Treatment with TRIAC in pediatric patients with MCT8

Monocarboxylate transporters (MCTs) allow the cellular entry of thyroid hormones, especially into the central nervous system (CNS), where they are crucial for neurodevelopment. MCT8 deficiency results in the combination of hypothyroidism in the CNS and peripheral hyperthyroidism, characterized by elevated T3 levels. The only treatment currently available is 3,3',5-triiodothyroacetic acid (TRIAC), a thyroid hormone analogue aimed at improving peripheral thyrotoxicosis and preventing the progression of neurological impairment. Here we assess the clinical, imaging, biochemical, and genetic characteristics of 4 patients with MCT8 deficiency who have received TRIAC to date, the doses used, and the response to treatment.

Gonadal tumor development in 46,XX disorders of gonadal development

BACKGROUND

Differences/disorders of sex development (DSD) are congenital conditions in which the development of chromosomal, gonadal, or anatomical sex is atypical.

OBJECTIVE

The aim of this study is to report the histological characteristics and immunoexpression patterns of gonadal parenchyma in patients with 46,XX testicular and ovotesticular DSD, with a focus on the detection of germ cell malignancies.

DESIGN

Inclusion criteria were SRY-negative 46,XX testicular and ovotesticular DSD with available samples from gonadal biopsy or gonadectomy for the review of histological findings. Gonadal histology was assessed on hematoxylin and eosin-stained sections and immunohistochemical analysis. Histopathological criteria from the last World Health Organization classification of urogenital tumors were used to identify undifferentiated gonadal tissue, gonadoblastoma, and dysgerminoma.

RESULTS

Median age at first histological evaluation of gonadal samples was 1.46 years (range: 0.16-16 years). Totally 15 patients were classified as ovotesticular and only 1 as testicular DSD. Most individuals had bilateral ovotestes (12/15). No histological alterations were found in the ovarian parenchyma, while signs of dysgenesis were seen in all cases of testicular parenchyma. In 4/15 ovotesticular DSD, a prepubertal biopsy failed to identify ovarian parenchyma. We detected early prepubertal preinvasive and invasive malignancies in this cohort (five patients had undifferentiated gonadal tissue, five gonadoblastoma, and one dysgerminoma).

CONCLUSION

46,XX disorders of gonadal development are historically considered at a low risk for germ cell cancer, and the need for assessment of gonadal histology has been questioned. The finding of early germ cell malignancies in our cohort brings awareness and needs further research.

Comprehensive Identification of Pathogenic Gene Variants in Patients With Neuroendocrine Disorders

PURPOSE

Congenital hypopituitarism (CH) can present in isolation or with other birth defects. Mutations in multiple genes can cause CH, and the use of a genetic screening panel could establish the prevalence of mutations in known and candidate genes for this disorder. It could also increase the proportion of patients that receive a genetic diagnosis.

METHODS

We conducted target panel genetic screening using single-molecule molecular inversion probes sequencing to assess the frequency of mutations in known hypopituitarism genes and new candidates in Argentina. We captured genomic deoxyribonucleic acid from 170 pediatric patients with CH, either alone or with other abnormalities. We performed promoter activation assays to test the functional effects of patient variants in LHX3 and LHX4.

RESULTS

We found variants classified as pathogenic, likely pathogenic, or with uncertain significance in 15.3% of cases. These variants were identified in known CH causative genes (LHX3, LHX4, GLI2, OTX2, HESX1), in less frequently reported genes (FOXA2, BMP4, FGFR1, PROKR2, PNPLA6) and in new candidate genes (BMP2, HMGA2, HNF1A, NKX2-1).

CONCLUSION

In this work, we report the prevalence of mutations in known CH genes in Argentina and provide evidence for new candidate genes. We show that CH is a genetically heterogeneous disease with high phenotypic variation and incomplete penetrance, and our results support the need for further gene discovery for CH. Identifying population-specific pathogenic variants will improve the capacity of genetic data to predict eventual clinical outcomes.

Accelerated Pubertal Tempo in a 46,XY Aromatase-Deficient Patient

BACKGROUND

Aromatase deficiency is a rare autosomal recessive disorder. 46,XY-affected patients often remain undiagnosed until late puberty. Only 2 pediatric cases have been reported. Data on pubertal development in affected males are scarce.

AIM

To report the clinical phenotype and hormonal studies of an aromatase-deficient boy during the prepubertal and early pubertal period.

RESULTS

The patient was the older brother of a 46,XX girl with aromatase deficiency. Molecular analysis revealed a previously reported homozygous mutation (Arg192Cys) in the CYP19A1 gene. Pubertal onset was at 9.8 years. At 11.3 years of age, signs of rapidly progressive puberty were seen. Laboratory tests revealed normal pubertal basal and GnRH-stimulated gonadotropin levels, normal Sertoli cell markers, and increased testosterone. The prepubertal lumbar spine bone mineral density (BMD) was normal but pubertal bone mineral accrual was incomplete, leading to osteopenia.

CONCLUSION

Estrogen restraint on gonadotropin secretion has been demonstrated in animal and human models. Interestingly, our patient presented with accelerated puberty and apparently normal pituitary gonadal function. These findings suggest that aromatase activity may be required to define pubertal progression in boys. Estrogen deficiency due to aromatase deficiency is responsible for insufficient bone mineral accrual during puberty.