gene therapy for the treatment of SCID

[K06100]

A 37-year-old woman gives birth to her third
healthy child. He is discharged from the hospital
with her at 2 days of life. For the fi rst 3
months of his life, however, his parents note
poor weight gain, chronic diarrhea, and persistent
diaper rash. Complete blood count reveals
a paucity of lymphocytes, and antibody staining
demonstrates a defi ciency of the X-linked
interleukin-2 receptor chain. The baby is diagnosed
with X-linked severe combined immunodefi
ciency (SCID). His parents are told that
the standard of care for him is a bone marrow
transplant from a major histocompatibility
complex-matched related donor. His two sisters
are tested and are not matches. His parents are
interested in exploring the option of gene therapy.
Which of the following concerns is unique
to the use of gene therapy for the treatment of
SCID?

(A) Graft-versus-host disease
(B) Increased risk of failure
(C) Increased susceptibility to viral illness in
the future
(D) Ineffi cient response to vaccines in the future
(E) Leukemia

[anomali]

not sure on this one but would go with leukemia....

[step_enhancer]

guessing B ......

[cingulate.gyrus]

(A) Graft-versus-host disease

Gene therapy for SCID is with ADA..
As the child develop immunity he may react against his own antigen...As he may not have developed class switching and clonal deletion against self antigen..

Its my logic not shure

[K06100]

The correct answer is E. Patients with X-linked
SCID and no matched related donor are very
good candidates for stem cell gene therapy.
The defect in the X-linked interleukin-2 receptor
chain gene is known, making this disease a
prototype for gene treatment. The fi rst gene
therapy in patients with SCID was performed
in 1991, and involved transduction with a retroviral
vector with clinical improvements documented
in all patients. Trials have continued
and several patients have been successfully
treated in this fashion. A signifi cant number,
however, have developed a rapidly fatal leukemia,
a transformation thought to result from
the gene insertion into patient cells with oncogenic
action.
Answer A is incorrect. GVHD is not a risk in
gene therapy patients, as they are not undergoing
bone marrow transplant.
Answer B is incorrect. Both gene therapy and
bone marrow transplant carry a 30%–40% risk of
failure. Gene therapy is much less studied, but
has had similar success rates to bone marrow
transplant in the small population in question.
Answer C is incorrect. No difference in susceptibility
to illness has been demonstrated
with the use of gene therapy in treating SCID.
Answer D is incorrect. Patients treated with
gene therapy have been shown to respond well
to clinical vaccinations, as have those treated
with bone marrow transplant.