Genes and genetics explained

Genes and Genetics Explained in Grand Rapids, Michigan

Our bodies are built from a detailed biological “blueprint” stored in our genes. For people living in Grand Rapids, MI, understanding genes and genetics can help you make informed decisions about your health, your family, and when to seek local genetic services at places like Corewell Health (formerly Spectrum Health), Trinity Health Grand Rapids, and University of Michigan Health-West (formerly Metro Health).

What Are Genes, DNA, and Chromosomes?

Inside almost every cell in your body is a control center called the nucleus. In that nucleus are chromosomes—long strands of a chemical called deoxyribonucleic acid (DNA).

DNA looks like a twisted ladder (a “double helix”). Along each side of the ladder are “letters” (A, T, C, and G). Specific sequences of these letters form genes.

• Chromosomes: Humans usually have 46 chromosomes in each cell (23 pairs).
  • 22 pairs are called autosomes (non-sex chromosomes).
  • 1 pair are sex chromosomes (XX or XY).
• Genes: Each person has between 20,000 and 25,000 genes.
• DNA: The molecule that carries all genetic instructions.

In Grand Rapids, genetic testing done at major health systems reads these DNA “letters” to look for changes that may affect health.

How Genes Work: Your Body’s Instruction Book

Each gene is like a specific instruction in a very large instruction manual. These instructions tell your cells how to make important molecules such as:

• Proteins – build and repair tissues, run chemical reactions
• Hormones – help control growth, metabolism, mood, and more

Although nearly every cell has two copies of each gene, only the genes needed for that cell’s job are “switched on.” Others are “switched off.”

For example:

• A muscle cell switches on genes needed for contraction.
• A skin cell switches on genes needed for protection and pigment.

This precise control helps your body function normally, whether you’re walking along the Grand River in summer or fighting off a winter infection during a cold West Michigan January.

When Genes Change: Mutations and Variants

Sometimes a gene contains a change (also called a mutation or variant) that alters its instructions. These changes can:

• Happen spontaneously (with no known cause), or
• Be inherited from one or both parents.

Depending on where the change occurs and how important that gene is, the result can range from:

• No noticeable effect
• Mild differences (such as a trait like eye color)
• A health condition present at birth or later in life

Scientists estimate that more than 10,000 conditions are caused by changes in single genes.

How We Inherit Chromosomes and Sex

Two Copies of Each Chromosome

People usually have two copies of each chromosome:

• One copy from the mother’s egg
• One copy from the father’s sperm

Egg and sperm cells each contain 23 chromosomes. When the sperm fertilizes the egg:

• The 23 chromosomes from each parent combine
• The embryo now has 46 chromosomes (23 pairs)
• This means two copies of each gene—one from each parent

Sex Chromosomes: X and Y

The chromosomes that determine biological sex are called sex chromosomes:

• Eggs always contribute an X chromosome.
• Sperm contribute either an X or a Y chromosome.

Typical combinations are:

• XX – biologically female
• XY – biologically male

Sex chromosomes do more than determine sex. They also carry genes that affect other body functions. There are:

• Many genes on the X chromosome

• Fewer genes on the Y chromosome

• Genes on the X chromosome are called X‑linked.

• Genes on the Y chromosome are called Y‑linked.

Traits, Alleles, and Genetic Variation

Parents pass on traits—such as eye color, hair color, and blood type—through their genes.

Each gene can come in different forms called alleles (pronounced “AL‑eel”). For example, the gene for blood type has several alleles:

• A
• B
• O

Your two copies of a gene (one from each parent) form your genotype. How that genotype shows up in your body (for example, your actual blood type) is called your phenotype.

Dominant and Recessive Genes

The most common interaction between alleles is a dominant/recessive relationship:

• A dominant allele: its effect shows even if only one copy is present.
• A recessive allele: its effect shows only if both copies are recessive.

