Should gamete donors be tested for spinal muscular atrophy?

OBJECTIVE

To report two cases of spinal muscular atrophy (SMA) after artificial insemination and to discuss why genetic screening of the disease may be justified in gamete donors.

DESIGN

Case report.

SETTING

Academic departments of genetics and obstetrics.

PATIENT(S): A 32-year-old woman with two successive assisted pregnancies.

INTERVENTION(S): Molecular studies of the SMN1 (survival motor neuron), the determining gene of the disease. MAIN OUTCOME MEASURE(S); Prenatal testing to detect a homozygous deletion of the SMN1 gene; carrier diagnosis by quantitative analysis to detect a single or double dose of exon 7 in the SMN1 gene.

RESULT(S): After a first assisted pregnancy, an SMA child with a homozygous deletion of the SMN1 gene was born. In the second assisted pregnancy, using sperm from a different donor, a fetus with a homozygous deletion of SMN1 was detected. Carrier status in the donor was confirmed by a single dose of SMN1 in the quantitative analysis.

CONCLUSION(S): Genetic screening of SMA carrier status by quantitative analysis of the SMN1 gene should be performed in gamete donors when the recipient is a known carrier. Cost-benefit analysis should be made to consider the inclusion of the test in prospective gamete donor programs.