Posts tagged with "Genetics"

Tress distress: Why women lose hair

February 17, 2020

Talk about a bad hair day. When a woman realizes that her hair is no longer as thick and lustrous as it used to be—in fact, it has become downright thin in certain spots, or worse yet, overall—it can be a cause for panic.

Most of the time minor hair loss is just a sign that your body is growing new, healthy strands to replace the old, according to a report by Self magazine. In fact, losing up to 100 hairs per day is totally normal.

But, “if all of a sudden you’re noticing a lot more in the brush or the drain, or your ponytail is thinner, or you’re seeing more scalp,” then you may be losing more hair than you should, Francesca Fusco, M.D., dermatologist at Wexler Dermatology in New York City and assistant clinical professor of Dermatology at Mount Sinai Hospital, told the news outlet.

Figuring out why you’re suddenly losing more hair than usual can be tricky. For example, hereditary hair loss (androgenetic alopecia), isn’t really something you can control; you get the hand you’re dealt.

But other types of thinning, such traction alopecia or temporary hair shedding (a very common condition called telogen effluvium), can be managed or even reversed, if caught early. Making things even more complicated, some causes of hair loss in women result in sudden shedding while others may become progressively more noticeable over time.

According to Self, if you’ve noticed your hair is falling out more than usual, looks thinner, or seems to be growing more slowly, one of the following may be the reason:

1. Genetics: When we think of hereditary hair loss, we usually go straight to male pattern baldness. But people of all genders are susceptible to hereditary hair loss. In women the hair loss is usually concentrated at the crown of the head (especially noticeable at the hair part), while it’s more likely to affect men along the hairline, the American Academy of Dermatology notes. Although you can’t prevent this type of hair loss entirely, there are treatments available—such as over-the-counter minoxidil or finasteride (propecia)—that can slow it down and make hair stay fuller longer. So the sooner you start treatment, the better.

2. Childbirth: During pregnancy, most women notice their hair going into rapid growth mode. “That’s when everything is in a grow, grow, grow phase, because there are surges of hormones [estrogen] that make hair grow,” Dr. Fusco notes. Not only is the growth stage kicked into high gear, but also it lasts longer than normal, meaning that normal shedding doesn’t occur. However, once estrogen levels go back to normal after delivery, hair resumes its normal growth cycles and starts to shed all of those extra, luscious strands

This type of hair loss (technically, hair shedding) is called telogen effluvium, and it can occur months after a stressful or major life event like childbirth, Bethanee Schlosser, M.D., assistant professor of Dermatology and director of the Women’s Skin Health Program for Northwestern Medicine, told Self recently. “Shedding peaks about four months after the incident” that caused it, she explains. 

3. Changes in birth control: Going off hormonal birth control or changing to a different type of hormonal contraception can also cause hormone-induced shedding. “Whether you’re just starting it, discontinuing it, or changing brands, your body can react by causing the hair to go into an increased shedding mode,” Dr. Fusco says. This is another form of telogen effluvium, which means that it’s usually temporary. You can rely on volumizing products and styling tricks while you wait for your hair to regain its fullness.

4. Nutritional deficiencies: Creating and maintaining healthy hair relies on getting appropriate nutrition. In particular, deficiencies in iron, zinc, vitamin B3 (niacin), and protein have all been linked to various types of hair loss. Treating a nutritional deficiency usually starts with a chat with your doctor and a blood test to accurately diagnose your issue. Then your doctor may treat your deficiency with prescription supplements or may refer you to a dietitian. for further guidance.

5. Medications: Some “medications can cause chronic shedding,” Dr. Schlosser says. In particular, those used to manage high blood pressure, cancer, arthritis, and depression are known to cause hair loss issues, according to the Mayo Clinic.If you think your medication may be causing hair loss, check in with your doctor. In many cases, this type of hair loss is temporary. But if your hair loss becomes chronic, your doctor may be able to prescribe a different medication that doesn’t cause this side effect.

6. Dandruff or scalp psoriasis: When the skin on the scalp is inflamed and itchy, it’s obviously tempting to scratch it. But that may cause your hair to shed more than usual. Dandruff is the most easily treated cause of hair loss, Dr. Fusco says, because you can treat it with over-the-counter oo and conditioner you like enough to use regularly. But other conditions can also cause itchiness and scalp flaking, including seborrheic dermatitis (a more severe version of dandruff caused by a buildup of yeast and oil) and psoriasis (an autoimmune condition that causes thick patches of skin). If you think you have one of these conditions, check in with a dermatologist, Self advises.

