Newborn infant screening for spinal muscular atrophy: Chances and challenges

Current Status of Newborn Bloodspot Screening Worldwide 2024: A Comprehensive Review of Recent Activities (2020-2023)

Newborn bloodspot screening (NBS) began in the early 1960s based on the work of Dr. Robert "Bob" Guthrie in Buffalo, NY, USA. His development of a screening test for phenylketonuria on blood absorbed onto a special filter paper and transported to a remote testing laboratory began it all. Expansion of NBS to large numbers of asymptomatic congenital conditions flourishes in many settings while it has not yet been realized in others. The need for NBS as an efficient and effective public health prevention strategy that contributes to lowered morbidity and mortality wherever it is sustained is well known in the medical field but not necessarily by political policy makers. Acknowledging the value of national NBS reports published in 2007, the authors collaborated to create a worldwide NBS update in 2015. In a continuing attempt to review the progress of NBS globally, and to move towards a more harmonized and equitable screening system, we have updated our 2015 report with information available at the beginning of 2024. Reports on sub-Saharan Africa and the Caribbean, missing in 2015, have been included. Tables popular in the previous report have been updated with an eye towards harmonized comparisons. To emphasize areas needing attention globally, we have used regional tables containing similar listings of conditions screened, numbers of screening laboratories, and time at which specimen collection is recommended. Discussions are limited to bloodspot screening.

Screening and prenatal diagnosis of survival motor neuron gene deletion in pregnant women in Zhaoqing city, Guangdong Province

OBJECTIVE

A total of 5,200 pregnant women in Zhaoqing city, Guangdong Province, were screened to identify spinal muscular atrophy (SMA) mutation carriers to guide the prevention of SMA and prevent the birth of children with SMA.

METHODS

Exons 7 and 8 (E7 and E8) of the survival motor neuron (SMN) 1 gene were detected in women using real-time fluorescence quantitative polymerase chain reaction. SMN1 and SMN2 copy numbers in those who were initially identified as carriers were verified via targeted region capture and next-generation sequencing. When both partners were identified as carriers, prenatal diagnosis of the fetus was performed.

RESULTS

Among the screened women, 75 SMA carriers (71 cases had both E7 and E8 heterozygous deletions and 4 cases only had an E7 heterozygous deletion) were identified, with a carrier frequency of 1.44% (95% confidence interval: 1.31-1.65%). Three couples where both spouses were identified as SMA carriers, and their three fetuses were subjected to prenatal genetic analysis. Of the three, one had homozygous deletions of E7 and E8 and the other two had heterozygous deletions of E7 and E8. After a detailed prenatal consultation, the former couple decided to terminate the pregnancy.

CONCLUSION

Through screening and prenatal diagnosis of pregnant women in Zhaoqing city, Guangdong Province, the incidence of SMA can be reduced, prevention of birth defects can be improved, incidence of birth defects can be effectively minimized.