Basic Understanding of Genetics

Genetic testing uses laboratory methods to look at your genes, which are the DNA instructions you inherit from your mother and your father.

Genetic tests may be used to identify increased risks of health problems, to choose treatments, or to assess responses to treatments. Now I know nothing about this so I phoned a UK Company and asked can you help me help the Parents to understand better. They gave me the following info, so you the Parents can learn and maybe understand a wee bit better than you once did.

What you find is very interesting, and proves if you ask for help 9 times out of 10 people in the know are more than willing to help out.

What is DNA? What is a gene? What are Chromosomes?

Whatever you want to know about genetics you’ll find it all here, in helpful bite-size chunks.

The resources on this site should not be used as a substitute for professional medical care or advice.

Genetic Testing

Over the course of the last decade, the definitions of health and disease have been transformed by advances in genetics. Genetic testing has enabled researchers and clinicians to detect inherited traits, diagnose heritable conditions, determine and quantify the likelihood that a heritable disease will develop, and identify genetic susceptibility to familial disorders. Many of the strides made in genetic diagnostics are direct results of the Human Genome Project, an international thirteen-year effort begun in 1990 by the U.S. Department of Energy and the National Institutes of Health, which mapped and sequenced the human genome in its entirety. The increasing availability of genetic testing has been one of the most immediate applications of this groundbreaking research.

A genetic test is an analysis of human deoxyribonucleic acid (DNA), ribonucleic acid (RNA), chromosomes, and proteins to detect heritable disease-related genotypes, mutations, phenotypes, or karyotypes (standard pictures of the chromosomes in a cell) for the purposes of diagnosis, treatment, and another clinical decision making. Most genetic testing is performed by drawing a blood sample and extracting DNA from white blood cells. Genetic tests may detect mutations at the chromosomal level, such as additional, absent, or rearranged chromosomal material, or even subtle abnormalities such as a substitution in one of the bases that make up the DNA. There is a broad range of techniques that can be used for genetic testing. Genetic tests have diverse purposes, including screening for and diagnosis of genetic disease in newborns, children, and adults; the identification of future health risks; the prediction of drug responses; and the assessment of risks to future children.

There is a difference between genetic tests performed to screen for disease and testing conducted to establish a diagnosis. Diagnostic tests are intended to definitively determine whether a patient has a particular problem. They are generally complex tests and commonly require sophisticated analysis and interpretation. They may be expensive and are generally performed only on people believed to be at risk, such as patients who already have symptoms of a specific disease.

In contrast, screening is performed on healthy, asymptomatic (showing no symptoms of disease) people and often to the entire relevant population. A good screening test is relatively inexpensive, easy to use and interpret, and helps identify which individuals in the population are at higher risk of developing a specific disease. By definition, screening tests identify people who need further testing or those who should take special preventive measures or precautions. For example, people who are found to be especially susceptible to genetic conditions with specific environmental triggers are advised to avoid the environmental factors linked to developing the disease.

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What are the types of genetic tests?

Genetic Testing: What You Should Know?

(Go to the bottom of this website below, many many links to this subject very interesting reading)

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What does genetic testing involve?

Genetic testing usually involves having a sample of your blood or tissue taken. The sample will contain cells containing your DNA and can be tested to find out whether you are carrying a particular mutation and are at risk of developing a particular genetic condition.

In some cases, genetic testing can be carried out to see if a foetus is likely to be born with a certain genetic condition by testing samples of amniotic fluid (the fluid that surrounds the foetus in the womb) or chorionic villi cells (cells that develop into the placenta) extracted from the mother’s womb using a needle.

Depending on the condition(s) being tested for, the blood or cell samples will then be tested and examined in a genetics laboratory to check for a specific gene, a certain mutation on a specific gene or any mutation on a specific gene.

How genetic conditions are inherited

Each cell in the body contains 23 pairs of chromosomes. One chromosome from each pair is inherited from your mother and one is inherited from your father.

The chromosomes contain the genes you inherit from your parents. There may be different forms of the same gene – called alleles.

For example, for the gene that determines eye color, you may inherit a brown allele from your mother and a blue allele from your father. In this instance, you will end up with brown eyes because brown is the dominant allele. The different forms of genes are caused by mutations (changes) in the DNA code.

The same is true for medical conditions. There may be a faulty version of a gene that results in a medical condition, and a normal version that may not cause health problems.

Welcome to UKGTN

The UK Genetic Testing Network is an advisory organization that provides commissioning support to the NHS and DH for NHS patients in the  UK CLICK ON THIS LINK

Genetic Disorders A to Z

and related genes and chromosomes Find a specific condition or related topic by the first letter: CLICK HERE

Genes click here:

Chromosomes Information about specific chromosomes: CLICK HERE

Concepts & Tools

for understanding human genetics: Handbook Help Me Understand Genetics: CLICK HERE:


Genetics Home Reference 

More than 1,100 health conditions, diseases, and syndromes

obtains definitions from several sources: CLICK HERE:

Resources and Patient Support

Each of the following categories provides links to relevant genetics resources on the web. CLICK HERE:

Genomics England is delivering the 100,000 Genomes Project.

