Category Archives: Human Genetics

Credit: University of Manchester An international collaboration led by scientists and doctors from the UK, Netherlands and United States has identified a new genetic disease that affects the size of our brains and causes severe developmental problems. While working on another project, Dr Siddharth Banka who is based at The University of Manchester and the Manchester Centre for Genomic Medicine, Saint Mary's Hospital, noticed three children with large or small brains, developmental delay and mutations in a gene called RAC1. At that point, it was difficult to be sure if it was a true finding, because RAC1 has never before been linked to human disease. And mutations in no other single gene have previously shown this extent of variability in brain-size. As part of a parallel project, Professor Han Brunner and Dr Margot Reijnders of the Radboud University in Nijmegen had gathered together four more children with mutations in the same gene and altered brain-sizes. Some of the affected children were also found to have epilepsy and heart defects. Dr Tom Millard also from The University of Manchester then used mouse cells to show that mutations in RAC1 affect the shape of the cells. When Dr Maria Kousi and Professor … Continue reading →

A better understanding of the cause of autism may come from an unlikely source,eurological studies of the fruit fly. Neuroscientists working in the biology department at the University of Nevada, Reno have identified a new genetic mechanism they believe is responsible for disruption of the brain pathways connecting the left and right hemispheres of the brain; which has separately been linked to autism. This is an exciting find, Thomas Kidd, associate professor in the University's biology department, said. In the one striking mutant, called commissureless or comm, there are almost no connections between the two sides of the fruit flys nervous system. The fruit fly nervous system research was conducted in Kidds lab over several years. Fruit flies have brains and nerve cords that form using molecules surprisingly similar to those in human brains and spinal cords. The study, published in the scientific journal PLOS Genetics, shows that the human gene, called PRRG4, functions the same way as the fruit fly Comm at the molecular level, regulating which signals neurons can respond to in their environment. The Comm gene was thought to be unique to insects but our work shows that it is not, Elizabeth Justice, lead author of the … Continue reading →

By: IANS | London | Updated: September 3, 2017 7:01 pm The researchers expect this mechanism to help and play a role in a much larger proportion for patients with intellectual disabilities. (Source: Thinkstock Images) Researchers have discovered 15 genes that play a role in the development of intellectual disabilities. Intellectual disabilities are often caused by a mutation that damages a gene responsible for protein production in cells thus preventing the associated protein from functioning properly. In a number of disease-related genes, it is shown that a de novo mutation does not eliminate the gene, but probably alters its function. To find out how often this mechanism is involved, researchers combined the gene mutations in Dutch patients with a large international database comprising de novo mutations in patients. A de novo mutation is a genetic alteration that is present for the first time in one family member as a result of a variant (or mutation) in a germ cell (egg or sperm) of one of the parents, or a variant that arises in the fertilised egg itself during early embryogenesis. The results of the study, published in the American Journal of Human Genetics, showed 15 genes in which mutations cluster … Continue reading →

Human history is often something modern man only sees as through a glass, darkly. This is particularly the case when that history did not occur in the Mediterranean, the Nile Valley, India, or China, or when there is no written record on which scholars can rely. Exacerbating the disrupting effects of time on history can be when that history occurs in a region where extensive migration has disrupted whatever temporarily stable civilization happened to have taken root at that place at any particular time. But humans leave traces of themselves in their history and a variety of such traces have been the source of reconstructions outside conventional sources. Luigi Cavalli-Sforza began the study of human population genetics as a way to understand this history in 1971 in The Genetics of Human Populations, and later extended these studies to include language and how it influences gene flow between human populations. More recent efforts to use genetics to reconstruct history include Deep Ancestry: The Landmark DNA Quest to Decipher Our Distant Past by Spencer Wells (National Geographic: 2006), and The Seven Daughters of Eve: The Science that Reveals our Genetic Ancestry by Brian Sykes (Carrol & Graf: 2002). And even more recently, … Continue reading →

JTA Parents of children born with Tay-Sachs disease talk about three deaths. There is the moment when parents first learn that their child has been diagnosed with the fatal disease. Then there is the moment when the childs condition has deteriorated so badly blind, paralyzed, non-responsive that he or she has to be hospitalized. Then theres the moment, usually by age 5, when the child finally dies. There used to be an entire hospital unit 16 or 17 beds at Kingsbook Jewish Medical Center in Brooklyn devoted to taking care of these children. It was often full, with a waiting list that admitted new patients only when someone elses child had died. But by the late 1990s that unit was totally empty, and it eventually shut down. Its closure was a visible symbol of one of the most dramatic Jewish success stories of the past 50 years: the near-eradication of a deadly genetic disease. Since the 70s, the incidence of Tay-Sachs has fallen by more than 90 percent among Jews, thanks to a combination of scientific advances and volunteer community activism that brought screening for the disease into synagogues, Jewish community centers and, eventually, routine medical care. Until 1969, when … Continue reading →

