Genetics 101

What are Genes?
Genes are the fundamental units of heredity—they provide the instruction for a particular trait such as hair or eye color. Genes are made up of a chemical called deoxyribonucleic acid, or DNA. Each gene contains the instructions for making a specific protein, and each protein has a particular function in the body, such as manufacturing enzymes for biochemical processes.


What are Chromosomes?
Chromosomes are the structures in which genes are packaged. Chromosomes come in pairs, and there can be hundreds and even thousands of genes on one chromosome. Every cell has a total of 46 chromosomes, each with 23 pairs. Half of your chromosomes come from your mother and other half from your father. The first 22 pairs are referred to as autosomes because they are the same between males and females, but the 23rd and final pair are called sex chromosomes because these determine our biological sex. Males have an X and a Y chromosome while females have two X chromosomes.


What are Genetic Disorders?
These arise when one or both copies of a specific gene have undergone an alteration or mutation. When a mutation in just one of these gene copies is sufficient to cause a disease, that disorder is considered “dominant”. When a mutation in both gene copies is required to cause a disease, that disorder is considered recessiveThis is because the normal gene copy compensates for the defective copy. As a result, most carriers of recessive disorders are healthy individuals with no signs or symptoms of a condition

Autosomal dominant inheritance
In dominant conditions, individuals who possess a mutation are usually affected by a disorder, or they are at an increased risk of developing the disorder. Since each parent only passes one copy of their genes to a child, a child conceived by one parent with the mutation and one parent without the mutation has a 50% chance of inheriting the abnormal copy and the disorder, and a 50% chance of inheriting the normal copy of the gene.

Sometimes a dominant mutation can appear in an individual even if neither parent has the mutation. Such occurrences, referred to as “de novo” mutations, arise when a new mutation occurs in a sperm or egg cell, or in the fertilized egg itself.

Autosomal Recessive Inheritance.
If both copies of the gene carry a mutation, the disorder becomes apparent. In order for an individual to have two mutations in a gene, one must be inherited from each parent. If two carriers of a mutation for the same disorder conceive a child, they have a 25% chance of having a child with the disorder, a 50% chance of having a child who is a carrier, and a 25% of having a child who neither has the disorder nor carries the mutation.

Carriers do not always have a family history with autosomal recessive disorders, because these conditions require both parents to be carriers, and carriers are typically healthy.

X-linked recessive inheritance (sex-linked inheritance):
A gene that is X-linked is located on the X chromosome. Women have two X chromosomes, meaning that in most cases, they have a healthy copy of the gene that can compensate for a mutation in the other copy. Since men have only one X chromosome, they have no such ‘backup’ copy, and tend to be at greater risk for X-linked disorders. However, it is possible for women to be affected by X-linked recessive disorders as well. 

1 in 2 program participants is a carrier of at least 1 of the 83 genetic disorders the Center screens for.

1 in 4 Jews is a carrier for one of 19 "Jewish" genetic disorders, included in the Center's panel of 83. 


We are proud to announce that our Carrier Screening Program is open with our new medical provider Insight Medical Genetics (IMG). Visit our Get Screened page to learn more about our program and how to register!


Do You Know What's In Your Genes?

What is the most valuable gift you can give to your family? The gift of good health! There are many health conditions that run in families. Knowing your family health history can alert you to the potential risk for a variety of genetic disorders . Be sure to check with your relatives for warning signs and assess your risk for hereditary cancers!

Did you know: Ashkenazi Jews are 10 TIMES more likely to have BRCA mutations, which significantly increases lifetime risks for hereditary cancers, so what does this heightened risk mean for you? Click here to learn more !