# Clinical characteristics, genetic spectrum and therapeutic effects of 51 male patients with idiopathic hypogonadotropic hypogonadism from southern China

## TL;DR

This study examines the clinical and genetic features of 51 male IHH patients in southern China and evaluates treatment outcomes.

## Contribution

The study expands the genetic spectrum of IHH and identifies clinical markers for early diagnosis and differential diagnosis.

## Key findings

- FGFR1 is the most common causative gene in southern Chinese male IHH patients.
- ANOS1 and CHD7 variants show distinct clinical and biochemical profiles.
- Treatment significantly improves penile length and hormone levels in IHH patients.

## Abstract

Idiopathic hypogonadotropic hypogonadism (IHH) is a set of rare diseases characterized by abnormal sexual development with clinical heterogeneity and genotypic complexity. This study aims to investigate the phenotypic and genotypic characteristics of male IHH in southern China, and evaluate the therapeutic effects of current treatments.

Fifty-one male IHH patients from southern China were enrolled in this study. Their clinical, imaging, hormonal and genetic findings were analyzed retrospectively.

In this study, the most common causative gene of IHH was FGFR1 (45.10%), followed by ANOS1 (21.57%) and CHD7 (17.65%). Forty-five different variants, including 22 known and 23 novel variants, were found. The mean age at diagnosis was 7.84 ± 5.89 years, the most common clinical phenotype was micropenis (98.04%), the most frequent imaging feature was abnormal ultrasound of sexual glands (86.84%), and the most representative biochemical manifestations were low basal luteinizing hormone (LH) and testosterone (98.04% and 100.00%, respectively). Age-phenotype and genotype-phenotype correlations were observed in this cohort. The penile length, testicular volume, basal testosterone, and the proportion of patients with low basal inhibin B were associated with age. Most patients with ANOS1 variant had a family history, impaired olfactory function, and much lower basal anti-mullerian hormone (AMH), whereas patients with CHD7 variant were younger, presented CHARGE phenotypes, and had higher basal follicle-stimulating hormone (FSH) and LH. Moreover, 34 patients were treated with different strategies for 2.75 ± 1.82 years. After treatment, the penile length, and the levels of FSH, LH and testosterone increased significantly.

Our study adds 51 southern Chinese male patients, and expands the mutational spectrum for IHH. Our cohort suggests that a combination of clinical, biochemical and genetic criteria will facilitate early diagnosis. Our work also highlights the differentially diagnostic values of family history, impaired olfactory function, CHARGE features, and basal AMH, FSH and LH in distinguishing different molecular bases of IHH.

The online version contains supplementary material available at 10.1186/s13023-025-04050-2.