7. Intense emotional or physical stress: When you’re experiencing something stressful or traumatic—not your average day-to-day stress, but something big and life-altering like a divorce, a death in the family, a significant job change, or a big move—you may experience a temporary halt in hair growth as your body puts its efforts into getting you through said big event.

“Hairs don’t all grow at the same rate,” Dr. Schlosser told the news outlet. “Some are growing, some are resting, and some are actively being shed. When you have these conditions, your body halts hair growth, and then things get restarted and all these hairs that have been halted start to get pushed out at the same time.” The same thing can happen with physical stress and trauma, like having a big operation, being hospitalized, or even losing a significant amount of weight very quickly. St

8. Autoimmune diseases: “An autoimmune condition makes the body recognize its own hair follicles as foreign and it attacks them and makes the hair fall out,” Dr. Fusco explains. This could be a condition like alopecia areata, in which the immune system attacks the hair follicles. Sometimes people with alopecia areata do see their hair grow back (although it may fall out again). But if not, dermatologists can help by prescribing various treatments, like corticosteroid injection to stimulate hair growth, the AAD says.

Conditions that primarily affect another part of the body—like thyroid disease, rheumatoid arthritis, or sickle-cell anemia—can also cause hair loss as one of many symptoms. Additionally, Dr. Schlosser notes that lupus can cause some scarring of the hair follicle, resulting in permanent hair loss.If you think your hair loss may be connected to an underlying issue like an autoimmune condition, it’s important to talk to your doctor.

9. Wearing too-tight hairstyles too often: Tight hairstyles can cause traction alopecia, Dr. Schlosser says. “Classically, this happens when people wear tight braids chronically, but I’ve seen it with tight ponytails too,” she explains. It can cause progressive thinning of the hairline, and if you do it for long enough, the hair loss may actually become permanent. It’s considered a scarring process, which can damage the hair follicle beyond repair.

10. Heat-styling your hair regularly: Fusco says that women will come to her and tell her they have hair loss, when really they have something called trichorrhexis nodosa. This is a condition in which damaged, weak points in the hair shaft cause strands to break off easily. The cause? Thermal damage to the hair from things like using hot tools and overbleaching. In this case, the hair loss “is not necessarily from the root but it’s from somewhere along the shaft,” she explains. Treatment for trichorrhexis nodosa usually involves finding and avoiding the source of the damage, which could be hot tools, harsh chemicals, or aggressive brushing. Instead, opt for gentle brushing techniques and gentle, soothing hair products.

11. Overprocessing your hair: Getting frequent perms, chemical straightening procedures, or relaxing procedures—basically anything that uses harsh chemicals on your scalp and hair—can damage the hair follicle and cause permanent hair loss. “After repeated insults, the hair follicles just won’t grow back,” Dr. Schlosser says. This can cause hair to appear thinner, and may be especially noticeable on the scalp. If you want your hair to grow back, you’ll likely need to enlist the guidance of a board-certified dermatologist.

Overall, unless your hair loss is caused by a product or lifestyle change, or a hereditary condition, remember to treat your hair gently, take the proper nutrients, and eliminate harsh products from your daily routines. Your good hair days may outnumber the bad ones sooner than you think.

Research contact: @Selfmagazine

Strong-arm tactics: Bottle feeding is linked to left-handedness

January 11, 2019

Bottle feeding infants is associated with left-handedness, according to findings of a study conducted at the University of Washington and released on January 7.

The study found that the prevalence of left-handedness is lower among breastfed infants, as compared to bottle-fed babies. This finding was identified in about 60,000 mother-infant pairs and accounted for known risk factors for handedness.

The results provide further insight into the development of complex brain functions which ultimately determine which side of the batter box the infant likely will choose.

“We think breastfeeding optimizes the process the brain undergoes when solidifying handedness,” said Philippe Hujoel, the study’s author, a professor at the UW’s School of Dentistry and an adjunct professor of Epidemiology at the School of Public Health. “That’s important because it provides an independent line of evidence that breastfeeding may need to last six to nine months.”

The study does not imply, however, that breastfeeding leads to right-handedness, Hujoel said. Handedness, whether it be right- or left-handed, is set early in fetal life and is at least partially determined by genetics. The research does sheds light on when the region of the brain that controls handedness localizes to one side of the brain, a process known as brain lateralization. Possibly, the research shows, breastfeeding optimizes this lateralization towards becoming right- or left-handed.

