Congenital adrenal hyperplasia (CAH) is an autosomal recessive disorder and affects approximately 1 in 15,000 births in the United States. CAH is one of the disorders included on the Newborn Screening (NBS) Recommended Uniform Screening Panel. The commonly used immunological NBS test is associated with a high false positive rate and there is interest in developing second-tier assays to increase screening specificity. Approximately 90% of the classic forms of CAH, salt-wasting and simple virilizing, are due to mutations in the CYP21A2 gene. These include single nucleotide changes, insertions, deletions, as well as chimeric genes involving CYP21A2 and its highly homologous pseudogene CYP21A1P. A novel loci-specific PCR approach was developed to individually amplify the CYP21A2 gene, the nearby CYP21A1P pseudogene, as well as any 30 kb deletion and gene conversion mutations, if present, as single separate amplicons. Using commercially available CAH positive specimens and 14 families with an affected CAH proband, the single long-range amplicon approach demonstrated higher specificity as compared to previously published methods.

Spinal muscular atrophy (SMA) was added to the HHS Secretary’s Recommended Uniform Screening Panel for newborn screening (NBS) in 2018, enabling early diagnosis and treatment of impacted infants to prevent irreversible motor neuron damage. In anticipation of supporting SMA newborn screening, scientists at the U.S. Centers for Disease Control and Prevention (CDC) have worked towards building resources for public health laboratories in four phases since 2013. In Phase 1, CDC established a real-time PCR assay, which uses a locked nucleic acid probe to attain the needed specificity, to detect SMN1 exon 7. In Phase 2, we developed quality assurance dried blood spot materials made with transduced lymphoblast cell lines established from de-identified SMA patients, carriers, and unaffected donors. In 2021, CDC implemented Phase 3, a proficiency testing program, that now supports 115 NBS labs around the world. We are currently completing Phase 4, which includes the implementation of an external SMA quality control material program. Also, during this time, CDC has provided individual technical assistance to NBS programs and bench training to NBS scientists during our annual molecular workshop. These CDC-led activities have contributed to the rapid and full implementation of SMA screening in all 50 U.S. states as of February 2024.