OBJECTIVE: To explore the genetic background and clinical phenotypes of multiple idiopathic cervical root resorption (MICRR) in a Chinese family.
METHODS: The proband and his three family members were clinically examined and had radiographs taken with a radiovisiography (RVG) system and CBCT to define the diagnosis of MICRR. Genomic DNA (gDNA) was extracted from peripheral blood samples of the patient, his father, mother and younger sister for whole exome sequencing (WES). The pathogenicity of rare variants with minor allele frequency (MAF) less than 0.005 were analysed following possible inheritance patterns, predicted results from 12 software programs, the American College of Medical Genetics (ACMG) 2015 criteria, and information from ClinVar, OMIM and HGMD databases as well as gene function.
RESULTS: The proband presented the typical MICRR phenotypes such as thin cervical pulp wall and apple core-like lesions in radiographs. Following the recessive inheritance pattern, WES analysis identified SHROOM2, SYTL5, MAGED1 and FLNA with a higher chance of causing MICRR. Four genes with compound heterozygous variants and another 27 genes with de novo variants either in autosomal-dominant or autosomal-recessive pattern were also found to have the potential pathogenicity.
CONCLUSIONS: A total of 35 novel potential pathogenic genes were found to be associated with MICRR from a Chinese family through WES. The new genetic background of MICRR may be helpful for clinical and molecular diagnosis.

BACKGROUND: Multiple idiopathic cervical root resorption (MICRR) is a disease with an unknown etiology that causes invasive cervical root resorption in multiple teeth. Although previous MICRR genomic studies have identified candidate gene variants, the etiology of the condition remains poorly understood. In the present study, we investigated the genetic causality of MICRR to explore candidate variants.
METHODS: Saliva samples from a family containing 2 affected and two unaffected subjects with the dominant transmission of MICRR were subjected to whole-exome sequencing.
RESULTS: As a result, we identified novel candidate variants of 10 genes. Each variant was confirmed by Sanger sequencing. Among them, the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP) guidelines classified doublecortin domain containing 1 (c.1099 C > T) and β-defensin 114 (c.189 T > G) as \"pathogenic,\" and solute carrier family 45 member 2 (c.152_153del) as \"likely pathogenic.\"
CONCLUSIONS: These results provide new insight to help clarify the pathogenesis of MICRR, and the variants could be applied for further investigation to understand invasive cervical root resorption.

Multiple idiopathic cervical root resorption (MICRR) is a rare condition. The etiology is unknown and occurs spontaneously in healthy controls in the absence of local, systemic, or any other plausible cause. The teeth themselves appear clinically normal. The pattern of resorption begins in cementoenamel junction and can progress rapidly over a short time. It is a debilitating condition which often leads to extraction of all the involved teeth. This article describes a case of MICRR over a period of 7 years with emphasis on the history, clinical/histological findings, cone beam computed tomographic examination, therapeutic intervention as well as the final prosthodontic rehabilitation with implants.

Multiple idiopathic cervical root resorption is an aggressive form of external root resorption that occurs at the cementoenamel junction and can affect multiple teeth (a minimum of 3) throughout the entire dentition. Most of the individuals affected are healthy with noncontributory medical histories. The resorption is usually detected as an incidental finding on radiographs or during dental examination. This case report describes an adult female with multiple cervical root resorptions who had been treated with chemotherapy for ovarian cancer at 16 years old. Nine years later, a total of 12 teeth were diagnosed with cervical root resorption. All of the known causative factors for external cervical resorption were discarded. To our knowledge, this is the first case reported of multiple cervical root resorption related to chemotherapy.

Multiple idiopathic cervical root resorptions are a rare finding. The diagnosis is perplexing, and treatment is a challenge. It is a debilitating condition that often leads to extraction of all the involved teeth. Various theories have been given for explanation of the disease entity; however, the etiology remains elusive. This report describes a case of an 18-year-old man with idiopathic cervical resorption that progressed aggressively and involved 20 teeth. The medical history of hepatitis B virus infection made this case unique in the literature. The mechanism of increased osteoclastic activity in patients with hepatitis B virus infection is discussed as a predisposing factor for the development of root resorption.