Gene Therapy for Hemophilia A and Hemophilia B
Mendelian Genetics: Patterns Of Inheritance And Single-Gene Disorders
Autosomal recessive single-gene diseases occur only in individuals with two mutant alleles of the disease-associated gene. Remember, for any given gene, a person inherits one allele from his or her mother and one allele from his or her father. Therefore, individuals with an autosomal recessive single-gene disease inherit one mutant allele of the disease-associated gene from each of their parents. In pedigrees of families with multiple affected generations, autosomal recessive single-gene diseases often show a clear pattern in which the disease "skips" one or more generations.
Phenylketonuria (PKU) is a prominent example of a single-gene disease with an autosomal recessive inheritance pattern. PKU is associated with mutations in the gene that encodes the enzyme phenylalanine hydroxylase (PAH); when a person has these mutations, he or she cannot properly manufacture PAH, so he or she is subsequently unable to break down the amino acid phenylalanine, which is an essential building block of dietary proteins. As a result, individuals with PKU accumulate high levels of phenylalanine in their urine and blood, and this buildup eventually causes mental retardation and behavioral abnormalities.
The PKU-associated enzyme deficiency was determined biochemically in the 1950s—long before the PAH-encoding gene was mapped to human chromosome 12 and cloned in 1983. Specifically, Dr. Willard Centerwall, whose child was mentally handicapped, developed the first diagnostic test for PKU in 1957. Called the "wet diaper" test, Centerwall's test involved adding a drop of ferric chloride to a wet diaper; if the diaper turned green, the infant was diagnosed with PKU. The wet diaper test was used to reliably test infants at eight weeks after birth; by this time, however, infants who were affected by PKU had already often suffered irreversible brain damage.
Thus, in 1960, Dr. Robert Guthrie, whose niece suffered from PKU and whose son was also mentally handicapped, established a more sensitive method for detecting elevated phenylalanine levels in blood, which permitted a diagnosis of PKU within three days after birth. Guthrie's test used bacteria that were unable to make their own phenylalanine as messengers to report high blood levels of phenylalanine in an infant's blood sample obtained via heel prick. With Guthrie's method, the phenylalanine-deficient bacteria were grown in media together with a paper disk spotted with a drop of the infant's blood. If the phenylalanine levels in the blood were high, the bacteria would grow robustly, and a diagnosis of PKU could be made. Through the ability to discover that their child had PKU at such an early age, parents became able to respond immediately by feeding their child a modified diet low in proteins and phenylalanine, thereby allowing more normal cognitive development. Guthrie's test continues to be used today, and the practice of obtaining an infant's blood sample via heel prick is now used in numerous additional diagnostic tests.
Several other human diseases, including cystic fibrosis, sickle-cell anemia, and oculocutaneous albinism, also exhibit an autosomal recessive inheritance pattern. Cystic fibrosis is associated with recessive mutations in the CFTR gene, whereas sickle-cell anemia is associated with recessive mutations in the beta hemoglobin (HBB) gene. Interestingly, although individuals homozygous for the mutant HBB gene suffer from sickle-cell anemia, heterozygous carriers are resistant to malaria. This fact explains the higher frequency of sickle-cell anemia in today's African Americans, who are descendants of a group that had an advantage against endemic malaria if they carried HBB mutations. Finally, oculocutaneous albinism is associated with autosomal recessive mutations in the OCA2 gene. This gene is involved in biosynthesis of the pigment melanin, which gives color to a person's hair, skin, and eyes.
Anxiety Disorders
Anxiety is a normal emotion. It's your brain's way of reacting to stress and alerting you of potential danger ahead.
Everyone feels anxious now and then. For example, you may worry when faced with a problem at work, before taking a test, or before making an important decision.
Occasional anxiety is OK. But anxiety disorders are different. They're a group of mental illnesses that cause constant and overwhelming anxiety and fear. Too much anxiety can make you avoid work, school, family get-togethers, and other social situations that might trigger or worsen your symptoms.
With treatment, many people with anxiety disorders can manage their symptoms.
There are several types of anxiety disorders, including:
Generalized anxiety disorder
You feel excessive, unrealistic worry and tension about typical everyday tasks. These feelings can be constant.
Panic disorder
You feel sudden, intense fear that brings on a panic attack. During a panic attack you may break out in a sweat, have chest pain, and have a pounding heartbeat (palpitations). Sometimes, you may feel like you're choking or having a heart attack. If you have an attack, you might be afraid of having another and might try to avoid certain triggers.
Social anxiety disorder
Also called social phobia, this is when you feel overwhelming worry and self-consciousness about everyday social situations. You obsessively worry about others judging you or being embarrassed or teased. If you have this disorder, you might stay away from social settings.
