In approximately half of congenital hypogonadotropic hypogonadism (cHH) patients, the genetic cause remains unidentified. Since the lack of certain miRNAs in animal models has led to cHH, we sequenced human miRNAs predicted to regulate cHH-related genes (MIR7-3, MIR141, MIR429 and MIR200A-C) in 24 cHH patients with Sanger sequencing. A heterozygous variant in MIR200A (rs202051309; general population frequency of 0.02) was found in one patient. Our results suggest that mutations in the studied miRNAs are unlikely causes of cHH. However, the complex interplay between miRNAs and their target genes in these diseases requires further investigations.
Anna-Pauliina Iivonen, Johanna Känsäkoski, Kirsi Vaaralahti and Taneli Raivio
Anna-Pauliina Iivonen, Johanna Känsäkoski, Atte Karppinen, Leena Kivipelto, Camilla Schalin-Jäntti, Auli Karhu and Taneli Raivio
Recently, mutations in KCNQ1, a potassium channel gene usually linked to long QT syndrome, were reported to cause maternally inherited gingival fibromatosis and growth hormone deficiency (GHD). Expression of the mutated KCNQ1 with the auxiliary potassium channel subunit KCNE2 was shown to reduce pituitary hormone secretion in functional experiments. Here, we investigated if germline mutations in KCNQ1 and KCNE2 were present in patients with somatotropinomas, which represent a model of growth hormone excess.
Design and methods
KCNQ1 and KCNE2 were screened for germline mutations in 53 patients with acromegaly by Sanger sequencing. Effects of the variants were predicted by in silico tools.
Only deep intronic and synonymous polymorphisms were detected in KCNQ1. These findings were likely insignificant based on in silico predictions and the variants’ frequencies in the general population. In KCNE2, a heterozygous c.22A>G, p.(Thr8Ala) mutation with unknown significance was found in three patients. It was present in the database controls with a frequency of 0.0038.
KCNQ1 or KCNE2 mutations do not appear to account for somatotropinoma formation, although larger patient series are needed to validate the findings.