Severe combined immune deficiency : diagnosis

Clinical manifestations, diagnosis of SCID.

Clinical manifestations

too frequent infections - the most common manifestation of SCID children first year of life.Usually these infections are not like infections that normal children are sick (eg, frequent colds).

infections in infants with SCID can experience more serious and even endanger the patient's life;These include pneumonia, meningitis and blood infections.

Widespread use of antibiotics for the treatment of even minimal infections has changed the character of manifestations of SCID, in connection with which a physician observing the child's first year of life, must have sufficient alertness to recognize this condition.In infants with SCID Infection occurs upon contact with microorganisms that cause infections in normal children, as well as microorganisms and vaccines that are not usually harmful to children with normal immunity.

Among the most dangerous - the microorganism Pneumocystis jiroveci, causing pneumonia (PCP), quickly leading to d

eath in late detection and treatment.Another very dangerous organism is the chickenpox virus.Chickenpox is an unpleasant disease that causes a lot of discomfort in normal children;its symptoms are usually limited to the skin and mucous membranes and tested within a few days.In infants with SCID is a disease that can be fatal, as the recovery does not occur, and may spread to the lungs, liver and brain.

Cytomegalovirus (CMV), which nearly all of us are in the salivary glands, may cause fatal pneumonia in infants with SCID.

other dangerous viruses for children with SCID are herpes simplex virus, adenovirus, parainfluenza 3, Epstein-Barr virus (EBV virus or infectious mononucleosis), polio virus, measles virus and rotavirus.

Since vaccines are administered to children for the prevention of chickenpox, measles and rotavirus are made from live viruses, children with SCID can be infected by them by immunization.If you know that someone in the family previously suffered or are currently suffering from SCID, the new children of this family can not be vaccinated until then, until they will be excluded SCID.

treatment of fungal (yeast) infections may be much more difficult.For instance, mouth infection fungi of the genus Candida (thrush) is common in newborns, but usually goes away or after oral administration of simple drugs.In contrast, children with SCID thrush in the mouth is kept, despite all treatment.It can be less pronounced, but is not fully reversible or recurs immediately after the cessation of treatment.It may also be hit by the area of ​​contact with the diaper.In
children with SCID can candida pneumonia, abscesses, esophageal infection or even meningitis.

Persistent diarrhea, which prevents the development of the child, is a frequent violation when SCID.It can lead to significant weight loss and malnutrition.Diarrhea can be caused by the same bacteria, viruses or parasites that infect normal children.However, the SCID of these microorganisms is very difficult to get rid of after infection.

Children with SCID skin may be affected.Can a chronic infection of the skin in the same fungus (genus Candida), which infects the mouth and causes thrush.In infants with SCID may cause a rash, which is misdiagnosed as eczema, but in fact it is caused by reaction of the parent of T-cells (received into the bloodstream of the patient SCID baby before birth) with newborn tissues.This reaction is called the reaction of tissue incompatibility.


Usually suspicion of this disease first occurs in the presence of clinical manifestations described above.However, in some cases in the family already has a child with SCID, and the family history can help in the diagnosis, even before the development of the child has any symptoms.

The easiest way to diagnose this condition - count the baby's blood lymphocytes (or umbilical cord blood lymphocytes).This is done by performing two analyzes counting all cellular elements of blood and determining blood counts (percentage of various white blood cells), by which a physician can determine the absolute number of lymphocytes (the total number of blood).Typically, in one cubic millimeter of blood of the child first year of life are more than 4000 lymphocytes, of which 70% are T-cells.

Because SCID children with no T-cells, they usually total lymphocytes decreased significantly.When SCID in one cubic millimeter of blood contains an average of 1,500 cells.If you found a low lymphocyte count should confirm this result in the re-examination.If the newly found low levels of lymphocytes, you should immediately perform a count T cells and determining their function to confirm or exclude the diagnosis.

Different types of lymphocytes can be painted with special dyes and count.Thus it is possible to determine the total number of T-lymphocytes, the number of T-helper lymphocytes, the number of T-killer lymphocytes and the number of B- and NK-cells.Since the decline in the number of different types of lymphocytes can occur in other conditions, the most important research studies are T-cell function.The most definitive test for the function of T-lymphocytes in a room consist blood lymphocyte cell cultures, treatment of various stimulants, followed by incubation for several days.

Normal T-lymphocytes react to these stimulants cell division.Votlichie them, lymphocytes SCID patients generally do not react to these stimuli.

for SCID is characterized by very low levels of immunoglobulins.In most cases (but not always) a reduction in all the classes of immunoglobulins (i.e., IgG, IgA, IgM and IgE).Since IgG mother enter the bloodstream of the fetus through the placenta, their levels are almost normal in the body of a newborn baby and the first year of life.Therefore, the immunoglobulin deficiency may be recognized by only a few months when of IgG, transferred from the mother's body, metabolized and excreted.

Identification SCID possible before the birth of the child, if the family already has a SCID patient is a child, and if the detected molecular defect.If earlier the birth of sick child carried the mutation analysis, you can perform a diagnostic study of the unborn baby (embryo or fetus with amniotic tissue).This can be done by molecular analysis of chorionic cilia or amniotic fluid containing fetal cells and obtained from the uterine cavity by amniocentesis.

Even if the molecular abnormalities in the family is not fully characterized, there are research methods to eliminate some defects.For example, adenosine deaminase deficiency can be eliminated by enzymatic analysis of cell cilia CVS or amnion cells.If it is proved that this form of SCID is inherited as an X-linked recessive trait, and a female fetus, it should not be struck by the disease.

In most cases, unless you consider the possibility of termination of pregnancy due to the destruction of the fetus, diagnosed at birth by examining blood lymphocytes of umbilical cord, as the above procedures, as well as prenatal blood samples for the study of lymphocytes, carry some risk to the fetus.

Early detection before the child's likelihood of infection occur, it is extremely important, since a bone marrow transplant, performed during the first 3 months of life leads to success in 96% of cases.Indeed, recent advances in science make it possible to carry out screening of all newborns to detect SCID soon after birth.


Probably all types of SCID is caused by genetic disorders.These disorders can be inherited from a parent or caused by new mutations in the patient's body of the child.As previously noted, this disorder can be inherited as an X-linked (coupled with the sex chromosomes) sign when the gene is inherited from the mother or as one of many autosomal recessive defects where both parents are carriers of the defective gene.

Parents should apply to genetic counseling to be aware of the risk in subsequent pregnancies.It should be noted that the decision on whether or not these parents need to have more children, may not be right or wrong.Such a decision should be made taking into account the features of the family structure, the basic outlook of the parents, their religious beliefs and upbringing, their perception of the impact of the disease on their lives and the lives of other family members.There are countless factors that may be different in different families.

Article courtesy of a worldwide organization IPOPI, working to improve the lives of people with primary immunodeficiency.
Copyright 2007 owned fund Immune Deficiency Foundation, USA."Guidelines for the primary immunodeficiency diseases for patients and their families", from which the material is taken under the license, was developed Immune Deficiency Foundation with support from Baxter Healthcare Corporation.

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