[Genetic and clinical analysis of a child with Shwachman-Diamond syndrome due to compound heterozygous variants of SBDS gene].

OBJECTIVE: To analyze the clinical features and genetic characteristics of a patient with Shwachman-Diamond syndrome (SDS) due to compound heterozygous variants of SBDS gene. METHODS: A female child with SDS who was admitted to the Children's Hospital Affiliated to Zhengzhou University in February 2022 was selected as the study subject. Clinical data of the child was collected. Peripheral blood samples of the child and her elder sister and parents were collected and subjected to whole exome sequencing (WES). Candidate variant was verified by Sanger sequencing. RESULTS: The child, a 1-year-and-1-month-old girl, had mainly manifested with diarrhea, hematochezia, growth retardation and malnutrition, along with increased transaminases and decreased neutrophils and hemoglobin. Anteroposterior X-ray of her left wrist indicated significantly delayed bone age. Colonoscopy revealed that her colorectal mucosa was erosive with oily food residues attached to the intestinal lumen. Genetic testing revealed that she has harbored c.258+2T>C and c.100A>G compound heterozygous variants of the SBDS gene. The c.258+2T>C variant has derived from her father and known to be pathogenic, whilst the other has derived from her mother. Based on the guidelines from the American College of Medical Genetics and Genomics, the c.100A>G variant was classified as likely pathogenic (PM1+PM2_Supporting+PM3+PM5+PP3). CONCLUSION: The compound heterozygous variants of c.258+2T>C and c.100A>G probably underlay the SDS in this child. For children with refractory diarrhea, liver damage and growth retardation, SDS should be suspected, and genetic testing can facilitate the diagnosis and treatment.

[Optimization Design of Interbody Fusion Cage withDifferent Bone Densities Printed in 3D].

Based on the original data of cervical spine, the models of cervical C6 and C7 segments were reconstructed through medical image processing and reverse modeling operations, then the models were assembled to obtain the basic data of interbody fusion cage. According to the basic data, the structures of rectangular porous, gradient porous and octahedral porous interbody fusion cages were established respectively. Maximum force on the adult male neck was applied to the fusion device, and the stress, strain and maximum deformation of the fusion device were solved by finite element analysis. The elastic modulus decrease of the design, and the rectangular porosity structures with different porosity were analyzed and optimized. The results showed that the elastic modulus of the fusion cage with three structures decreased in varying degrees, and the porosity of the interbody fusion cage with rectangular structure was about 60%, which was the most decreased elastic modulus.