Accidental LOPD diagnosis in a young man with no clinical and instrumental evidence of Neuromuscular

A 33 years old man came to our observation because he was found affected with Late Onset Pompe Disease ( after he and his wife decided to undergo a genetic screening for autosomal recessive disorders when they learnt they were expecting a baby He is completely asymptomatic and all tests are normal, namely neurological examination, serum CK levels, EMG, muscle MRI, respiratory and cardiac screening Biochemical analysis in lymphocytes disclosed the 93 reduction of alpha 1 4 glucosidase residual activity in the proband and 30 of reduction in his parents, compared to controls GAA molecular analysis disclosed the “ pathogenic substitution IVS 1 32 13 T>G in homozygosis in the proband This splicing variant occurs in 90 of Caucasian late onset patients and is associated with a broad range of symptom onset The variant was found heterozygous in DNA samples obtained in proband’s unaffected parents and in a chorionic villus sample collected during prenatal genetic testing Several subjects displaying the homozygous IVS 1 32 13 T>G have been described and many of them remain asymptomatic, although a subset develops symptoms with time Our proband was negative for the synonymous variant c 510 C>T which was demonstrated to act as a genetic modifier worsening the effect of the IVS 1 32 13 T>G mutation Given the absence of neuromuscular dysfunction, no replacing therapy has been so far started and the patient is being clinically monitored