Gene Therapy for IGHMBP2-Related Diseases

Inclusion Criteria: * Confirmation of two pathogenic variants in the IGHMBP2 gene from a CLIA-certified lab * Pre-ambulant (not yet walking and less than 18 months) or ambulant (as defined by the ability to walk 10 meters without assistance) or non-ambulant (inability to walk more than 10 meters unassisted) * Ability to cooperate with functional assessments as per PI's discretion Exclusion Criteria: * Prior participation in a gene or cell therapy program for any kind. * Immunizations of any kind in the month prior to the study. * Active infection based on clinical observations * Serological evidence of HIV infection, or Hepatitis B or C infection * Diagnosis of (or ongoing treatment for) an autoimmune disease * Persistent leukopenia or leukocytosis (WBC ≤ 3.5 10\^3/μL or ≥ 20.0 10\^3/μL) or an absolute neutrophil count \< 1.5 10\^3/μL * Abnormal liver function as indicated by an elevated GGT (\>2X normal if no other laboratory abnormalities), bilirubin and/or abnormal PT/INR * Concomitant illness or requirement for chronic drug treatment that in the opinion of the PI creates unnecessary risks for gene transfer * AAV9 binding antibody titers \> 1:50 as determined by ELISA immunoassay performed by Athena Diagnostics * Abnormal laboratory values in the clinically significant range, based upon normal values in the Nationwide Children's Hospital Laboratory * Diagnosis of any other systemic illness that increases the risk of gene transfer per the PI's opinion; Has a medical cond…