A Parent’s Guide to
Sickle Cell Trait
Compiled by: New England Newborn Screening Program and Boston Medical Center
Supported by: HRSA grant U38 MC22215-01-00
Revised 2012
Sickle Cell Trait
What You Should Know
 Sickle Cell Trait is inherited from a parent
 Sickle Cell Trait will NOT turn into Sickle Cell Disease
 Approximately 1 out of 10 African Americans have Sickle Cell Trait
 Approximately 1 in 40 Latinos have Sickle Cell Trait
 Sickle Cell Trait is found among all races especially persons of African, Caribbean, South
and Central American, Greek, Turkish, Italian, Arab, and Asiatic Indian origin
 If a baby has Sickle Cell Trait, then one or both parents have Sickle Cell Trait
 If both parents have Sickle Cell Trait, then there is a 1 in 4 chance that a child may inherit
the genes for Sickle Cell Disease
 Parents should have a blood test to see if they have Sickle Cell Trait
 Please talk to your child’s doctor or to a Hematologist (blood doctor) to discuss what it
means to have Sickle Cell Trait
Source: New England Newborn Screening Program
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Red Blood Cells & Hemoglobin
Red blood cells are found in our blood and contain hemoglobin. Hemoglobin carries oxygen
throughout our body. Most people’s red blood cells contain hemoglobin A.
This is a red blood cell from a person
with normal hemoglobin A.
This is a red blood cell from a person
with Sickle Cell Trait. It contains both
hemoglobin A and hemoglobin S,
but it is also a healthy normal cell.
Parents and family members can have
a simple blood test to determine if they
have Sickle Cell Trait.
This is a red blood cell from a person
with Sickle Cell Disease. It contains
only hemoglobin S. The red blood
cells of a person with Sickle Cell Disease
can lose their round shape and change
to a sickle or crescent. The sickled red
blood cell does not work like a normal
red blood cell. Red blood cells can also
contain Hemoglobin F, which may help
to reduce the chance of sickling.
Source: New England Newborn Screening Program
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Genes, Heredity & Hemoglobin
Genes determine eye color, height, skin color and our hemoglobin type. Heredity is the
passing of genes from parent to child. Everyone has 2 genes for hemoglobin, one from our
mother and one from our father.
Hemoglobin possibilities for a pregnancy:
Source: New England Newborn Screening Program
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What You Should Know About Sickle Cell Trait
What Is Sickle Cell Trait?
Sickle cell trait (SCT) is not a disease, but having it means that a person has
inherited the sickle cell gene from one of his or her parents. People with SCT
usually do not have any of the symptoms of sickle cell disease (SCD) and live a
normal life.
What Is Sickle Cell Disease?
SCD is a genetic condition that is present at birth. In SCD, the red blood cells
become hard and sticky and look like a C-shaped farm tool called a “sickle.” The
sickle cells die early, which causes a constant shortage of red blood cells. Also,
when they travel through small blood vessels, they get stuck and clog the blood
flow. This can cause pain and other serious problems. It is inherited when a child
receives two sickle cell genes—one from each parent. A person with SCD can
pass the disease or SCT on to his or her children.
How Does Someone Get Sickle Cell Trait?
People who have inherited one sickle cell gene and one normal gene have SCT.
This means the person won’t have the disease, but will be a trait “carrier” and can
pass it on to his or her children.
Who Is Affected By Sickle Cell Trait?
SCT affects 1 in 12 Blacks or African Americans in the United States.
•• SCT is most common among Blacks or African Americans, but can be found
among people whose ancestors come from sub-Saharan Africa; the Western
Hemisphere (South America, the Caribbean, and Central America); Saudi
Arabia; India; and Mediterranean countries such as Turkey, Greece, and Italy.
•• Approximately 3 million people living in the United States have SCT and
many are unaware of their status.
What Are The Chances That A Baby Will Have Sickle Cell Trait
•• If both parents have SCT, there is a 50% (or 1 in 2) chance
that the child also will have SCT if the child inherits the
sickle cell gene from one of the parents. Such children
will not have symptoms of SCD, but they can pass SCT on
to their children.
