Date of Completion

Summer 8-24-2019

Thesis Advisor(s)

Judy Brown

Honors Major

Diagnostic Genetic Sciences


Congenital, Hereditary, and Neonatal Diseases and Abnormalities | Medical Genetics


Spinal Muscular Atrophy (SMA) is a genetic neuromuscular disorder characterized by progressive muscle weakness due to the degeneration of motor neurons. SMA is caused by a homozygous deletion, mutation or rearrangement in the Survival Motor Neuron 1 (SMN1) gene. Survival Motor Neuron 2 (SMN2) is located tandem to SMN1 and is identical to SMN1 except for a single nucleotide substitution in exon 7. SMA diagnosis and carrier status can be determined by droplet digital PCR (ddPCR). This study sought to validate Bio-Rad’s ddPCR SMN1and SMN2 gene determination copy number assay for SMA diagnosis and screening using buccal swabs specimens. Buccal swab specimens would be used clinically as an alternative in instances where SMA diagnosis is required for pediatric patients and a blood draw would cause distress for the child. DNA was extracted from samples provided by 20 adult human volunteers. Volunteers donated blood and cheek cells via two types of buccal swab specimens for comparison. DNA was extracted with an automated method and manually, depending on the specimen. SMN1 and SMN2 copy number results were then assessed using Bio-Rad’s ddPCR SMN1 and SMN2 gene determination copy number assay. The buccal swab samples did not provide reliable or accurate copy number results in comparison to blood samples. The buccal swabs investigated in this experiment are therefore not suitable for clinical use. Future investigations should assess whether other non-invasive options of DNA collection could be used clinically for SMA diagnosis and screening.