In 1944, a Columbia University doctoral student in genetics named Evelyn Witkin made a fortuitous mistake. During her first experiment in a laboratory at Cold Spring Harbor, in New York, she accidentally irradiated millions of E. coli with a lethal dose of ultraviolet light. When she returned the following day to check on the samples, they were all deadexcept for one, in which four bacterial cells had survived and continued to grow. Somehow, those cells were resistant to UV radiation. To Witkin, it seemed like a remarkably lucky coincidence that any cells in the culture had emerged with precisely the mutation they needed to surviveso much so that she questioned whether it was a coincidence at all. Original story reprinted with permission from Quanta Magazine, an editorially independent publication of the Simons Foundation whose mission is to enhance public understanding of science by covering research developments and trends in mathematics and the physical and life sciences. For the next two decades, Witkin sought to understand how and why these mutants had emerged. Her research led her to what is now known as the SOS response, a DNA repair mechanism that bacteria employ when their genomes are damaged, during which dozens … Continue reading →

On Saturday, Sept. 16, Baylor College of Medicine will bring a community conference and resource fair to the Midland area to provide an educational seminar and support materials for children with special needs, as well as their parents. Provided jointly by Baylor and Texas Childrens Hospital, in collaboration with SHARE West Texas, the conference will address the role genetic evaluations play in patients with autism spectrum disorders. Dr. Daryl Scott, associate professor of molecular and human genetics at Baylor, will walk parents through the steps of a genetic evaluation and discuss what the findings mean, citing relevant case studies. The emphasis will be placed on common causes of autism, including Fragile X syndrome, chromosomal abnormalities and mutations affecting genes linked to autism. Conference attendees will learn how new genetic tests have made it possible to determine why some children are affected by autism spectrum disorders. When a specific case is identified, it allows physicians to provide accurate counseling and improved medical care for all family members, Scott said. The resource fair will offer current information on care, education and research as they relate to autism spectrum disorders and encourages networking within the community by connecting patients and their families with … Continue reading →

In an article published in American Journal of Human Genetics on 3 August 2017, an international group of 11 organisations with genetics expertise has issued a joint position statement, setting out 3 key positions on the question of human germline genome editing: (1) At this time, given the nature and number of unanswered scientific, ethical, and policy questions, it is inappropriate to perform germline gene editing that culminates in human pregnancy. (2) Currently, there is no reason to prohibit in vitro germline genome editing on human embryos and gametes, with appropriate oversight and consent from donors, to facilitate research on the possible future clinical applications of gene editing. There should be no prohibition on making public funds available to support this research. (3) Future clinical application of human germline genome editing should not proceed unless, at a minimum, there is (a) a compelling medical rationale, (b) an evidence base that supports its clinical use, (c) an ethical justification, and (d) a transparent public process to solicit and incorporate stakeholder input. This serendipitously timed statement comes on the heels of Shoukhrat Mitalipov and colleagues at Oregon Health and Science Universitys publication of an article in Nature reporting the successful use of … Continue reading →

15 Aug 2017 Genetic forces drive a sizable portion of Alzheimers disease, yet only a fraction of cases thus far are explained by known mutations. A handful of recent papers used genomic sequencing to fish out new variants that, while exceedingly rare, pack a wallop in those who carry them. In the July 24 JAMA Neurology, researchers led by Margaret Pericak-Vance at the University of Miami in Florida reported that mutations in four endolysosomal transport genes boosted risk of early onset AD (EOAD). A few weeks earlier, a large collaboration of French researchers reported rare new TREM2, ABCA7, and SORL1 variants in Neurobiology of Aging, while scientists led by Henne Holstege at VU University Medical Center in Amsterdam characterized the pathogenicity of SORL1 variants and even proposed classifying this endosomal sorting protein as the fourth autosomal-dominant AD gene. A team led by Dominique Campion at University of Rouen, France, dug deep into the well-trodden territory of the three autosomal-dominant genesAPP, PS1, and PS2and uncovered de novo pathogenic variants that cropped up in people with no family history of AD. Last but not least, Anne Rovelet-Lecrux, also at Rouen, linked a duplication in the tau gene to people with an AD … Continue reading →

In an article published in American Journal of Human Genetics on 3 August 2017, an international group of 11 organisations with genetics expertise has issued a joint position statement, setting out 3 key positions on the question of human germline genome editing: (1)At this time, given the nature and number of unanswered scientific, ethical, and policy questions, it is inappropriate to perform germline gene editing that culminates in human pregnancy. (2)Currently, there is no reason to prohibit in vitro germline genome editing on human embryos and gametes, with appropriate oversight and consent from donors, to facilitate research on the possible future clinical applications of gene editing. There should be no prohibition on making public funds available to support this research. (3)Future clinical application of human germline genome editing should not proceed unless, at a minimum, there is (a) a compelling medical rationale, (b) an evidence base that supports its clinical use, (c) an ethical justification, and (d) a transparent public process to solicit and incorporate stakeholder input. This serendipitously timed statement comes on the heels of Shoukhrat Mitalipov and colleagues at Oregon Health and Science Universitys publication of an article in Nature reporting the successful use of CRISPR/Cas9 in human … Continue reading →