A search for CGG repeats in the LRP12, GIPC and RILPL1 genes in 1555 cases of hereditary peripheral neuropathy without a genetic diagnosis found 44 cases of CGG repeats in the LRP12 gene (and none in the GIPC and RILPL1 genes):
- the number of CGG repeats, less than 100 in 93.2% of cases, ranged from 50 to 152; it was significantly lower than that found elsewhere, in a series of 77 cases of oculo-pharyngo-distal myopathy linked to LRP12;
- Most of the cases for which clinical data were available (29/37) presented with distal weakness of the lower limbs without ptosis, ophthalmoplegia, facial deficit or bulbar involvement;
- two people had lost their ability to walk;
- motor impairment without sensory impairment was detected by electrophysiology in 28 cases;
- seven cases, presenting as one, had both motor and sensory nerve damage;
- twenty-eight people had motor nerve involvement without sensory nerve involvement and 7 had sensory-motor involvement characteristic of Charcot-Marie-Tooth disease.
- the incidence of facial, ocular and bulbar involvement, loss of gait, rimmed vacuoles and p62-positive intra-nuclear inclusions was significantly lower than in LRP12-related oculo-pharyngo-distal myopathy.
Of the 2424 cases of hereditary peripheral neuropathies diagnosed between 2007 and 2021 in Japan, CGG expansions in LRP12 represent the fourth most common cause of the 913 genetically determined cases, behind the involvement of MFN2 (150), GJB1 (142) and MPZ (114).
