Basic Genetics

DNA and Genes

• DNA (Deoxyribonucleic Acid) is the molecule that carries genetic information.
• DNA is made up of units called nucleotides (A, T, C, G).
• Genes are specific sequences of DNA that code for proteins or functional RNA (Ribonucleic Acid)
• Humans have around 20,000–25,000 genes.

Chromosomes

• DNA is organized into structures called chromosomes.
• Humans have 46 chromosomes (23 pairs). One set comes from the mother, the other from the father.
• The 23rd pair determines biological sex: XX (female) or XY (male).
• A karyotype is an individual's complete set of chromosomes. A specialized laboratory test can produce an image of the chromosomes arranged in a standard order.

Alleles

• A gene can have different versions called alleles.
• For example, a gene for eye color may have a blue allele and a brown allele. Alleles can be "dominant" or "recessive" (explained below).

Genotype and Phenotype

• Genotype: A person's genetic makeup, or the specific set of genes he/she carries.
• Phenotype: The observable traits of an individual, such as eye color, height, behavioral traits, and the presence of genetic diseases.

Dominant and Recessive Traits

• Dominant alleles show their effect even if only one copy is present.
• Recessive alleles need two copies to be expressed.
• Example: If B = brown eyes and b = blue eyes, a person with Bb will have brown eyes.

Genetics and Reproductive Medicine

Some genetic conditions can affect your ability to conceive or carry a healthy pregnancy. Others may increase the risk of passing on a genetic disorder to your child. Reproductive medicine uses genetic testing and counseling to look for these risks and help you make informed decisions.

Fertility Evaluation

Genetic testing can help explain certain causes of infertility, such as inherited conditions or chromosome changes.

Carrier Screening

You and your partner can be tested to see if you "carry" genes for certain inherited conditions (like cystic fibrosis or Tay-Sachs). Even if you're healthy, you could still pass on a condition to your child if both partners are carriers of the same disorder.

Preimplantation Genetic Testing (PGT)

If you're using IVF (in vitro fertilization), embryos can be tested for genetic conditions before they are implanted, helping improve the chances of a healthy pregnancy. Doctors can help couples make informed decisions, such as use of donor eggs and/or sperm if one partner carries a genetic condition.

Pregnancy Planning

Genetic counseling can help you understand your family history and make choices about timing, testing, and treatment.

Personalized Treatment Plans

Genetics can influence how an individual responds to fertility medications. This information can help tailor hormonal treatments and improve success rates of assisted reproduction.

When it comes to fertility, both men and women can be affected by genetic factors that interfere with the ability to conceive or carry a pregnancy. Here are a few examples of how genetics can play a role in infertility:

In Women:

• Chromosomal issues like Turner syndrome (missing or incomplete X chromosome) can affect ovarian function.
• Gene mutations may impact hormone levels, egg quality, or ovulation.
• Conditions like Fragile X syndrome can cause premature ovarian failure.

In Men:

• Y-chromosome microdeletions (missing pieces of the Y chromosome) can lead to low or absent sperm production.
• Klinefelter syndrome (extra X chromosome) often results in reduced testosterone and sperm production.
• CFTR gene mutations (associated with cystic fibrosis) can cause the absence of the vas deferens, which carries sperm.

In Couples:

• Recurrent miscarriage or failed IVF cycles may sometimes be due to chromosomal translocations or inherited mutations in one or both partners.

Working with a Genetic Counselor

A genetic counselor is a healthcare professional who helps individuals and families understand and make informed decisions about genetic conditions. Their primary functions include:

Risk Assessment

Evaluate personal and family medical histories to determine the likelihood of a genetic condition. Assess the risk of inherited disorders or birth defects.

Education and Information

Explain complex genetic concepts in understandable terms. Provide information about specific genetic conditions, inheritance patterns, testing options, and available treatments.

Genetic Testing Coordination

Recommend appropriate genetic tests and help interpret the results. Guide patients through the testing process, including potential outcomes and implications.

Emotional Support and Counseling

Help individuals cope with the psychological and emotional aspects of genetic conditions or test results. Support decision-making related to family planning, treatment options, or preventive measures.

Ethical and Confidential Guidance

Assist patients in making choices that align with their values and beliefs. Ensure patient confidentiality and informed consent throughout the process.

It's Normal to Feel Overwhelmed

Genetics can sound complex, especially when you're already dealing with the emotional weight of infertility. But you're not alone—many couples facing infertility find answers through genetic testing and counseling. The entire EIS clinical team is available to help you navigate these issues, answer your questions, and plan your personalized care.