Clinic Meets Goal Early in SMA Carrier Screening Among Amish, Mennonites

Meeting its goal in less than half the time, the Clinic for Special Children (CSC) in Pennsylvania Dutch Country has completed its program to identify spinal muscular atrophy (SMA) carriers among Amish and Mennonite communities across 15 states.

The nonprofit CSC conducted 2,177 tests in 15 months, exceeding its goal of 2,000 tests over three years. In all, the Spinal Muscular Atrophy Prevention Readiness program identified 318 individual carriers and nine carrier couples.

The testing provided crucial awareness — when both parents are SMA carriers, there’s a 25% chance their baby will have the autosomal recessive neurodegenerative disease — to this demographic, collectively known as “plain” individuals and couples.

Located in southeastern Pennsylvania’s rural Lancaster County, where Amish and Mennonites comprise nearly a fifth of the population in some areas, the CSC provides primary clinical care and advanced lab service to children and adults who have genetic or other complex disorders, including SMA.

The clinic launched its SMA prevention readiness program in 2018, enlisting the help of midwives and other community leaders to offer free SMA carrier testing to the Amish and Mennonite communities in 15 states. Overall, SMA is roughly five times more prevalent among the Amish and Mennonites than in the general U.S. population, in which 1.4% of African-Americans and 2.1% of whites are carriers. Because the population is relatively isolated, it has a higher incidence of rare recessive disorders, the CSC told SMA News Today in a profile last year.

Through the testing program, three infants were identified at birth as having SMA. All were treated pre-symptomatically with Zolgensma (onasemnogene abeparvovec-xioi), a gene therapy that targets SMA’s underlying genetic cause. Zolgensma, developed by AveXis later acquired by Novartis, was approved by the U.S. Food and Drug Administration in 2019.

Six at-risk infants were tested but did not have the disease.

The number of individuals found to be carriers exceeds the 1-in-25 carrier frequency of the general Mennonite population. In literature announcing the AveXis-funded program, the CSC states that most Mennonite carriers are unaware of their status, and many have no family history of the disease.

Still, the number of individuals identified as carriers reflects the effectiveness of the program’s cascade screening, the CSC said. Cascade testing refers to the performance of genetic counseling and testing in blood relatives of individuals who have been identified as having specific genetic mutations.

Located just outside the village of Strasburg, in part of what’s known as Pennsylvania Dutch Country, the CSC was founded in 1989. Today, the clinic has about 1,100 active patients and is recognized as a global leader in translational and precision medicine. It’s supported largely through donations and community fundraising.

Before federal approval of disease modifier Spinraza (nusinersen), followed by Zolgensma, therapies merely managed SMA symptoms. Because Spinraza and Zolgensma are best administered before symptoms are evident, genetic diagnoses are vital. One effective way of identifying disease risk is through adult carrier testing.

SMA is believed to affect between 10,000 and 25,000 children and adults in the United States.