Hereditary leiomyomatosis and renal cell cancer syndrome (HLRCC): Genotype and phenotype characteristics in a cohort of 197 patients

1580 Background: HLRCC is a hereditary condition with autosomal dominant inheritance due to germline mutations in the fumarate-hydratase gene ( FH). It is characterized by skin leiomyomas (SLM) in 48-84% of individuals, uterine leiomyomas (ULM) in 30-72%, renal cysts (RCy) and renal cell cancer (RCC) in 15-34%. We aimed to describe the genetics, the clinical features and the potential genotype-phenotype associations in the largest cohort of FH mutation carriers from Spain. Methods: We performed a multicenter, observational, retrospective study of individuals with genetic or clinical diagnosis of HLRCC. We collected clinical information from medical records. We analyzed genetic variants and looked for genotype-phenotype associations. Statistical analyses were performed by IBM-SPSS Statistics-v.22. Results: We included 197 individuals (113 women, 84 men), 74 index cases and 123 relatives. Twenty-seven different variants were detected, 26 pathogenic (12 missense, 5 frameshift, 4 large-deletions, 3 splice-site and 2 nonsense) and 1 variant of unknown significance (missense). Of 182 patients with full skin examination, 64.8% presented SLM (median age 36 years; range 8-85). ULM were diagnosed in 90.3% of 103 women with gynecologic exam (median age 30 years; range 17- 55). Hysterectomy was performed in 62.9% (median age 34 years; range 21-54). Of 153 patients with radiological records, 37.3 % presented RCy. Nineteen patients (10.9%) presented RCC, 11 males and 8 females (median age 37 years; range 10-67). The histological diagnoses were: 14 papillary, of which 10 were type 2; 3 clear cell carcinoma and 2 unclassified carcinoma. Six tumors had stage I, 2 stage II, 3 stage III, 4 stage IV, and 4 not available. The median overall survival among patients at stages 3-4 was 2.9 years [1.3-4.5]. Patients with missense pathogenic variants showed higher risk of developing SLM (p = 0.043) and ULM (p = 0.002) than those with loss of function variants. Conclusions: In our cohort, the frequency of RCC (10.9%) is lower than that published in cohorts of similar sample size. The most frequent histology was the papillary type-2; however, other histological patterns do not exclude HLRCC. Individuals with missense pathogenic variants show higher incidence of SLM and ULM.