•• If both parents have SCT, there is a 25% (or 1 in 4) chance
that the child will have SCD.
•• There is the same 25% (or 1 in 4) chance that the child
will not have SCD or SCT.
•• If one parent has SCT, there is a 50% (or 1 in 2) chance
that the child will have SCT and an equal 50% chance
that the child will not have SCT.
National Center on Birth Defects and Developmental Disorders
Division of Blood Disorders
CS216728
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What Health Complications Are Associated
With Sickle Cell Trait?
Most people with SCT do not have any symptoms of SCD, although
— in rare cases — people with SCT might experience complications
of SCD, such as “pain crises” and, in extreme circumstances, sudden
death. More research is needed to find out why some people with
SCT have complications and others do not.
In their extreme form and in rare cases, the following conditions
could be harmful for people with SCT:
•• Increased pressure in the atmosphere (e.g., while scuba diving).
•• Low oxygen levels in the air (e.g., when mountain climbing,
exercising extremely hard in military boot camp, or training for
an athletic competition).
•• Dehydration (e.g., too little water in the body).
•• High altitudes (e.g., flying, mountain climbing, or visiting a city at
a high altitude).
How Will A Person Know If He Or She Has
Sickle Cell Trait?
A simple blood test can be done to find out if someone has SCT.
•• Testing is available at most hospitals or medical centers,
from SCD community-based organizations, or at local health
departments.
•• A small sample of blood is taken from the finger (a “needle
prick”) and evaluated in a laboratory.
•• If the results of the test reveal that someone has SCT, it is
important that he or she know what SCT is, how it can affect
him or her, and if and how SCD runs in his or her family.
The best way to find out if and how SCD runs in a person’s family is
for the person to see a genetic counselor. These professionals have
experience with genetic blood disorders. The genetic counselor
will look at the person’s family history and discuss with him or
her what is known about SCD in the person’s family. It is best for
a person with SCD to learn all he or she can about this disease
before deciding to have children.
For more information visit: www.cdc.gov/sicklecell
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All You Wanted to Know
About
Sickle Cell Trait
Source: California Department of Public Health; http://www.cdph.ca.gov
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different; in other words, you are
an individual!
Aside from some minor exceptions
that we will explain, sickle cell trait
is not harmful to one’s physical or
emotional health.
In fact, you would have never
found out about your sickle cell
trait, unless you had this special
blood test. Now let us talk in some
more detail about the trait.
Normal red blood cells
Introduction: So, you have just learned that you,
or someone you know, has sickle cell
trait.
Many things must be going through
your mind. What does it mean, and
does it make me different from other
people? Is it dangerous?
Having sickle cell trait simply means
that your red blood cells contain a
different type of hemoglobin (a
component of the red blood cell) in
addition to the common type.
Having this trait does not make you
any more different from other people
than you already are; you are taller or
shorter than some people you know;
the shape of your nose and ear is
What is sickle cell trait? As we said earlier, sickle cell trait
means having a different
hemoglobin, in addition to the
most common type of
hemoglobin. Hemoglobin is the
component of our red blood cells
that gives our blood its red color,
and carries oxygen from the lungs
to all other parts of the body.
Most people have only hemoglobin
A. In contrast, people with sickle
cell trait have both hemoglobin A
and hemoglobin S.
Hemoglobin S is very similar to
hemoglobin A except for one
change in its structure. There are
many other types of hemoglobin
that are also different from the
common type. Examples include
hemoglobins C, D, and E.
Source: California Department of Public Health; http://www.cdph.ca.gov
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How does one get sickle cell trait? Hemoglobin types are inherited
like eye and hair color. Individuals
with sickle cell trait have inherited
the trait from one of their parents.
Is it true that only people of African
ancestry have sickle cell trait? No, it is not. Sickle cell trait occurs
in about one out of ten African
Americans. In addition, this trait is
found among people with ancestors
from the Mediterranean area,
Mexico, and Central and South
America.
Sickle cell trait originated
thousands of years ago in areas
of the world that had malaria.
