Objective:To investigate the clinical and genetic characteristics of peroxisome D-bifunctional protein deficiency (PDBPD) associated with HSD17B4 mutation. Methods:The clinical and genetic characteristics of 2 cases of PDBPD in August 2020, at Children′s Hospital Affiliated to Nanjing Medical University caused by HSD17B4 gene mutation were retrospectively analyzed. Results:Male proband and his sister suffered from neonatal epilepsy, psychomotor development disorders, ataxia, myasthenia, hearing impairment, and foot deformity.The very long chain fatty acids in serum were normal, and brain magnetic resonance imaging (MRI) showed bilateral cerebellar hemisphere atrophy.Electromyography suggested changes in the myoelectricity of multiple peripheral neurogenic lesions.Auditory evoked potential displayed severe bilateral sensorineural hearing loss.Exome sequencing identified compound heterozygous mutations (c.1171G > C, c.686-2A>T) in HSD17B4.The clinical diagnosis was PDBPD, aged 8 and 14 years, respectively. Conclusions:Two cases of HSD17B4 mutation-induced PDBPD were first reported in Chinese mainland, which was in line with its typical clinical manifestations.The newly discovered c. 1171G> C and c. 686-2A>T mutations enriched the HSD17B4 mutation spectrum.

To seek convenient and effective method for reconstruction of edentulous jaw, Maló and his colleagues developed All-on-Four implant immediate-function concept. The principle of All-on-Four is to support the full-arch prosthesis by 4 implants and to achieve immediate loading after surgery. Its advantages include avoiding additional bone grafting, evading critical anatomical structures and immediate prosthesis. In recent years, All-on-Four technique has been widely utilized in clinical practice as a viable approach for edentulous patients. With the auxiliary of guided surgery and biomechanical researches, All-on-Four has achieved predictable clinical results. In this paper, the development, investigation of biomechanics and main points of surgery and prosthesis of All-on-Four were briefly reviewed.