Category Archives: Human Genetics

Table of Contents

The human karyotype | Human chromosomal abnormalities

Human allelic disorders (recessive) | Human allelic disorders (dominant)

Sex-linked traits | Diagnosis of human genetic diseases | Radioactive probes

Links

There are 44 autosomesand 2 sex chromosomes in the human genome, for a total of 46. Karyotypesare pictures of homologous chromosomes lined up together during Metaphase I of meiosis. The chromosome micrographs are then arranged by size and pasted onto a sheet.

Click here for a larger picture. This picture is from The Primate Cytogenetics Network at ( http://www.selu.com/~bio/cyto/karyotypes/Hominidae/Hominidae.html).

A common abnormality is caused by nondisjunction, the failure of replicated chromosomes to segregate during Anaphase II. A gamete lacking a chromosome cannot produce a viable embryo. Occasionally a gamete with n+1 chromosomes can produce a viable embryo.

In humans, nondisjunction is most often associated with the 21st chromosome, producing a disease known as Down's syndrome (also referred to as trisomy21). Sufferers of Down's syndrome suffer mild to severe mental retardation, short stocky body type, large tongue leading to speech difficulties, and (in those who survive into middle-age), a propensity to develop Alzheimer's Disease. Ninety-five percent of Down's cases result from nondisjunction of chromosome 21. Occasional cases result from a translocationin the chromosomes of one parent. Remember that a translocation occurs when one chromosome (or a fragment) is transferred to a non-homologous chromosome. The incidence of Down's Syndrome increases with age of the mother, although 25% of the cases result from an extra chromosome from the father. Click hereto view a drawing (from Bioweb) of a karyotype of Down's syndrome.

Sex-chromosome abnormalities may also be caused by nondisjunction of one or more sex chromosomes. Any combination (up to XXXXY) produces maleness. Males with more than one X are usually underdeveloped and sterile. XXX and XO women are known, although in most cases they are sterile. What meiotic difficulties might a person with Down's syndrome or extra sex-chromosomes face?

The rest is here:
M.J. Farabee: Human Genetics - Estrella Mountain Community ...

Feb 06, 2014 Messenger were RNAs charted, with A's and I's representing specific nucleotides. ADR-1 does not alter editing activity of ADR-2 at all of the hundreds of newly found editing sites, but the ability of ADR-1 to bind to these mRNAs is required for its regulatory activity at the majority of ADR-1 affected editing sites. Credit: Heather A. Hundley

Molecular biologists from Indiana University are part of a team that has identified a protein that regulates the information present in a large number of messenger ribonucleic acid molecules that are important for carrying genetic information from DNA to protein synthesis.

The new work, published today in Cell Reports, finds that the protein ADR-1 binds to messenger ribonucleic acid, or mRNA, and then enhances RNA editing, a process that allows a gene to be present as multiple mRNAs that can then each affect gene expression differently.

Organisms ranging from sea anemone to humans utilize RNA editing to express different mRNAs at various times in development. Decreased mRNA editing has been reported in patients with neuropathological diseases like epilepsy, schizophrenia, amyotrophic lateral sclerosis and several types of cancer, including glioblastomas (brain tumors).

Using the model organism, Caenorhabditis elegans, the researchers identified over 400 new mRNA editing sitesthe majority regulated by ADR-1and declared the protein the first global regulator of RNA editing.

"What we've determined is that this protein's ability to alter editing of mRNAs is not specific to just a few genes, but instead, its ability to bind to mRNAs is required for proper RNA editing of most mRNAs," said Michael C. Washburn, a graduate student in the IU College of Arts and Sciences' Department of Biology and first author on the paper with Boyko Kakaradov of the University of California, San Diego.

Working in the laboratory of Heather A. Hundley, corresponding author on the paper and an assistant professor of biochemistry and molecular biology in the IU School of Medicine's Medical Sciences Program at Bloomington, Washburn and undergraduate Medical Sciences program student Emily Wheeler collaborated with the team from UCSD to show that the region of ADR-1 protein that binds to target mRNAs in C. elegans is also required for regulating editing. This region is present in many human proteins, and a protein similar to ADR-1 is specifically expressed in human neurons.