Eye Color Example

• Let B = brown eye allele (dominant)
• Let b = blue eye allele (recessive)

Possible combinations:

• BB – brown eyes
• Bb – brown eyes (brown dominates over blue)
• bb – blue eyes (no dominant brown allele present)

Blood Group Example (A and O)

Blood group alleles: A, B, O

• The A allele is dominant over O.
• The O allele is recessive.

If:

• Mother has alleles A and O (AO) – blood group A
• Father has alleles O and O (OO) – blood group O

Each child has:

• 50% chance of inheriting AO → blood group A
• 50% chance of inheriting OO → blood group O

In this example:

• Genotype could be AO or OO
• Phenotype is blood group A (AO) or blood group O (OO)

Carriers and Recessive Genetic Conditions

Sometimes a person has:

• One unchanged (working) copy of a gene (often written as Q)
• One changed (non‑working) copy of a gene (often written as q)

If they do not have the condition, they are called a carrier. The condition is said to follow a recessive inheritance pattern.

If both parents are carriers (Qq and Qq), then for each pregnancy:

• 25% (1 in 4) chance the child gets QQ (unaffected, not a carrier)
• 50% (1 in 2) chance the child gets Qq (unaffected carrier)
• 25% (1 in 4) chance the child gets qq (affected, has the condition)

Recessive conditions are more likely if the parents are related (share ancestors), but these conditions are still relatively rare.

Examples of autosomal recessive conditions include:

• Cystic fibrosis
• Phenylketonuria (PKU)

In Grand Rapids, newborns are routinely screened for conditions like PKU through Michigan’s newborn screening program, coordinated with the Kent County Health Department.

Co‑Dominant Genes

Not all genes are strictly dominant or recessive. In some cases, both alleles are equally strong. This is called co‑dominance.

Blood Group Example (A and B)

For the blood group gene:

• A and B are co‑dominant.
• O is recessive.

If a person has:

• One A allele and one B allele (AB), both are expressed.
• Their blood group is AB (not A or B alone).

If:

• One parent has blood group B (BO)
• The other has blood group A (AO)

Each child has:

• 25% chance of blood group AB (AB)
• 25% chance of blood group A (AO)
• 25% chance of blood group B (BO)
• 25% chance of blood group O (OO)

Gene Changes in Cells: Somatic vs Germ Cells

Cells reproduce by copying their genetic information and then splitting into two cells. Sometimes, during this process, a genetic change occurs.

There are two main types of cells to consider:

• Germ cells – sperm and egg cells
• Somatic cells – all other body cells (skin, lung, liver, etc.)

Changes in Somatic Cells

If a genetic change happens in somatic cells:

• It can cause a disease in that person.
• It will not be passed to their children.

Example:

• Skin cancer can be caused by a buildup of gene changes in skin cells due to:
  • UV radiation from the sun (a concern even in Michigan summers, especially around Lake Michigan and outdoor activities)
  • Exposure to certain chemicals
  • Cigarette smoke

Changes in Germ Cells

If a genetic change happens in germ cells (egg or sperm):

• It can be passed on to children.
• The child may inherit the altered gene and may be at risk for a genetic condition.

How Genetic Conditions Arise

Genetic conditions can arise in several ways:

1. A changed gene is passed from parent to child

   • Can cause health issues at birth or later in life.

2. A gene change occurs spontaneously

   • Happens during the formation of egg or sperm, or at conception.
   • There may be no family history.

3. Genetic susceptibility plus environment

   • A person may inherit a susceptibility (increased risk) to a condition.
   • Environmental triggers—such as diet, smoking, certain chemicals, or UV exposure—can increase the chance that the condition will develop.

Having a genetic susceptibility does not mean you will definitely develop the condition. If triggers are avoided, the condition may never appear.

In Michigan, examples often discussed include:

• Certain cancers (some breast, colon, and skin cancers)
• Conditions influenced by diet and lifestyle, such as heart disease and type 2 diabetes

Environment, Lifestyle, and Genetics in West Michigan

Living in Grand Rapids and the broader West Michigan region means dealing with:

• Cold, long winters – more time indoors, higher risk of low vitamin D, seasonal affective disorder, and respiratory infections.
• Warm, sunny summers – higher UV exposure during outdoor activities along the Grand River, at Lake Michigan beaches, and local parks.