Phobias
You feel an intense fear of a specific object or situation, such as heights or flying. The fear goes beyond what's appropriate and may cause you to avoid ordinary situations.
Agoraphobia
You have an intense fear of being in a place where it seems hard to escape or get help if an emergency occurs. For example, you may panic or feel anxious when on an airplane, on public transportation, in closed spaces, standing in a line with a crowd, or just being away from your home.
Separation anxiety
Little kids aren't the only ones who feel scared or anxious when a loved one leaves. Anyone can get separation anxiety disorder. If you do, you'll feel very anxious or fearful when a person you're close to leaves your sight. You'll always worry that something bad may happen to your loved one. If you're older, you may have this anxiety after a traumatic event.
Selective mutism
This is a type of social anxiety in which young kids who talk normally with their family don't speak in public, such as at school.
Medication-induced anxiety disorder
If you use certain medications or illegal drugs or withdraw from certain drugs, you may experience some symptoms of anxiety disorder.
Unspecified and other specified anxiety disorders
With these conditions, your anxiety may not fit into any other category but is significant enough to cause stress and other symptoms.
Too much anxiety can make you avoid work, school, family get-togethers, and other social situations that might trigger or worsen your symptoms. With treatment, many people with anxiety disorders can manage their symptoms. (Photo Credit: AJPhoto/Science Source)
The main symptom of anxiety disorders is excessive fear or worry. Anxiety disorders can also make it hard to breathe, sleep, stay still, and concentrate. Your specific symptoms depend on the type of anxiety disorder you have.
Common symptoms are:
There isn't a complete understanding of where anxiety disorders come from. Some causes of anxiety disorders include:
Genetics. Anxiety disorders can run in families.
Brain chemistry. Some research suggests anxiety disorders may be linked to faulty circuits in the brain that control fear and emotions.
Environmental stress. This refers to stressful events you have seen or lived through. Life events often linked to anxiety disorders include childhood abuse and neglect, the death of a loved one, or being attacked or seeing violence.
Drug or alcohol withdrawal or misuse. Certain drugs may be used to hide or decrease certain anxiety symptoms. Anxiety disorder often goes hand in hand with alcohol and substance use.
Medical conditions. Some heart, lung, and thyroid conditions can cause symptoms similar to anxiety disorders or make anxiety symptoms worse. GI disorders (such as irritable bowel syndrome), respiratory conditions (such as asthma), and tumors that create certain hormones can be linked to anxiety.
It's important to get a full physical exam to rule out other medical conditions when talking to your doctor about anxiety. Also, anxiety symptoms can be a first signal of a medical condition.
Certain medications. Withdrawal from certain medications, such as anti-anxiety drugs, can cause anxiety symptoms.
Some things make you more likely to develop an anxiety disorder. These are called risk factors. Some risk factors you can't change, but others you can.
Risk factors for anxiety disorders include:
Mental health conditions. If you have certain mental health conditions, such as depression, it raises your risk for anxiety disorder.
Childhood sexual abuse. Emotional, physical, and sexual abuse or neglect during childhood is linked to anxiety disorders later in life.
Trauma. Living through a traumatic event raises the risk of posttraumatic stress disorder (PTSD), which can cause panic attacks.
Negative life events. Stressful or negative life events, such as losing a parent in early childhood, increase your risk for anxiety disorder. Experiencing more than one smaller stressful event can also put you at risk.
Severe illness or chronic health condition. Constant worry about your health or the health of a loved one, or caring for someone who is sick, can cause you to feel overwhelmed and anxious.
Substance abuse. The use of alcohol and illegal drugs makes you more likely to get an anxiety disorder. Some people also use these substances to hide or ease anxiety symptoms.
Being shy as a child. Shyness and withdrawal from unfamiliar people and places during childhood can be linked to social anxiety in teens and adults.
Low self-esteem. Negative perceptions about yourself may lead to social anxiety disorder.
Family history. Anxiety can be a genetic condition.
If you have symptoms, your doctor will examine you and ask questions about your medical history.
Anxiety disorder test
They may run tests to rule out other health conditions that might be causing your symptoms. No lab tests can specifically diagnose anxiety disorders.
If your doctor doesn't find any physical reason for how you're feeling, they may send you to a psychiatrist, psychologist, or another mental health specialist. Those doctors will ask you questions and use tools and testing to find out if you may have an anxiety disorder.
Your doctors will consider how long you've had symptoms and how intense they are when diagnosing you. It's important to let your doctors or counselors know if your anxiety makes it hard to enjoy or complete everyday tasks at home, work, or school.
The United States Preventive Service Task Force recommends screening for anxiety in children and adolescents ages 8-18 years and screening for major depressive disorder (MDD) in adolescents ages 12-18 years.
