The normal human karyotype has two sets of chromosomes, one set inherited from each parent, so that we have 46 chromosomes (22 pairs, including either an XX if you’re a female, or XY if male). But sometimes during cell division of the zygote (early in fertilization), the chromosomes don’t divide properly into their respective cells and the developing fetus carries an abnormal number of chromosomes in all cells of the body (termed aneuploidy). Usually the fetus does not survive into full term, but in some cases when the baby does, a rare chromosome disorder happens.
Trisomy happens when there are …read more

For many of us, GENETICS is a intimidating topic. Don’t worry, I feel the same way around technology and computer language. When we start reading sentences where half the words are foreign, then it can seem way over our heads. And I think people have an idea that genetics is important to medicine and health care, but what role it plays (and how genes act) might be where the questions are.
So that’s why I’m adding a regular feature to explain the basics and call it “What we need to know to get genetics” or something like that. Obviously, this …read more

Imagine having been born from a biological dad, and two biological moms. Wait. Don’t imagine. It’s already happened. For now in monkeys, but who knows someday in humans too. And based on your belief, it’s a “no way!” or a “way to go!”.
How did a three-parent experiment happen?
Scientists from the Oregon National Primate Research successfully transferred the nuclear DNA from one macaque into another cell which had it’s mitochondrial DNA removed (termed mitochondia gene replacement). The hybrid egg cell was fertilized by a sperm and implanted into the uterus of a surrogate mother. Out of the fifteen hybrid …read more

I read about Jessa Perrin’s story and was struck with how her world was turned upside down by a rare disease.
Jessa Perrin was backpacking in Israel when she suddenly became ill. Her skin turned yellow and her liver, kidneys and lungs failed within a day of being admitted to the hospital. She wasn’t even diagnosed with anything yet, but she needed liver transplant fast, or else she was not going to last a week.
The doctors finally diagnosed Jessa with Wilson’s Disease, a rare, recessive genetic disorder that shuts down the body’s ability to get rid of copper. …read more

It’s tough enough for a family to have someone suffer from a genetic disorder but to have three in the family is just heart-breaking. And that’s what the Shaffer family from Oregon is going through as their three young sons are treated for a rare genetic condition that affect the nervous systems (video). Two 8-year old twins and their younger brother have leukodystrophies (adrenoleukodystrophy or ALD), a disorder that causes damage to the membrane (myelin sheath) that surrounds nerve cells in the brain.
Adrenoleukodystrophy is commonly inherited as an X-linked (or sex-linked) trait, as the gene is located on …read more

What do you know when life hits you with a curve ball?
Chicago Cub pitcher Ryan Dempster knows how to throw one in the field. And in real life, he is fighting hard as life hits his family with a curve ball. Dempster’s newborn daughter Riley has been diagnosed with DiGeorge Syndrome, a genetic disorder with very little resource around it.
DiGeorge Syndrome is a congenital disorder caused by deletions in large portions of chromosome 22, resulting in the loss of several genes. The most common characteristic is an absent or nonfunctional thymus. The thymus is involved in producing …read more

The elementary concept is that the father’s role in making babies is to only contribute the sperm, and the mother does all the work. That after fertilization, the development of the resulting embryo is at the mercy of the mother’s egg cytoplasm that received it.
Well, recent studies show that dad’s sperm contains a set of instructions that make certain the embryo develops properly, and specifically that his genes get turned on at the right time.
But let’s do a short tutorial first…
Each chromosome is really just a single long DNA molecule, that can stretch out to an …read more

Consider a hairy, moist armpit is a “rainforest” of bacteria, but the forearm is a desert. Scientists surveyed the types of micro-organism living on a healthy human skin and found that it’s much more diverse and crowded than originally thought.
There’s a common notion that all bacteria on the skin are bad, but that’s not exactly true. Some bacteria are beneficial to us, but what they are and where they thrive on the skin has never been studied before. Enter the “Human Microbiome Project” of the NIH, which was created to find out the roles that bacterial communities play …read more

There are over 40 known diseases that are passed only from mother to child, some of them severe and debilitating. These diseases come from the mitochondrial DNA (mtDNA) of the mother, but the proportion of DNA that is passed to the children are so varied that scientists have no means of predicting the severity and presenting symptoms of the disease in the offsprings.
That is, until recently when scientists located a genetic bottleneck in the mitochondria of the mother’s developing eggs that determines the proportion of mutated mtDNA that mothers transmit to their child. Understanding this bottleneck event, and really …read more

There was one compelling reason why I opted out of genetic testing with my last pregnancy. The risk of miscarriage due to amniocentesis was the same as the risk of having a baby with Down Syndrome.
Amniocentesis is considered the gold standard, but it’s an invasive procedure with a 1/100 risk for miscarriage, the same risk for Downs. I quickly realized I would rather give birth to a baby with Downs than be responsible for a miscarriage.
Fortunately, now there is a new, totally non-invasive procedure for genetic testing of Down Syndrome. It only requires the maternal blood sample (basic blood …read more