Areas of the
world where
sickle
hemoglobin
or its variants
are found
North
America
Interestingly, people with sickle cell
trait were more resistant to malaria
and were better able to adapt to
their environment.
Certain genetic conditions are
more likely to occur in some
populations than in others. For
example, “thalassemia” is a blood
condition that is common in Asian
and Mediterranean populations.
Does sickle cell trait lead to any
health problems?
Sickle cell trait rarely causes any
medical problems. Two exceptions
should be mentioned, although
they are uncommon. An individual
with sickle cell trait may experience
Europe
Asia
Africa
South
America
Australia
Source: California Department of Public Health; http://www.cdph.ca.gov
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“Sickled” red blood cells
a painful episode when exposed to
low oxygen pressure.
This may happen, for example,
when going to very high altitudes
(greater than 10,000 feet) or flying
in an unpressurized aircraft.
Another exception involves the
kidney. Individuals with sickle cell
trait may occasionally have
hematuria, which means
microscopic amounts of blood
in the urine. This condition is
generally harmless.
What is sickle cell disease? When an individual has only
hemoglobin S and no hemoglobin
A, then he or she has sickle cell
disease. When red blood cells
containing hemoglobin S release
their oxygen to the tissues, they
change shape from round to sickled
(see illustration). This impairs their
passage through the small blood
vessels.
Since red blood cells are very
important for oxygen delivery
throughout the body, sickle cell
disease can affect many organs as
well as growth and development.
Sickle cell disease may be a severe
disease. Although it cannot be
cured, effective treatment is
available for persons with sickle cell
disease.
Can sickle cell trait develop into
sickle cell disease? No! Sickle cell trait is not a disease.
Individuals with sickle cell trait will
never develop the disease.
Source: California Department of Public Health; http://www.cdph.ca.gov
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Diagram I
When only one of the parents has a
hemoglobin trait:
Sickle Cell Trait
(AS)
Sickle Cell Trait
(AS)
Sickle Cell Trait
(AS)
No Trait
(AA)
partner. Just like hair and eye color,
your child will inherit his or her
hemoglobin pattern from both of
you. That is why both you and your
partner should be tested.
If your partner does not have a
hemoglobin trait, then none of your
children will have sickle cell disease.
With each pregnancy, you will have
a 50% chance of having a child with
sickle cell trait just like you.
(See Diagram I)
If your partner also has a
hemoglobin trait, then the possible
outcomes with each pregnancy
depend on the specific trait he or
she has. If your partner has sickle
cell trait, there are three possible
pregnancy outcomes:
1. A 25 percent chance for a child
without any hemoglobin trait.
No Trait
(AA)
No Trait
(AA)
On the other hand, persons with
sickle cell trait will never “outgrow”
the trait.
If I have sickle cell trait, can my
child have sickle cell disease?
The genetic makeup of your child
comes equally from you and your
2. A 50 percent chance for a child
with sickle cell trait.
3. A 25 percent chance for a child
with sickle cell disease.
(See Diagram II)
So, both you and your partner must
be tested to find out if there is a
chance of having a baby with sickle
cell disease.
Source: California Department of Public Health; http://www.cdph.ca.gov
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Diagram II
When both parents have a
hemoglobin trait:
Sickle Cell Disease
(SS)
Sickle Cell Trait
(AS)
Sickle Cell Trait
(AS)
To discuss these issues, you will
need to contact a genetic counselor
and ask for a counseling
appointment. Counseling will
provide you with important new
information about hemoglobin
traits and diseases and reproductive
issues.
For more information about sickle
cell trait or disease, contact:
Sickle Cell Trait
(AS)
Sickle Cell Trait
(AS)
If the results are normal, the parents
can be reassured. If the results show
that the baby will be affected, the
parents can be better prepared and
they can make informed decisions
regarding the pregnancy.
No Trait
(AA)
What shall I do if my partner has
a hemoglobin trait as well?
If both you and your partner have
a hemoglobin trait, then there are
several options that are open to
you. When the parents wish to
know whether the unborn baby
has sickle cell disease, testing can
be performed as early as the tenth
week of pregnancy.