There are many treatments to reduce and manage symptoms of anxiety disorder. Usually, people with anxiety disorder take medicine and go to counseling.
Anxiety medication
Several types of drugs are used to treat anxiety disorders. Talk to your doctor or psychiatrist about the pros and cons of each medicine to decide which one is best for you.
Therapies for anxiety
Psychotherapy. This is a type of counseling that helps you learn how your emotions affect your behaviors. It's sometimes called psychological counseling or talk therapy. A trained mental health specialist listens and talks to you about your thoughts and feelings and suggests ways to understand and manage them and your anxiety disorder.
Cognitive behavioral therapy (CBT). A common type of psychotherapy , it teaches you how to turn negative, or panic-causing, thoughts and behaviors into positive ones. You'll learn ways to carefully approach and manage fearful or worrisome situations without anxiety, which is known as exposure therapy. Some places offer family CBT sessions.
These tips may help you control or lessen your symptoms:
Learn about your disorder. The more you know, the better prepared you will be to manage symptoms and problems along the way. Don't be afraid to ask your doctor any questions you might have. Remember, you are a key part of your health care team.
Stick to your treatment plan. Suddenly stopping your meds can cause unpleasant side effects and even trigger anxiety symptoms.
Cut down on caffeine. Avoid foods and drinks containing caffeine, such as coffee, tea, cola, energy drinks, and chocolate. Caffeine is a mood-altering drug, and it may make symptoms of anxiety disorders worse.
Don't use alcohol and recreational street drugs. Substance abuse increases your risk of anxiety disorders.
Eat right and exercise. Brisk aerobic exercises, such as jogging and biking, help release brain chemicals that cut stress and improve your mood.
Get better sleep. Sleep problems and anxiety disorder often go hand in hand. Make getting good rest a priority. Follow a relaxing bedtime routine. Talk to your doctor if you still have trouble sleeping.
Learn to relax. Stress management is an important part of your anxiety disorder treatment plan. Things like meditation or mindfulness can help you unwind after a stressful day and may make your treatment work better.
Keep a journal. Writing down your thoughts before the day is done may help you relax so you're not tossing and turning with anxious thoughts all night.
Manage your negative thoughts. Thinking positive thoughts instead of worrisome ones can help reduce anxiety. This can be challenging if you have certain types of anxiety, however. Cognitive behavioral therapy can teach you how to redirect your thoughts.
Get together with friends. Whether it's in person, on the phone, or on the computer, social connections help people thrive and stay healthy. People who have a close group of friends that support and chat with them have lower levels of social anxiety.
Seek support. Some people find it helpful and uplifting to talk to others who are experiencing the same symptoms and emotions. Self-help or support groups let you share your concerns and achievements with others who are or who have been there.
Ask your doctor. Talk to your doctor or pharmacist before taking any over-the-counter meds or herbal remedies. Many have chemicals that can make anxiety symptoms worse.
It can be challenging and frustrating to live with an anxiety disorder. The constant worry and fear can make you feel tired and scared. If you've talked to a doctor about your symptoms, you've taken the first step toward letting go of the worry.
It can take some time to find the right treatment that works for you. If you have more than one anxiety disorder, you may need several kinds of treatment. For most people with anxiety disorders, a combination of medication and counseling is best. With proper care and treatment, you can learn how to manage your symptoms and thrive.
Feeling anxious from time to time is common. But you may have an anxiety disorder if you often have symptoms, such as nervousness, being unable to stay calm, a fast heartbeat, and having trouble controlling how much you worry. Many treatment options, including behavioral therapy and medication, are available. Talk to your doctor if you think you are having symptoms. They can help you with the proper treatment plan.
What is the 3-3-3 rule for anxiety?
The 3 3 3 rule is a way you can become more grounded when you approach a situation that makes you anxious. If you remind yourself to think about three things you see, three things you hear, and moving three different body parts, you may be able to refocus.
What are the 7 different types of anxiety?
There are several types of anxiety disorders, including general anxiety disorder, phobias, agoraphobia, social anxiety disorder, separation anxiety, panic disorder, and selective mutism.
What is life like for a person with anxiety disorder?
If you have anxiety, you may have frequent moments of worry or fear. You might have physical symptoms such as a rapid heartbeat, dizziness, or feeling weak. You may also avoid certain situations that trigger your symptoms.
How do you deal with anxiety disorder?
Talk to your doctor if you have symptoms of anxiety. You can also learn more about what causes your symptoms and about your specific type of anxiety, join support groups, limit your caffeine intake, and seek ways to manage your stress.
Genetics Studies Have A Diversity Problem That Researchers Struggle To Fix
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