of excess iron, in combination with other genetic and nongenetic factors, interferes with the production of a molecule called heme. Heme is a component of iron-containing proteins called hemoproteins, including hemoglobin (the protein that carries oxygen in the blood). A blockage in heme production allows other compounds called porphyrins to build up to toxic levels in the liver and other organs. These compounds are formed during the normal process of heme production, but excess iron and other factors allow them to accumulate to toxic levels. The abnormal buildup of porphyrins leads to the characteristic features of porphyria cutanea tarda.

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HFE gene - Genetics Home Reference - NIH

Some gene mutations are acquired during a person's lifetime and are present only in certain cells. These changes, which are called somatic mutations, are not inherited. Somatic mutations in the JAK2 gene are associated with essential thrombocythemia, a disorder characterized by an increased number of platelets, the blood cell fragments involved in normal blood clotting. The most common mutation (written as Val617Phe or V617F) replaces the protein building block (amino acid) valine with the amino acid phenylalanine at position 617 in the protein. This particular mutation is found in approximately half of people with essential thrombocythemia. A small number of affected individuals have a somatic mutation in another part of the JAK2 gene known as exon 12.

The V617F JAK2 gene mutation results in the production of a JAK2 protein that is constantly turned on (constitutively activated), which, in essential thrombocythemia, leads to the overproduction of abnormal blood cells called megakaryocytes. Because platelets are formed from megakaryocytes, the overproduction of megakaryocytes results in an increased number of platelets. Excess platelets can cause abnormal blood clotting (thrombosis), which leads to many signs and symptoms of essential thrombocythemia.

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JAK2 gene - Genetics Home Reference - NIH

More than 1,100 mutations in the TSC2 gene have been identified in individuals with tuberous sclerosis complex, a condition characterized by developmental problems and the growth of noncancerous tumors in many parts of the body. Most of these mutations insert or delete a small number of DNA building blocks (base pairs) in the TSC2 gene. Other mutations change a single base pair in the TSC2 gene or create a premature stop signal in the instructions for making tuberin.

People with TSC2-related tuberous sclerosis complex are born with one mutated copy of the TSC2 gene in each cell. This mutation prevents the cell from making functional tuberin from that copy of the gene. However, enough tuberin is usually produced from the other, normal copy of the TSC2 gene to regulate cell growth effectively. For some types of tumors to develop, a second mutation involving the other copy of the gene must occur in certain cells during a person's lifetime.

When both copies of the TSC2 gene are mutated in a particular cell, that cell cannot produce any functional tuberin. The loss of this protein allows the cell to grow and divide in an uncontrolled way to form a tumor. A shortage of tuberin also interferes with the normal development of certain cells. In people with TSC2-related tuberous sclerosis complex, a second TSC2 gene mutation typically occurs in multiple cells over an affected person's lifetime. The loss of tuberin in different types of cells disrupts normal development and leads to the growth of tumors in many different organs and tissues.

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TSC2 gene - Genetics Home Reference - NIH

Cheadle JP, Sampson JR. Exposing the MYtH about base excision repair and human inherited disease. Hum Mol Genet. 2003 Oct 15;12 Spec No 2:R159-65. Epub 2003 Aug 5. Review.

Croitoru ME, Cleary SP, Di Nicola N, Manno M, Selander T, Aronson M, Redston M, Cotterchio M, Knight J, Gryfe R, Gallinger S. Association between biallelic and monoallelic germline MYH gene mutations and colorectal cancer risk. J Natl Cancer Inst. 2004 Nov 3;96(21):1631-4.

Farrington SM, Tenesa A, Barnetson R, Wiltshire A, Prendergast J, Porteous M, Campbell H, Dunlop MG. Germline susceptibility to colorectal cancer due to base-excision repair gene defects. Am J Hum Genet. 2005 Jul;77(1):112-9. Epub 2005 May 3.

Fleischmann C, Peto J, Cheadle J, Shah B, Sampson J, Houlston RS. Comprehensive analysis of the contribution of germline MYH variation to early-onset colorectal cancer. Int J Cancer. 2004 Apr 20;109(4):554-8.

Jones S, Emmerson P, Maynard J, Best JM, Jordan S, Williams GT, Sampson JR, Cheadle JP. Biallelic germline mutations in MYH predispose to multiple colorectal adenoma and somatic G:C-->T:A mutations. Hum Mol Genet. 2002 Nov 1;11(23):2961-7.

Jones S, Lambert S, Williams GT, Best JM, Sampson JR, Cheadle JP. Increased frequency of the k-ras G12C mutation in MYH polyposis colorectal adenomas. Br J Cancer. 2004 Apr 19;90(8):1591-3.

Kambara T, Whitehall VL, Spring KJ, Barker MA, Arnold S, Wynter CV, Matsubara N, Tanaka N, Young JP, Leggett BA, Jass JR. Role of inherited defects of MYH in the development of sporadic colorectal cancer. Genes Chromosomes Cancer. 2004 May;40(1):1-9.

Lipton L, Halford SE, Johnson V, Novelli MR, Jones A, Cummings C, Barclay E, Sieber O, Sadat A, Bisgaard ML, Hodgson SV, Aaltonen LA, Thomas HJ, Tomlinson IP. Carcinogenesis in MYH-associated polyposis follows a distinct genetic pathway. Cancer Res. 2003 Nov 15;63(22):7595-9.

Lipton L, Tomlinson I. The multiple colorectal adenoma phenotype and MYH, a base excision repair gene. Clin Gastroenterol Hepatol. 2004 Aug;2(8):633-8. Review.

Russell AM, Zhang J, Luz J, Hutter P, Chappuis PO, Berthod CR, Maillet P, Mueller H, Heinimann K. Prevalence of MYH germline mutations in Swiss APC mutation-negative polyposis patients. Int J Cancer. 2006 Apr 15;118(8):1937-40.

Sampson JR, Dolwani S, Jones S, Eccles D, Ellis A, Evans DG, Frayling I, Jordan S, Maher ER, Mak T, Maynard J, Pigatto F, Shaw J, Cheadle JP. Autosomal recessive colorectal adenomatous polyposis due to inherited mutations of MYH. Lancet. 2003 Jul 5;362(9377):39-41.

Sampson JR, Jones S, Dolwani S, Cheadle JP. MutYH (MYH) and colorectal cancer. Biochem Soc Trans. 2005 Aug;33(Pt 4):679-83. Review.

Sieber OM, Lipton L, Crabtree M, Heinimann K, Fidalgo P, Phillips RK, Bisgaard ML, Orntoft TF, Aaltonen LA, Hodgson SV, Thomas HJ, Tomlinson IP. Multiple colorectal adenomas, classic adenomatous polyposis, and germ-line mutations in MYH. N Engl J Med. 2003 Feb 27;348(9):791-9.

Venesio T, Molatore S, Cattaneo F, Arrigoni A, Risio M, Ranzani GN. High frequency of MYH gene mutations in a subset of patients with familial adenomatous polyposis. Gastroenterology. 2004 Jun;126(7):1681-5.

Wang L, Baudhuin LM, Boardman LA, Steenblock KJ, Petersen GM, Halling KC, French AJ, Johnson RA, Burgart LJ, Rabe K, Lindor NM, Thibodeau SN. MYH mutations in patients with attenuated and classic polyposis and with young-onset colorectal cancer without polyps. Gastroenterology. 2004 Jul;127(1):9-16. Erratum in: Gastroenterology. 2004 Nov;127(5):1651.

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MUTYH gene - Genetics Home Reference - NIH