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Severe Combined Immunodeficiency (SCID)

Severe Combined Immunodeficiency (SCID) is a group of rare, life-threatening genetic disorders that affect the immune system. It is characterized by a severely weakened or nearly absent immune response, leaving affected individuals highly susceptible to infections. SCID is sometimes referred to as the “bubble boy disease” due to the case of David Vetter, who lived in a sterile environment to avoid infections.

SCID is caused by mutations in various genes, leading to different forms of the disorder. These mutations primarily affect the development and function of T cells, B cells, and sometimes NK cells – all of which are crucial for a healthy immune system. Symptoms of SCID often appear during infancy, with recurrent infections, failure to thrive, and chronic diarrhea being common signs. Early diagnosis and treatment are crucial for improving the chances of survival.

Early diagnosis and intervention are crucial for improving the outcome of individuals with SCID. Newborn screening programs for SCID have been implemented in many countries to facilitate early detection and treatment.

Advantages of early diagnosis

Timely treatment

Early diagnosis enables prompt initiation of treatment, which can significantly improve the prognosis. Treatments like hematopoietic stem cell transplantation (HSCT), enzyme replacement therapy, or gene therapy can be more effective when started early in life.

Reduced risk of infections

SCID patients are susceptible to life-threatening infections. Early diagnosis allows for the implementation of infection prevention measures, such as isolation, prophylactic antibiotics, and immunoglobulin replacement therapy, reducing the risk of infections.

Better growth and development

By minimizing the occurrence of infections and starting appropriate treatments, early diagnosis can help promote normal growth and development in children with SCID.

Improved survival rates

Early diagnosis and intervention have been shown to improve overall survival rates for SCID patients, particularly when HSCT is performed before the onset of severe infections.

Family planning and genetic counseling

Early diagnosis can provide valuable information for families about the risk of future children being affected by SCID. This can help with family planning and facilitate informed decision-making regarding prenatal testing or in-vitro fertilization with pre-implantation genetic diagnosis.

Psychosocial support

Early diagnosis can help families access essential psychosocial support services to cope with the challenges associated with having a child with SCID. This includes connecting with support groups, mental health professionals, and educational resources to better understand and manage the condition.

Research opportunities

Identifying patients with SCID early can help researchers study the natural history of the disease, evaluate the effectiveness of various treatment options, and develop new therapeutic approaches. This can ultimately contribute to improving the care and outcomes for individuals with SCID.

How Newborn Screening Helps SCID

Newborn screening for Severe Combined Immunodeficiency (SCID) is a crucial tool in the early detection and management of this life-threatening genetic disorder. Screening programs help identify affected infants shortly after birth, which can significantly improve their health outcomes. Here’s how newborn screening helps in the case of SCID:

Early detection

Newborn screening tests, such as the T-cell receptor excision circle (TREC) assay, can detect SCID within the first few days of life. This allows for the identification of affected infants before they develop severe infections or other complications related to their compromised immune system.

Prompt treatment

Once a newborn is diagnosed with SCID through screening, healthcare providers can initiate appropriate treatments, such as hematopoietic stem cell transplantation (HSCT), enzyme replacement therapy, or gene therapy. Early treatment significantly improves the prognosis and increases the likelihood of successful immune reconstitution.

Infection prevention

With early detection, healthcare providers can implement infection prevention measures like isolation, prophylactic antibiotics, and immunoglobulin replacement therapy. These steps help reduce the risk of life-threatening infections and their complications, which are common in SCID patients.

Improved survival rates

Newborn screening has been shown to increase overall survival rates for SCID patients. Early diagnosis and intervention, particularly HSCT performed before the onset of severe infections, significantly improve long-term survival and quality of life.

Better growth and development

Early detection and treatment can promote better overall growth and development for affected children, leading to improved physical, cognitive, and emotional outcomes.

Family planning and genetic counseling

Newborn screening allows families to receive valuable information about their child’s SCID diagnosis, enabling informed decision-making regarding family planning, prenatal testing, or pre-implantation genetic diagnosis for future pregnancies.

