From the treatments of Ashanthi DeSilva in 1990 which is considered gene therapys first success until 2014 around 60 patients were treated for either ADA-SCID or X-SCID using retroviruses vectors but as previously mentioned the occurrence of cases developing leukemia forced to make changes to improve safety, more recently in 2019 a new method using an altered version of the HIV virus as a lentivirus vector was reported in the treatment of 8 children with X-SCID, and in 2021 the same method was used in 50 children with ADA-SCID obtaining positive results in 48 of them.There are also some non-curative methods for treating SCID. Reverse isolation involves the use of laminar air flow and mechanical barriers (to avoid physical contact with others) to isolate the patient from any harmful pathogens present in the external environment. A non-curative treatment for patients with ADA-SCID is enzyme replacement therapy, in which the patient is injected with polyethyleneglycol-coupled adenosine deaminase (PEG-ADA) which metabolizes the toxic substrates of the ADA enzyme and prevents their accumulation. Treatment with PEG-ADA may be used to restore T cell function in the short term, enough to clear any existing infections before proceeding with curative treatment such as a bone marrow transplant. Epidemiology
The most commonly quoted figure for the prevalence of SCID is around 1 in 100,000 births, although this is regarded by some to be an underestimate of the true prevalence; some estimates predict that the prevalence rate is as high as 1 in 50,000 live births.
Classification
Diagnosis
Early diagnosis of SCID is usually difficult due to the need for advanced screening techniques. Several symptoms may indicate a possibility of SCID in a child, such as a family history of infant death, chronic coughs, hyperinflated lungs, and persistent infections. A full blood lymphocyte count is often considered a reliable manner of diagnosing SCID, but higher lymphocyte counts in childhood may influence results. Clinical diagnosis based on genetic defects is also a possible diagnostic procedure that has been implemented in the UK.Some SCID can be detected by sequencing fetal DNA if a known history of the disease exists. Otherwise, SCID is not diagnosed until about six months of age, usually indicated by recurrent infections. The delay in detection is because newborns carry their mothers antibodies for the first few weeks of life and SCID babies look normal. Newborn screening
Several countries test all newborns for SCID as a part of routine newborn screening. All states in the U.S. are performing screening for SCID in newborns using real-time quantitative PCR to measure the concentration of T-cell receptor excision circles. United Kingdom intends to introduce newborn screening for SCID in September 2021. Treatment
The most common treatment for SCID is bone marrow transplantation, which has been very successful using either a matched related or unrelated donor, or a half-matched donor, who would be either parent. The half-matched type of transplant is called haploidentical. Haploidentical bone marrow transplants require the donor marrow to be depleted of all mature T cells to avoid the occurrence of graft-versus-host disease (GVHD).