Molecular analysis of MKRN3 gene in Turkish girls with sporadic and familial idiopathic central precocious puberty.

OBJECTIVES: Central precocious puberty (CPP) develops as a result of early stimulation of the hypothalamic-pituitary-gonadal (HPG) axis. The loss-of-function mutations in the Makorin-ring-finger3 (MKRN3) gene appear to be the most common molecular cause of familial CPP. We aimed to identify MKRN3 gene mutations in our CPP cohort and to investigate the frequency of MKRN3 mutations. METHODS: 102 patients with CPP included. 53 of them had family history of CPP in the first and/or second-degree relatives. MKRN3 gene was analyzed by next-generation sequencing. RESULTS: Possible pathogenic variants were found in 2/53 patients with family history of CPP (3.8%) and 1/49 patient without family history (2%). A novel heterozygous c.1A>G (p.Met1Val) mutation, a novel heterozygous c.683_684delCA (p.Ser228*) and a previously reported c.482dupC (Ala162Glyfs*) frameshift variations were detected. The two novel variants are predicted to be pathogenic in silico analyses. CONCLUSIONS: In our cohort, possible pathogenic variants in MKRN3 gene were detected in 2.9% of the total cohort, 3.8% of the familial and 2% of the nonfamilial cases, slightly lower than that reported in the literature. Two novel variants detected contribute to the molecular repertoire of MKRN3 defects in CPP. Classical pattern of paternal inheritance has been demonstrated in all three cases. However, the father of the patient 3 did not have history of CPP suggesting that the father inherited this variant from his mother and had phenotype skipping. Therefore, we emphasize that the absence of history of CPP in the father does not exclude the possibility of a MKRN3 mutation.

Long-Term Efficacy of T3 Analogue Triac in Children and Adults With MCT8 Deficiency: A Real-Life Retrospective Cohort Study.

CONTEXT: Patients with mutations in thyroid hormone transporter MCT8 have developmental delay and chronic thyrotoxicosis associated with being underweight and having cardiovascular dysfunction. OBJECTIVE: Our previous trial showed improvement of key clinical and biochemical features during 1-year treatment with the T3 analogue Triac, but long-term follow-up data are needed. METHODS: In this real-life retrospective cohort study, we investigated the efficacy of Triac in MCT8-deficient patients in 33 sites. The primary endpoint was change in serum T3 concentrations from baseline to last available measurement. Secondary endpoints were changes in other thyroid parameters, anthropometric parameters, heart rate, and biochemical markers of thyroid hormone action. RESULTS: From October 15, 2014 to January 1, 2021, 67 patients (median baseline age 4.6 years; range, 0.5-66) were treated up to 6 years (median 2.2 years; range, 0.2-6.2). Mean T3 concentrations decreased from 4.58 (SD 1.11) to 1.66 (0.69) nmol/L (mean decrease 2.92 nmol/L; 95% CI, 2.61-3.23; P < 0.0001; target 1.4-2.5 nmol/L). Body-weight-for-age exceeded that of untreated historical controls (mean difference 0.72 SD; 95% CI, 0.36-1.09; P = 0.0002). Heart-rate-for-age decreased (mean difference 0.64 SD; 95% CI, 0.29-0.98; P = 0.0005). SHBG concentrations decreased from 245 (99) to 209 (92) nmol/L (mean decrease 36 nmol/L; 95% CI, 16-57; P = 0.0008). Mean creatinine concentrations increased from 32 (11) to 39 (13) µmol/L (mean increase 7 µmol/L; 95% CI, 6-9; P < 0.0001). Mean creatine kinase concentrations did not significantly change. No drug-related severe adverse events were reported. CONCLUSIONS: Key features were sustainably alleviated in patients with MCT8 deficiency across all ages, highlighting the real-life potential of Triac for MCT8 deficiency.