Enhanced research opportunities

Identifying SCID patients early through newborn screening can contribute to research efforts aimed at understanding the natural history of the disease, evaluating the effectiveness of various treatment options, and developing new therapeutic approaches. This can ultimately lead to better care and outcomes for individuals with SCID.

How Works Newborn Screening In SCID

Newborn screening for Severe Combined Immunodeficiency (SCID) is a critical public health measure that helps identify affected infants shortly after birth, allowing for early intervention and improved outcomes. The most common method for SCID newborn screening is the T-cell receptor excision circle (TREC) assay.

Here’s how the process works:

1. Blood sample collection

After a baby is born, typically within 24 to 48 hours, a small blood sample is collected from the baby’s heel via a heel prick. This is known as a “dried blood spot” (DBS) sample, and it is used for various newborn screening tests, including SCID.

2. TREC assay

The dried blood spot sample is then analyzed in a laboratory using the TREC assay. TRECs are small DNA byproducts generated during the development of T cells in the thymus. Since SCID patients have significantly reduced or absent T cells, the number of TRECs in their blood is also markedly low.

3. Screening results

If the TREC assay detects abnormally low levels of TRECs, the test result is considered positive or abnormal, indicating that the infant may have SCID or another T-cell lymphopenia condition. It is important to note that the TREC assay is a screening test, not a diagnostic test, and further confirmatory testing is necessary to determine the specific condition.

4. Confirmatory testing

If the initial TREC assay result is positive, the infant will be referred for further diagnostic testing, which may include flow cytometry to assess T cell, B cell, and NK cell counts, and genetic testing to identify specific mutations responsible for SCID or other immunodeficiencies.

5. Diagnosis and treatment

If the confirmatory tests confirm a diagnosis of SCID, the infant can be promptly referred to an immunologist or specialist for appropriate treatment, such as hematopoietic stem cell transplantation (HSCT), enzyme replacement therapy, or gene therapy. Early treatment initiation improves the prognosis and survival rates for SCID patients.

6. Infection prevention

In addition to treatment, healthcare providers can implement infection prevention measures, including isolation, prophylactic antibiotics, and immunoglobulin replacement therapy, to protect the infant from life-threatening infections.

By detecting SCID early through newborn screening, affected infants can receive the necessary care and treatment to improve their health outcomes and overall quality of life.

The available in-depth levels

StepOne®

The StepOne® panel includes Inherited Metabolic Disorders caused by the missed synthesis of important enzymes or the inability to use substances that are essential for life. Currently, only a few diseases are included in a mandatory neonatal screening in some Countries (for instance, in Italy they are only three: phenylketonuria, congenital hypothyroidism, and cystic fibrosis). Bioscience Institute’s expanded metabolic screening allows for the timely detection of  up to 55 diseases.

StepOnePlus®

Parents can ask the Bioscience Institute for a more in-depth level of investigation in order to examine the presence of two more categories of pathologies: Severe Combined ImmunoDeficiency (SCID) and Lysosomal Storage Diseases (LSDs).

SCID (Severe Combined ImmunoDeficiency)

SCID comprises a group of diseases (caused by at least 13 genetic defects) in which the immune system is severely compromised, to the point that the body is unable to defend itself against infectious agents. They generally manifest from the first months of life,  with recurrent infections characterized by a particularly aggressive course.

LSDs (Lysosomal Storage Diseases)

Lysosomal storage diseases are caused by an alteration of any of the functions of lysosomes (organelles responsible for the degradation and the recycling of cell metabolism products). In particular, they are associated with the deficiency or the malfunctioning of the enzymes responsible for their activity.

Request the StepOne® Neonatal Screening

Request now a free consultation for STEPONE®, the expanded metabolic screening for the early rare genetic disorder diagnosis in the newborn. Email info@bioinst.com or fill out the form below to be contacted by one of our experts.

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