Sural nerve conduction study: Reference values in the Algerian population

Objectives: The sural nerve is the most tested sensory nerve in the lower extremities in the electrodiagnostic assessment of peripheral neuropathies. This study presents the reference values of the sural nerve conduction study (NCS) from a significant sample of the Algerian population. Methods: This is a prospective study of right sural NCS in healthy subjects based on the later recommendations of AANEM-NDTF. The nature of the distribution of each electrophysiological parameter was therefore determined. The lower and upper limits were calculated by using the 5th and 95th percentiles respectively and a logarithmic transformation was performed for Sensory Nerve Action Potential (SNAP) amplitude distribution. Results: 115 subjects aged between 20 and 60 years were selected, including 58 women and 57 men. Unlike Sensory Nerve Conduction Velocity (SNCV), the distribution of SNAP amplitude is not Gaussian. The lower limit of SNAP amplitude was 7.70 µV when using the 5th percentile and 6.80 µV by using the Standard Deviation (SD) method after log transformation. Similarly, the lower limit of SNCV was 43 m/s. The SNAP amplitude was greater in women and decreased with age, height and BMI. Conclusion: The values found in this study are comparable to those published in the literature. It may be more appropriate to determine the reference values using percentiles as recently recommended by several authors

A recurrent homozygous LMNA missense variant p.Thr528Met causes atypical progeroid syndrome characterized by mandibuloacral dysostosis, severe muscular dystrophy, and skeletal deformities

Atypical progeroid syndromes (APS) are premature aging syndromes caused by pathogenicLMNA missense variants, associated with unaltered expression levels of lamins Aand C, without accumulation of wild-type or deleted prelamin A isoforms, as observed inHutchinson-Gilford progeria syndrome (HGPS) or HGPS-like syndromes. A specific LMNAmissense variant, (p.Thr528Met), was previously identified in a compound heterozygousstate in patients affected by APS and severe familial partial lipodystrophy, whereas heterozygositywas recently identified in patients affected by Type 2 familial partial lipodystrophy.Here, we report four unrelated boys harboring homozygosity for thep.Thr528Met, variant who presented with strikingly homogeneous APS clinical features,including osteolysis of mandibles, distal clavicles and phalanges, congenital muscular dystrophy with elevated creatine kinase levels, and major skeletal deformities. Immunofluorescenceanalyses of patient-derived primary fibroblasts showed a high percentage ofdysmorphic nuclei with nuclear blebs and typical honeycomb patterns devoid of laminB1. Interestingly, in some protrusions emerin or LAP2α formed aberrant aggregates, suggestingpathophysiology-associated clues. These four cases further confirm that a specificLMNA variant can lead to the development of strikingly homogeneous clinical phenotypes,in these particular cases a premature aging phenotype with major musculoskeletalinvolvement linked to the homozygous p.Thr528Met variant