Fig. 3. Cramping, growth characteristics and lethal phenotype. (A-C) Fore/hindlimb cramping phenotype in postnatal homozygous Mgn^tZ/tZ mutant at postnatal day 20 (P20). Wild-type (A), homozygous Mgn knockout (B) and heterozygous Mgn knockout (C) mice. When lifted by their tail, Mgn^tZ/tZ mice displayed an obvious fore-/hindlimb clenching phenotype. Neither wild-type nor heterozygous Mgn^+/tZ mice show this phenotype. (D) Phenotypic comparison of Mgn^+/+ and Mgn^tZ/tZ mice at P32. Both animals were on C57BL/6 genetic background. (E) Survival curve of Mgn^tZ/tZ mice. Days of survival of Mgn^tZ/tZ (red line) compared with Mgn^+/+ (green line) and Mgn^+/tZ (blue line) mice. (F) Representative growth curve comparison between littermates. Mean body weight at age P0-P45 is represented by a green line (Mgn^+/+), a blue line (Mgn^+/tZ) and a red line (Mgn^tZ/tZ) with error bars displaying the standard errors of the day-specific means. Arrows indicate the day of death for each of the Mgn^tZ/tZ mice. The mean difference in weight between heterozygous and wild-type mice was 0.227 g (P=0.9475).