Your child's primary care provider or
a hematologist (blood doctor)
Produced by: Northern California
Comprehensive Sickle Cell Center
Supported by: NIH grant HL20985
Written by: Ilana Mittman, M.S., Genetic Counselor
Edited by: William M. Lande, M.D.
Cell photographs: Margaret R. Clark, UCSF
Design: Lydia Young, UCSF Publications Office
This pamphlet was reproduced by the
California Department of Health Services,
Genetic Disease Branch, with permission of
San Francisco General Hospital.
Revised 2006
Reviewed 2012
Source: California Department of Public Health; http://www.cdph.ca.gov
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Sickle Cell Disease
Sickle Cell Disease is an inherited disorder that affects the hemoglobin, a molecule in red
blood cells, which helps to deliver oxygen throughout the body. These are normal red blood
cells with normal hemoglobin (AA hemoglobin). These cells appear round and are very flexible.
These normal cells live for about 120 days.
These are red blood cells from a person
who has Sickle Cell Disease. Their red
blood cells can lose their normal round
shape and change to a sickle or
crescent shape under certain conditions
such as low oxygen. If oxygen does not
get to the body’s tissues, it will cause
pain and begin to weaken and
deteriorate the tissues. Sickled cells
cannot hold onto oxygen as well as
normal red blood cells. These sickled
cells live for approximately 14 to 21
days instead of the normal 120 days.
Normal round shape
Sickled crescent shape
Sickled crescent shape
These are normal shaped red blood cells
and sickled red blood cells in the blood
vessels. Normal shaped blood cells move
easily through the blood vessels. It is very
difficult for sickled blood cells to pass
through blood vessels because of their
shape. Sickled blood cells can cause
blockages in the vessels leading to many of
the problems seen in Sickle Cell Disease.
Normal round shape
Source: New England Newborn Screening Program; Images Provided By:http://www.fi.edu; http://uvahealth.com;
http://www.gemssforschools.org
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Additional Support and Resources
Local Organizations
Financial Assistance
New England Newborn Screening Program
University of Massachusetts Medical School
305 South Street
Jamaica Plain, MA 02130
Telephone: (617) 983-6300
Website: www.umassmed.edu/nbs
Mass Health
Telephone: 1-800-841-2900 (general info)
1-800-332-5545 (to apply)
Website: www.mass.gov/masshealth
National Organizations
American Red Cross
Telephone: 1-800-GIVE-LIFE
Website: www.newenglandblood.org
National Society of Genetic Counselors
Telephone: (312) 321-6834
Website: www.nsgc.org
Baby’s First Test
Facts about newborn screening
Website: www.babysfirsttest.org
Also known as Medicaid, this is a program of
comprehensive medical coverage for low and
moderate income residents of Massachusetts. Many
kinds of coverage are available. Some programs
include prescription drug coverage, as well as
transportation assistance to medical appointments.
If you are eligible for Mass Health benefits, you most
likely are eligible for Prescription for Public
Transportation and WIC (please check with your
primary care doctor or social worker)
WIC
Telephone: 1-800-942-1007
Website: www.mass.gov/wic
Supports low income woman and children up to age
five years by providing foods to supplement
nutritional needs.
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Authors’ Notes
We encourage you to be proactive and to learn all about Sickle Cell Trait. Go ahead, look up
information and ask your child’s doctor!
Acknowledgements
The following assisted in compiling and reviewing “A Parent’s Guide to Sickle Cell Trait”:
Claire Hughes, BS, Follow Up Coordinator, New England Newborn Screening Program
Seema Jamal, MSc, LCGC, CCGC, Division of Genetic Medicine, University of Washington
Patricia Kavanagh, MD, Division of General Pediatrics, Boston Medical Center
Philippa Sprinz, MD, MSc, Division of Pediatric Hematology/Oncology, Boston Medical Center
Tahlia Wolfgang, MPH, Division of General Pediatrics, Boston Medical Center
Compiled 2012
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