Skeletal dysplasias (SD) are rare genetic disorders of bone. SD encompasses a genetically heterogeneous, rapidly expanding group of over 750 distinct disorders with over 550 associated genes5. Diagnostic yield of WES is reported to be relatively higher (40%- 60%) in SD group compared to other rare disease categories4. However still nearly 50% of the affected individuals can not get a molecular diagnosis. Data obtained from deep phenotyping is one of the most important parameters that increases the diagnostic yield of WES/WGS analysis6. Deep phenotyping in these patients mandates a multidisciplinary approach, involving clinical geneticists, radiologists, orthopaedic surgeons, and endocrinologists, experienced in SD. Many recent studies show that reanalysis of WES/ WGS data every 1-2 years in patients with undiagnosed rare diseases provides an additional diagnosis rate of up to 12 %. Although there is no reanalysis study conducted specifically in SD patients, it has been foreseen that re-phenotyping of patients by experienced multidisciplinary groups can improve the diagnostic rate of reanalysis. As clinical geneticists working on rare diseases, patients with skeletal dysplasias/genetic disorders of bone/growth disorders constitute an important part of our daily practice. WES/ WGS analysis is helpful in diagnosis in this group of patients; however, even with the WGS analysis, a definite diagnosis could not be reached in some patients. The primary aim of this multidisciplinary study is to combine efforts to reanalyze WES/WGS raw data with current bioinformatic pipelines and deep phenotyping by lead SD experts. WES/WGS and clinical data from undiagnosed patients with a possible skeletal dysplasia/rare genetic bone disease followed at Acıbadem University, Pediatric Genetics Clinic, between 2013-2023 will be included in the study. The clinical and radiographic findings will be discussed in multidisciplinary clinical meetings(MCM) with attendance of all clinicians from Turkey and France. After MCM, bioinformatics teams on both sides will reanalyze the NGS data. The consensus analysis data from the bioinformatics teams will be shared with the clinical team in joint meetings for variant-phenotype correlation and diagnosis. With this project We expect to expand our knowledge of genotype-phenotype correlations in this ultra-rare disease group, disseminate study results by publishing as a research paper, create resources for possible therapeutic development research by increasing our knowledge of the pathophysiological pathways and build a long-term cooperation with the French group to continue communication on new research areas in rare diseases that may emerge in the future.