discharge newborn thrived well but had a severe motor delay. He was referred to our institution at the age of 3 months with severe hypotonia, hypermobile joints, extremities in a frog-like position, redundant skin, no head control, bell-shaped thorax with pectus excavatum, mild thoracolumbar kyphosis, spina bifida occulta, umbilical hernia, undescended testicles, and talipes calcaneovalgus. Social contact was normal. Metabolic workup and gene analyses for spinal muscular atrophy, myotonic dystrophy type 1 and Prader-Willi syndrome gave normal results. Brain MRI was normal.Electromyoneurography showed myopathy. Muscle biopsy revealed abnormal mitochondria and decreased activities of all respiratory chain complexes.Mitochondriopathy was suspected and ,,mitochondrial-cocktail' therapy was started. At two years of age, the patient was severely hypotonic, with myopathic face, hyperelastic joints and skin, easy bruising, thoracolumbar kyphoscoliosis, and normal mental development. He started to walk at the age of 3.5 years. At the age of 5 years, he developed severe osteoporosis and kyphoscoliosis progressed. Whole exome sequencing (WES) revealed homozygous mutation c.362dupC (p.Glu122fs) in the FKBP14 gene. Conclusion Collagen myopathies should be in the differential diagnosis of floppy infant syndrome. Skin hyperextensibility and improvement of motor function with age may help to distinguish kEDS from collagen VI-related myopathies. Diagnosis can be confirmed by single gene or multigene panel testing. In a diagnostic dilemma, as in this case, in which some findings pointed to the diagnosis of mitochondrial disease, WES could be the best diagnostic approach. Accurate diagnosis ensures optimal patient management, complications insight, and appropriate genetic counselling.