Abstract
Background
Spinal muscular atrophy (SMA) is a fatal autosomal recessive disorder for which several treatment options, including gene therapy, have become available. SMA incidence has not been well-characterized in most Arab countries where rates of consanguinity are high. Understanding SMA disease epidemiology has significant implications for screening, prevention, and treatment in those populations.
Methods
We preformed SMA diagnostic testing in a clinical multi-national patient cohort (N = 171) referred for hypotonia and/or muscle weakness. In addition, we carried out genetic newborn screening for SMA on 1,252 healthy Emirati newborns to estimate the carrier frequency and incidence of the disease in the United Arab Emirates.
Results
Patients referred for SMA genetic testing were mostly Arabs (82%) representing 18 countries. The overall diagnostic yield was 33.9%, which was higher (> 50%) for certain nationalities. Most patients (71%) had two SMN2 copies and earlier disease onset. For the first time, we estimate SMA carrier frequency (1.5%) and incidence of the disease (1 in 5,990 live births) in the United Arab Emirates. Using birth and marriage rates in two Arab populations (United Arab Emirates and Saudi Arabia), as well as disease incidence in both countries, we show that, besides preventing new cases, premarital genetic screening could potentially lead to $10 to $324 million, respectively, annual cost savings relative to postnatal treatment.
Conclusion
The SMA carrier frequency and incidence we document suggests high potential benefit for universal implementation of premarital genomic screening for a wide range of recessive disorders in Arab populations.