Expression of genetic peripheral neuropathies in South African children

Genetic peripheral neuropathies have prevalence of 1:2500-1:10,000 in populations of European ancestry but are underreported in African populations. This retrospective cross-sectional study described 64 children with genetic peripheral neuropathy attending a neuromuscular disease centre in South Africa. Twenty-one children (21/64, 33 %) had confirmed molecular diagnoses, and 43/64 (67 %) were diagnosed via histology and neurophysiology. In seven children, next generation sequencing did not identify a causative variant. The identified genetic causes were PMP22 duplications (n = 11), and variants in ATL1 (n=1), IGHMBP2 (n = 2), MPZ (n = 1), MFN2 (n = 1), MTMR2 (n = 2), SH3TC2 (n = 1), SLC12A6 (n = 1), and SLC52A3 (n = 1). Axonal neuropathy was most common (47/64, 73 %), affecting 9/12 children with African, 17/26 Mixed, and 21/26 European ancestry. Only two of the 11 children with PMP22 duplication were of Indigenous Black African ancestry. Access to genetic closure for children in sub-Saharan Africa remains a challenge due limited access to genetic testing. In this study there was a predominance of unsolved axonal diseases. PMP22-related CMT1A, appeared rare in children of Indigenous Black African ancestry. More research is needed to elucidate the genetic underpinnings of neuropathies in Africa, for informed and relevant genetic and clinical diagnostic protocols for local patients.