Romina P Grinspon, Carolina Habib, Patricia Bedecarrás, Silvia Gottlieb and Rodolfo A Rey
Compensatory hypertrophy has been classically described in patients with monorchidism. However, it remains unclear whether there is a functional compensatory activity of the different cell populations. Our aim was to assess the functional capacity of the solitary testis in monorchid males from infancy through puberty in order to determine whether the remaining gonad is capable of compensating the functional activity of Sertoli and Leydig cells of the absent gonad.
In a retrospective, cross-sectional, analytical study performed at a tertiary paediatric public hospital, we included 89 boys with monorchidism and 358 healthy controls, aged 6 months–18 years. Testicular volume and circulating levels of reproductive hormones were compared between patients with monorchidism and normal boys. Serum anti-Müllerian hormone (AMH) and FSH were used as biomarkers of the functional mass of prepubertal Sertoli cells, whereas serum testosterone and LH were used as biomarkers of Leydig cells.
In the vast majority of the cases, the testicular volume of monorchid boys was smaller than the sum of the volume of both testes of healthy controls. Serum AMH was lower and FSH was higher in patients with monorchidism than in controls aged <3 and >13 years. Serum testosterone and LH did not differ significantly between patients and controls.
In boys and adolescents with monorchidism, there is a dissociated capacity of the remaining testis to compensate for the absence of the other gonad: while Leydig cell function is largely compensated, Sertoli cell proliferation and function was lower than in controls.
Ana Claudia Keselman, Ayelen Martin, Paula Alejandra Scaglia, Nora María Sanguineti, Romina Armando, Mariana Gutiérrez, Débora Braslavsky, María Gabriela Ballerini, María Gabriela Ropelato, Laura Ramirez, Estefanía Landi, Sabina Domené, Julia F Castro, Hamilton Cassinelli, Bárbara Casali, Graciela del Rey, Ángel Campos Barros, Julián Nevado Blanco, Horacio Domené, Héctor Jasper, Claudia Arberas, Rodolfo A Rey, Pablo Lapunzina-Badía, Ignacio Bergadá and Patricia A Pennisi
IGF1 is a key factor in fetal and postnatal growth. To date, only three homozygous IGF1 gene defects leading to complete or partial loss of IGF1 activity have been reported in three short patients born small for gestational age. We describe the fourth patient with severe short stature presenting a novel homozygous IGF1 gene mutation.
We report a boy born from consanguineous parents at 40 weeks of gestational age with intrauterine growth restriction and severe postnatal growth failure. Physical examination revealed proportionate short stature, microcephaly, facial dysmorphism, bilateral sensorineural deafness and mild global developmental delay. Basal growth hormone (GH) fluctuated from 0.2 to 29 ng/mL, while IGF1 levels ranged from −1.15 to 2.95 SDS. IGFBP3 was normal-high. SNP array delimited chromosomal regions of homozygosity, including 12q23.2 where IGF1 is located. IGF1 screening by HRM revealed a homozygous missense variant NM_000618.4(IGF1):c.322T>C, p.(Tyr108His). The change of the highly conserved Tyr60 in the mature IGF1 peptide was consistently predicted as pathogenic by multiple bioinformatic tools. Tyr60 has been described to be critical for IGF1 interaction with type 1 IGF receptor (IGF1R). In vitro, HEK293T cells showed a marked reduction of IGF1R phosphorylation after stimulation with serum from the patient as compared to sera from age-matched controls. Mutant IGF1 was also less efficient in inducing cell growth.
The present report broadens the spectrum of clinical and biochemical presentation of homozygous IGF1 defects and underscores the variability these patients may present depending on the IGF/IGF1R pathway activity.