"So it is likely that a similar mechanism exists to regulate editing in humans," Hundley said. "Further work in our lab will be aimed at understanding the detailed mechanism of how these proteins regulate editing, in turn providing an inroad to developing therapeutics that modulate editing for the treatment of human diseases."

C. elegans is a microscopic worm that like humans highly expresses a family of proteins in the nervous system called ADARsadenosine deaminases that act on RNAa family that includes ADR-1.

ADARs change specific nucleotides (molecular building blocks for DNA and RNA) in RNA, in a process called adenosine-to-inosine editing, or A-to-I editing, that diversifies genetic information to specify different amino acids, splice sites and structures. Scientists currently estimate there are between 400,000 and 1 million A-to-I editing events in noncoding regions of the human transcriptome.

Go here to read the rest:
A key facilitator of mRNA editing uncovered

Researchers from the University of Washington and the HudsonAlpha Institute for Biotechnology have developed a new method for organizing and prioritizing genetic data. The Combined Annotation-Dependent Depletion, or CADD, method will assist scientists in their search for disease-causing mutation events in human genomes.

The new method is the subject of a paper titled "A general framework for estimating the relative pathogenicity of human genetic variants," published in Nature Genetics.

Current methods of organizing human genetic variation look at just one or a few factors and use only a small subset of the information available. For example, the Encyclopedia Of DNA Elements, or ENCODE, catalogs various types of functional elements in human genomes, while sequence conservation looks for similar or identical sequences that have survived across different species through hundreds of millions of years of evolution. CADD brings all of these data together, and more, into one score in order to provide a ranking that helps researchers discern which variants may be linked to disease and which ones may not.

"CADD will substantially improve our ability to identify disease-causal mutations, will continue to get better as genomic databases grow, and is an important analytical advance needed to better exploit the information content of whole-genome sequences in both clinical and research settings," said Gregory M. Cooper, Ph.D., faculty investigator at HudsonAlpha and one of the collaborators on CADD.

The goal in developing the new approach was to take the overwhelming amount of data available and distill it down into a single score that can be more easily evaluated by a researcher or clinician. To accomplish that, CADD compares and contrasts the properties of 15 million genetic variants separating humans from chimpanzees with 15 million simulated variants. Variants observed in humans have survived natural selection, which tends to remove harmful, disease-causing variants, while simulated variants are not exposed to selection. Thus, by comparing observed to simulated variants, CADD is able to identify those properties that make a variant harmful or disease-causing. C scores have been pre-computed for all 8.6 billion possible single nucleotide variants and are freely available for researchers.

"We didn't know what to expect," Cooper said, "but we were pleasantly surprised that CADD was able not only to be applicable to mutations everywhere in the genome but in fact do a substantially better job in nearly every test that we performed than other metrics."

The CADD method is unique from other algorithms in that it assigns scores to mutations anywhere in human genomes, not just the less-than two percent that encode proteins (the "exome"). This unique attribute will be crucial as whole-genome sequencing becomes routine in both clinical and research settings.

Story Source:

The above story is based on materials provided by HudsonAlpha Institute for Biotechnology. Note: Materials may be edited for content and length.

View original post here:
Ranking disease-causal mutations within whole genome sequences

Regents push for change in genetic medicine

BY KEVIN SVEC | FEBRUARY 06, 2014 5:00 AM

What was once confined only to science-fiction movies is now the subject of boardroom meetings. The University of Iowa Carver College of Medicine, the home to the Iowa Institute of Human Genetics, plans to start a revolution in modern medicine. Today, most of the medication prescribed is based on the weight and body surface area of the patient. The institutes goal is to promote an alternative, which will be known as personal genomic medicine.

Such medicine would cater to each patients specific needs. The medication prescribed would be based on the genetic makeup of a patient rather than her or his body index.

Using a genetic test, scientists would be able to evaluate each patients needs, allowing health-care providers to personalize each drug treatment.

The medicine will work with each individual patient based on her or his personal health risks. By personalizing the medicine, the doctors could increase the likelihood that the drug would have the best possible effect on each patient.

Richard Smith, the director of the Institute of Human Genetics, noted several advantages of genomic medicine.

Newborns would be able to have screenings done to determine what medication would work best from the beginning, said Smith.