Your genes may influence how your body responds to:

• Sun exposure (risk of skin cancer)
• Diet and weight (risk of heart disease, high cholesterol, and diabetes)
• Immune response (how you fight infections)

By understanding your genetic risks and making healthy lifestyle choices, you can help reduce your overall risk. This is a common focus in preventive care at clinics across Grand Rapids, including Corewell Health and Trinity Health Grand Rapids.

Related Parents and Genetic Risk

Parents who are related (for example, cousins) share more of the same genetic material. This increases the chance that both parents carry the same recessive gene change.

If both partners carry the same recessive gene change:

• Their children are more likely to inherit that condition.

Related couples are encouraged to seek genetic counseling—especially if there is a known family history of a genetic condition.

Genetic Counseling and Testing in Grand Rapids, MI

If a family member has been diagnosed with a genetic condition, or you know that a condition runs in your family, speaking with a genetic counselor can be very helpful.

What Genetic Counselors Do

Genetic counselors are health professionals trained in both genetics and counseling. They:

• Explain what a genetic condition is and what causes it.
• Describe how it is inherited (if it is).
• Discuss what a diagnosis means for you and your family.
• Help you understand your options for:
  • Genetic testing
  • Family planning
  • Screening and prevention
• Provide emotional support and connect you with local and online support groups.

They are trained to be sensitive to your:

• Family situation
• Culture
• Beliefs and values

Local Genetic Services in the Grand Rapids Area

In and around Grand Rapids, genetic services may be available through:

• Corewell Health / Corewell Health – Grand Rapids
  Genetic counseling and testing services for children, adults, and families.

• Trinity Health Grand Rapids
  Clinical genetics and cancer risk assessment services.

• University of Michigan Health-West
  Specialty clinics that can refer for genetics evaluation.

• Trinity Health Grand Rapids (now part of Trinity Health)
  Access to regional genetics and high‑risk clinics.

• Kent County Health Department & Grand Rapids Public Health resources
  Information on newborn screening, family health programs, and referrals.

Always start by talking with:

• Your primary care doctor or primary care doctor
• Your child’s pediatrician
• A specialist (such as an oncologist or cardiologist) if you already have a diagnosis

They can refer you to appropriate genetic services in West Michigan.

For genetic counseling in Grand Rapids, ask your primary care doctor for a referral:

• Medical genetics programs at Corewell Health and University of Michigan Health-West offer genetic counseling (ask your primary care doctor for a referral).
• Find a certified genetic counselor through the National Society of Genetic Counselors at findageneticcounselor.com.

Key Points About Genes and Genetics

• A change in a gene can occur spontaneously (no known cause) or can be inherited.
• Variations (alleles) in a gene cause different forms of a trait (for example, blood type A, B, AB, or O).
• The most common interaction between alleles is a dominant/recessive relationship.
• If a mother has blood group alleles A and O (AO), her blood group will be A because the A allele is dominant.
• Spontaneous genetic changes can affect how the body functions; if they occur in germ cells, they can be passed to children.
• About half of people will experience a condition in their lifetime that is at least partly genetic in origin.
• Avoiding environmental triggers (such as smoking, excess sun exposure, and unhealthy diet) can significantly reduce the risk of some genetically influenced conditions.

When to Seek Help in Grand Rapids

Consider talking to your doctor or a genetic counselor if:

• You or your child has a known genetic condition.
• Several family members have the same or related health problems, especially at a young age (for example, breast cancer, colon cancer, heart disease, or sudden cardiac death).
• You are planning a pregnancy and:
  • Have a family history of a genetic condition.
  • Are related to your partner.
• You are concerned about how your genes and lifestyle (diet, smoking, sun exposure, etc.) might interact to affect your health.

Early information and guidance—from your Grand Rapids healthcare provider and local genetic services—can help you make informed decisions and manage your health more confidently.