According to Scientific American magazine, about 15% of people are left-handed—and males are more than twice as likely to be left-handed as females. How does that match up with statistics for breastfeeding and bottle feeding? Based on data released by the Centers for Disease Control and Prevention , among U.S. children born between the years 2009 and 2015, 10% were exclusively bottle-fed for the first six months of life; while 30% were bottle-fed exclusively up to the age of three months.

The good news, according to Daily Infographic, is that left-handers are more likely to be geniuses and left-handed men are, on average, 15% more affluent than their right-handed peers.

Interestingly enough, statistically, the older a mother is, the more likely she is to give birth to left-handed children. But we don’t know how likely older mothers are to bottle-feed versus breastfeed.

Research contact: @UWMedicine

All in the family? DNA doesn’t determine longevity

November 15, 2018

If most people in your family live to a ripe old age, that might just be luck or coincidence. Findings of a study of the family trees of more than 400 million people indicate that the heritability of life span is well below past estimates.

Indeed, the research—conducted by Calico Life Sciences in cooperation with AncestryDNA—has determined that previous investigations into the role of genetics in longevity have failed to account for our tendency to select partners with similar traits to our own.

The new findings have been published in the November edition of Genetics, a journal of the Genetics Society of America.

“We can potentially learn many things about the biology of aging from human genetics, but if the heritability of life span is low, it tempers our expectations about what types of things we can learn and how easy it will be,” says lead author Graham Ruby of San Francisco-based Calico—a Google-funded research and development company that uses advanced technologies to further understand  the biology that controls lifespan.

Heritability is a measure of how much of the variation in a trait—in this case, life span—can be explained by genetic differences, as opposed to non-genetic differences such as lifestyle, sociocultural factors, and accidents. Previous estimates of human life span heritability have ranged from around 15% to 30%.

Starting from 54 million subscriber-generated public family trees representing 6 billion ancestors, Ancestry removed redundant entries and those from people who were still living, stitching the remaining pedigrees together. Before sharing the data with the Calico research team, Ancestry stripped away all identifiable information from the pedigrees, leaving only the year of birth, year of death, place of birth (to the resolution of state within the US and country outside the US), and familial connections that make up the tree structure itself.

They ended up with a set of pedigrees that included over 400 million people—largely Americans of European descent—each connected to another by either a parent-child or a spouse-spouse relationship. The team was then able to estimate heritability from the tree by examining the similarity of life span between relatives.

Using an approach that combines mathematical and statistical modeling, the researchers focused on relatives who were born across the 19th and early 20th centuries, finding heritability estimates for siblings and first cousins to be roughly the same as previously reported. But, as was also observed in some of the previous studies, they noted that the life span of spouses tended to be correlated: They were more similar, in fact, than in siblings of opposite gender.

This correlation between spouses could be due to the many non-genetic factors that accompany living in the same household—their shared environment. But the story really started to take shape when the authors compared different types of in-laws, some with quite remote relationships.

The first hint that something more than either genetics or shared environment might be at work was the finding that siblings-in-law and first-cousins-in-law had correlated life spans—despite not being blood relatives and not generally sharing households.

The size of their data set allowed the team to zoom in on longevity correlations for other more remote relationship types, including aunts and uncles-in-law, first cousins-once-removed-in-law, and different configurations of co-siblings-in-law. The finding that a person’s sibling’s spouse’s sibling or their spouse’s sibling’s spouse had a similar life span to their own made it clear that something else was at play.

If they don’t share genetic backgrounds and they don’t share households, what best accounts for the similarity in life span between individuals with these relationship types? Going back to their impressive data set, the researchers were able to perform analyses that detected assortative mating.

“What assortative mating means here is that the factors that are important for life span tend to be very similar between mates,” says Ruby. In other words, people tend to select partners with traits like their own—in this case, how long they live.

Of course, you can’t easily guess the longevity of a potential mate. “Generally, people get married before either one of them has died,” jokes Ruby. Because you can’t tell someone’s life span in advance, assortative mating in humans must be based on other characteristics.

The basis of this mate choice could be genetic or sociocultural—or both. For a non-genetic example, if income influences life span, and wealthy people tend to marry other wealthy people, that would lead to correlated longevity. The same would occur for traits more controlled by genetics: If, for example, tall people prefer tall spouses, and height is correlated in some way with how long you live, this would also inflate estimates of life span heritability.

By correcting for these effects of assortative mating, the new analysis found life span heritability is likely no more than 7 percent, perhaps even lower.

The upshot? Choose your mate wisely. How long you live has less to do with your genes than you might think.

Research contact:graham@calicolabs.com