According to the Jackson Laboratory website, any prescription drug now on the market only works for half of the people who take it. Antidepressants are effective for only 63 percent of those who take it. The percentage rate of effectiveness jumps to 75 percent among cancer patients. Genetic testing can change that.

Part of the process has started already. For those willing to pay, they can have their genes tested. The cost for the test is $296 through the UI Hospitals and Clinics, $256 through the institute. However, Medicare is willing to pay for $295 of the costs.

See the article here:
Regents push for change in genetic medicine

Human genetics is the branch that studies the aspect of 'inheritance' in formation of human beings. Its study makes it easier to understand the cause of certain disorders, behavioral issues and development.

The Importance of Housekeeping Genes

Housekeeping genes are those that are always expressed in all cells of an organism, and are important for the maintenance of basic or 'housekeeping' functions of the cell. This Buzzle write-up provides a brief account of the same.

Pros and Cons of Gene Patenting

Gene patenting is quite common in the medical field today, however, it is still surrounded by many controversies. In this Buzzle article, we will discuss what is gene patenting and what are its positive and negative aspects.

Pros and Cons of Designer Babies

Designer babies are babies, whose genetic makeup has been artificially screened and chosen by scientists, via genetic engineering. This concept has raised numerous ethical issues. Let's have a look at the pros and cons of designer...

DNA Replication Steps

The process of DNA replication comprises a set of carefully orchestrated sequence of events to duplicate the entire genetic content of a cell. The current article provides a short insight into the complex DNA replication steps.

Incomplete Dominance Examples

Read more:
Human Genetics - Buzzle

Dr Olufunmilayo Olopade

Olufunmilayo I. Olopade is an hematology oncologist, Associate Dean for Global Health and Walter L. Palmer Distinguished Service Professor in Medicine and Human genetics at the University of Chicago.

Born in 1957 shealso serves as director of the University of Chicago Hospitals Cancer Risk Clinic.

She graduated from University of Ibadan, Nigeria, with a MD, in 1980. She has performed extensive clinical work surrounding the role of the BRCA1 and BRCA2 genes in the incidence of breast cancer in women of African descent.

She is a member of the American Association for Cancer Research, the American College of Physicians, and the Nigerian Medical Association and works closely with the Breast Cancer Research Foundation. She is a member of the Institute of Medicine.

She married Christopher Sola Olopade, also a physician at the University of Chicago, in 1983; they have two daughters, and one son.

In 2011, President Barack Obama, appointed herto the US Cancer advisory board.

Dr. Olopade is also passionate about exploring the genetic factors behind disparities in breast cancer that affect women of African descent.

Read more here:
Meet Olufunmilayo Olopade, Nigerias gift to the world

PHOENIX (CBS5) -

Phoenix-based scientists at TGen are beginning to examine whether dogs might hold the key to unlocking the mystery behind childhood autism.

The non-profit genomics organization is raising funds to initiate a study looking at doggie DNA they hope will translate into possible life improving advancements for children suffering from autism.

"Science has been studying the genetics of autism for a very long time," says Matt Huentleman, PhD with TGen.

TGen has had success in the past studying K-9 DNA and getting results translated to help humans.

"This type of breed has a cancer that is similar to the human version," says dog breeder Valana Wells.

Wells breeds Clumber Spaniels, a British hunting dog. Several years ago she submitted the DNA of one of her dogs for a cancer research study. Scientists seek out the DNA from purebred dogs because it is, they say, a hundred times simpler to analyze than human DNA.

In the autism study, researchers are looking to establish a link between obsessive compulsive behavior in certain dog breeds with the autism markers in a human.

"The hope is if we can identify the genes that might be linked to that type of behavior. That type of obsessive compulsive behavior, then that becomes a significant candidate gene for human autism," says Dr. Huentleman.

Researchers share the results of what they find with the dog owners who submit DNA.

