Cross-Leg Microvascular Free Anterolateral Thigh Flap as a Safe, Viable, and Reserve Option for Reconstruction in a Vessel-Depleted Limb

We present the case of a 36-year-old male patient with a posttraumatic composite defect of the lower two-thirds of the anterior aspect of the left leg with exposed necrotic tibia in an old, neglected type 3b fracture of the tibia of 9-month duration. The options for definitive soft-tissue cover include microvascular free tissue transfer and cross-leg flaps. In trauma cases, the surrounding tissue is usually damaged, and the recipient vessels are frequently implicated, ruling out the use of a microvascular free flap. Cross-leg flaps are unachievable due to large defect sizes and lack of appropriate donor tissue. In this case report, we highlight the use of cross-leg microvascular free anterolateral thigh (ALT) flap cover for the composite leg defect. By presenting our case, we aim to advocate the clinical application of cross-leg free flap surgery in vessel-depleted limbs as a safe and viable option

NANS-mediated synthesis of sialic acid is required for brain and skeletal development.

We identified biallelic mutations in NANS, the gene encoding the synthase for N-acetylneuraminic acid (NeuNAc; sialic acid), in nine individuals with infantile-onset severe developmental delay and skeletal dysplasia. Patient body fluids showed an elevation in N-acetyl-D-mannosamine levels, and patient-derived fibroblasts had reduced NANS activity and were unable to incorporate sialic acid precursors into sialylated glycoproteins. Knockdown of nansa in zebrafish embryos resulted in abnormal skeletal development, and exogenously added sialic acid partially rescued the skeletal phenotype. Thus, NANS-mediated synthesis of sialic acid is required for early brain development and skeletal growth. Normal sialylation of plasma proteins was observed in spite of NANS deficiency. Exploration of endogenous synthesis, nutritional absorption, and rescue pathways for sialic acid in different tissues and developmental phases is warranted to design therapeutic strategies to counteract NANS deficiency and to shed light on sialic acid metabolism and its implications for human nutrition