We are creating a new genomic medicine service with the NHS – to support better diagnosis and better treatments for patients. We are also enabling medical research.

The 100,000 Genomes Project

The project will sequence 100,000 genomes from around 70,000 people. Participants are NHS patients with a rare disease, plus their families, and patients with cancer.

What does SWAN / being undiagnosed mean?

SWAN stands for Syndrome Without A Name.

It is a term used to describe disabled children who are thought to have a genetic syndrome or condition that doctors have so far been unable to identify.  Many of these children have had lots of tests including blood tests, microarray, lumbar punctures, EEG’s, ECG’s and MRI’s but they have all come back negative.

What is the DDD study?

Locations of the Regional Genetics Services

The Deciphering Developmental Disorders (DDD) study aims to find out if using new genetic technologies can help doctors understand why patients get developmental disorders. To do this we have brought together doctors in the 24 Regional Genetics Services, throughout the UK and Republic of Ireland, with scientists at the Wellcome Trust Sanger Institute, a charitably funded research institute which played a world-leading role in sequencing (reading) the human genome. The DDD study involves experts in clinical, molecular and statistical genetics, as well as ethics and social science. It has a Scientific Advisory Board consisting of scientists, doctors, a lawyer and patient representative, and has received National ethical approval in the UK.

The DDD study is jointly funded by the Health Innovation Challenge Fund – a parallel funding partnership between the Wellcome Trust and the UK Department of Health – and the Wellcome Trust Sanger Institute and is supported by the NHS National Institute for Health Research.

Dr. Helen Firth, Consultant Clinical Geneticist at Addenbrooke’s Hospital, Cambridge, says:

“Deciphering Development Disorders offers a win-win to patients, clinicians and scientists alike. It could significantly improve our understanding and management of these rare conditions and provide new avenues of research into treatments for scientists to pursue.”

We have spent four years collecting DNA and clinical information from over 12,000 undiagnosed children and adults in the UK with developmental disorders and their parents. The DDD team is absolutely committed to analyzing and re-analyzing all the genomic data from families in the study over the coming years to try to find a diagnosis for as many children as possible. Recruitment of new patients into DDD ended on April 3rd, 2015, but the DDD team is working closely with the NHS and Genomics England to ensure that this type of genetic testing is continued for families with developmental disorders in the future.


Very interesting

Data sharing is a fundamental part of DDD to aid diagnoses and discoveries in the future. We aim to publish as much of our research as possible in peer-reviewed publications to increase the understanding of developmental disorders. Below is the list of DDD manuscripts published so far. They include papers describing our methods and key findings, as well as manuscripts specialising in individual genes or specific developmental disorders.

What is neurofibromatosis type 1?

Neurofibromatosis type 1 is a condition characterized by changes in skin coloring (pigmentation) and the growth of tumors along nerves in the skin, brain, and other parts of the body. The signs and symptoms of this condition vary widely among affected people.

Beginning in early childhood, almost all people with neurofibromatosis type 1 have multiple café-au-lait spots, which are flat patches on the skin that are darker than the surrounding area. These spots increase in size and number as the individual grows older. Freckles in the underarms and groin typically develop later in childhood.

During childhood, benign growths called Lisch nodules often appear in the colored part of the eye (the iris). Lisch nodules do not interfere with vision. Some affected individuals also develop tumors that grow along the nerve leading from the eye to the brain (the optic nerve). These tumors, which are called optic gliomas, may lead to reduced vision or total vision loss. In some cases, optic gliomas have no effect on vision.

Additional signs and symptoms of neurofibromatosis type 1 include high blood pressure (hypertension), short stature, an unusually large head (macrocephaly), and skeletal abnormalities such as an abnormal curvature of the spine (scoliosis). Although most people with neurofibromatosis type 1 have normal intelligence, learning disabilities and attention deficit hyperactivity disorder (ADHD) occur frequently in affected individuals.

Frequently Asked Questions About Genetic Testing

About Genetics

Now I know nothing about this so I phoned a UK Company and asked can you help me help the Parents to understand better.

They gave me the following info, so you the Parents can learn and maybe understand a wee bit better than you once did.

What you find is very interesting, and proves if you ask for help 9 times out of 10 people in the

know are more than willing to help out.

What is DNA? What is a gene? Whatever you want to know about genetics you’ll find it all here, in helpful bite-size chunks.