Read more:
Researchers look to K-9 DNA to identify human autism genes

Hairiness -- allowing adaptation to warmer environments -- was among gains

Roughly 500,000 year ago, the breeding populations that would evolve into humans (Homo sapiens) and Neanderthals (Homo neanderthalensis) separated. Neanderthals came to dominate the mountainous, forest terrain of Europe, while humans spread out across the warm grasslands of Africa and the Middle East. But the long estranged relatives would come into contact in an intimate way once more when mankind thrust its way into Europe roughly 80,000 years ago. And by intimate, yes, we mean there was sex. I. Understanding Our Shared Family Secret -- Neanderthal Sex Ever since researcher and entrepreneur J. Craig Venter, Ph.D. became the first human to have his or her genome sequenced in 2007, the race was on to sequence the Neanderthal genome and find what secrets it might hold. Led by led by the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany and its top ancient-DNA expert, Svante Pbo, the project yielded a draft genome in May 2010, followed by a "finished" Neanderthal genome in March 2013. With the initial 2010 announcement, definitive proof of our ancestors' steamy romance with European Neanderthals was laid bare for the first time. Today researchers are still worker to chronicle that mysterious engagement and what impacts it has on modern human genetics. Harvard Medical School (HMS) geneticist Professor David Reich's lab -- working with collaborators at the Max Planck Institute -- is the latest to offer new insight into this relationship.

It suggests the introduction of some of these Neanderthal mutations was harmful to the ancestors of non-Africans and that these mutations were later removed by the action of natural selection.

Now that we can estimate the probability that a particular genetic variant arose from Neanderthals, we can begin to understand how that inherited DNA affects us. We may also learn more about what Neanderthals themselves were like. [The barren DNA stretches] suggest that when ancient humans met and mixed with Neanderthals, the two species were at the edge of biological incompatibility. It is fascinating that these types of problems could arise over that short a time scale.

The researchers next goals include making tests for the Neanderthal genes identified available to the public, enhancing the hunt for Neanderthal genomes by sequencing other Neanderthals' full gene sequences, and sequencing the DNA of Denisovans (Denisova hominins) -- another close relative of man that bread with early humans in Oceania.

The ongoing research is funded by the Max Planck Institute, the Howard Hughes Medical Institute (HHMI), the National Science Foundation, and the National Institutes of Health (NIH).

Sources: Nature, Science, Harvard Medical School

More here:
Neanderthal-Human Breeding Was Hard, But Yielded Benefits

A pair of scientific studies using the latest genetic evidence are seeking to identify the very first man to walk the Earth, the so-called "Adam."

The studies delve into phylogenetics, a forensic hunt through the Xs and Ys of our chromosomes to find the genetic Adam, to borrow the name from the Bible. And Eran Elhaik from the University of Sheffield says he knows exactly when that first man lived.

"We can say with some certainty that modern humans emerged in Africa a little over 200,000 years ago," Elhaik said in a press release. That directly contradicts a March 2013 studyfrom Arizona Research Labs at the University of Arizona, which found that the human Y chromosome (the hereditary factor determining male sex) originated through interbreeding among species and dates back even further than 200 millennia.

"Our analysis indicates this lineage diverged from previously known Y chromosomes about 338,000 years ago, a time when anatomically modern humans had not yet evolved," said Michael Hammer, an associate professor in the University of Arizona's Department of Ecology and Evolutionary Biology.

Elhaik published a paper in the January 2014 issue of the European Journal of Human Genetics on his work; he used the opportunity to take a swipe at Hammer's paper, published in the American Journal of Human Genetics.

"We have shown that the University of Arizona study lacks any scientific merit," Elhaik claimed. "In fact, their hypothesis creates a sort of 'space-time paradox' whereby the most ancient individual belonging to the Homo sapiens species has not yet been born."

Think of the Michael J. Fox film, Back to the Future. Marty was worried that his parents would not meet and so he would not be born in the future. "It's the same idea," Elhaik said.

Hammer told FoxNews.com he stands by his work.

The paper by Elhaik and colleagues does not present a convincing argument against our paper and unfortunately at times appears to display a lack of technical understanding of the subject area. We are in the process of submitting a rebuttal," he said.

Identifying the very first Y chromosome of a genetic Adam would not mean scientists had located the Biblical figure Adam, explained Werner Arber, the Vaticans top scientist, told FoxNews.com.

Read the original here:
'Man'-hunt for 'Adam'

Popped Like a Balloon (The Hidden: Source)
What is The Hidden? In the early 1950s human genetics experimentation was taking its first, tentative steps. Amongst many other black projects, a team of Bri...

By: PinkVanManGang

Read more here:
Popped Like a Balloon (The Hidden: Source) - Video