Figure 3: The absence of a 2.8Kb band in a female patient (9606) is consistent with complete skewed inactivation of the normal allele. Different band intensities detected in the unaffected mother indicate a possible skewed inactivation in favor of the normal allele. Both findings were confirmed by FMRP test where less than 5% FMRP positive lymphocytes were detected in the patient and 55- 65% in the mother.