About your genome

Your about to ENTER a world of mind-blowing info made easy, click on tabs on the pages lose yourself in this

your genome is the place for you to find out everything you want to know about DNA, genes, and genomes. From the basic biology to the challenging ethical issues, it’s here for you to discover and explore!

your genome is a website that enables you to find out more about genetics and genomics. You’ll be able to find out what a genome is and how we sequence the DNA from an organism. You’ll also be able to explore what genetics can tell us about an individual and a population and why this can sometimes throw up some tricky ethical questions and debates.

The website is produced by the Public Engagement team at the Wellcome Genome Campus near Cambridge in the UK. The campus hosted the UK’s contributions to the Human Genome Project and is home to leading international scientists in the field of genomics from the Wellcome Trust Sanger Institute and EMBL European Bioinformatics Institute. Together we aim to stimulate interest and encourage informed debate about this fast-moving area of biomedical science. We provide accurate information about genomics and have created films, animations, and activities to bring this exciting area of science to life.

What is a genome?

A genome is an organism’s complete set of genetic instructions. Each genome contains all of the information needed to build that organism and allow it to grow and develop.

How do you identify the genes in a genome?

After the sections of DNA sequence have been assembled into a complete genome sequence we need to identify where the genes and key features are, but how do we do this?

What is a genome?

A genome is an organism’s complete set of genetic instructions. Each genome contains all of the information needed to build that organism and allow it to grow and develop.


A timeline depicting the key events in the history of genomics and genetic research alongside those in popular culture. From the discovery of DNA, and the election of Roosevelt, right through to whole genome sequencing and Andy Murray winning Wimbledon for the first time.

What is gene therapy?

Gene therapy is when DNA is introduced into a patient to treat a genetic disease. The new DNA usually contains a functioning gene to correct the effects of a disease-causing mutation.

What is inheritance?

Inheritance is the process by which genetic information is passed on from parent to child. This is why members of the same family tend to have similar characteristics.

What is Down’s syndrome?

Down’s syndrome is a genetic disorder caused by the presence of all or part of an extra copy of chromosome 21.

What is a chromosome disorder?

A chromosome disorder results from a change in the number or structure of chromosomes.

What is antibiotic resistance?

Antibiotic resistance is when bacteria develop the ability to survive exposure to antibiotics designed to kill them or stop their growth.

What is genetic testing?

Genetic testing is an incredibly useful tool for identifying changes or mutations in DNA that could lead to genetic disease.

What is a genetic disorder?

A genetic disorder is a disease that is caused by a change, or mutation, in an individual’s DNA sequence.

DNA (deoxyribonucleic acid) is the set of genetic instructions for creating an organism. DNA molecules are shaped like a spiral staircase called a double helix. Each stair is composed of the DNA bases A, C, T, and G. Some segments of these bases contain sequences, like A-T-C-C-G-A-A-C-T-A-G, which constitute individual genes. Genes determine which proteins individual cells will manufacture, and thus what function particular cells will perform.


Shuffling the Deck

For most of our genome, we receive half of our genes from our father and a half from our mother. Each half represents a shuffled combination of DNA passed down to us from our ancestors. This recombination process makes it difficult to study lines of descent because it creates a genetic mix of everyone who has come before.

Fortunately for anthropological geneticists, there are parts of the genome that are passed down un-shuffled from parent to child. In these segments, the genetic code is varied only through occasional mutations—random spelling mistakes in the long sequence of letters that make up our DNA.

When these mutations are passed down through the generations they become markers of descent.

The Y chromosome

The Y chromosome is the sex-determining chromosome in humans. While all other chromosomes are found in matching pairs, it is the mismatch of the Y with its partner, the X chromosome, that determines gender—men have a mismatched pair (Y and X), while women have two X chromosomes. Because the Y does not have an identical matching chromosome, most of it (the non-recombining region, or NRY) escapes the shuffling process known as recombination that occurs every generation in the rest of our genome. This allows the Y to be passed down through a purely male line, changed only by random mutational events.

The human body is made of some 50 trillion to 100 trillion cells,

The human body is made of some 50 trillion to 100 trillion cells, which form the basic units of life and combine to form more complex tissues and organs. Inside each cell, genes make up a blueprint for protein production that determines how the cell will function. Genes also determine physical characteristics or traits. The complete set of some 20,000 to 25,000 genes is called the genome. Only a tiny fraction of the total genome sets the human body apart from those of other animals.

Most cells have a similar basic structure. An outer layer, called the cell membrane, contains a fluid called cytoplasm. Within the cytoplasm are many different specialized “little organs” called organelles. The most important of these is the nucleus, which controls the cell and houses the genetic material in structures called chromosomes. Another type of organelle is mitochondrion. These cellular power plants have their own genome and do not recombine during reproduction.