High-throughput splicing assays identify missense and silent splice-disruptive POU1F1 variants underlying pituitary hormone deficiency.

Pituitary hormone deficiency occurs in ∼1:4,000 live births. Approximately 3% of the cases are due to mutations in the alpha isoform of POU1F1, a pituitary-specific transcriptional activator. We found four separate heterozygous missense variants in unrelated individuals with hypopituitarism that were predicted to affect a minor isoform, POU1F1 beta, which can act as a transcriptional repressor. These variants retain repressor activity, but they shift splicing to favor the expression of the beta isoform, resulting in dominant-negative loss of function. Using a high-throughput splicing reporter assay, we tested 1,070 single-nucleotide variants in POU1F1. We identified 96 splice-disruptive variants, including 14 synonymous variants. In separate cohorts, we found two additional synonymous variants nominated by this screen that co-segregate with hypopituitarism. This study underlines the importance of evaluating the impact of variants on splicing and provides a catalog for interpretation of variants of unknown significance in POU1F1.

Phenotypic Variability in a Family with Acrodysostosis Type 2 Caused by a Novel PDE4D Mutation Affecting the Serine Target of Protein Kinase-A Phosphorylation.

Acrodysostosis is a very rare congenital multisystem condition characterized by skeletal dysplasia with severe brachydactyly, midfacial hypoplasia, and short stature, varying degrees of intellectual disability, and possible resistance to multiple G protein-coupled receptor signalling hormones. Two distinct subtypes are differentiated: acrodysostosis type 1 resulting from defects in protein kinase type 1-α regulatory subunit and acrodysostosis type 2 caused by mutations in phosphodiesterase 4D (PDE4D). Most cases are sporadic. We report on a rare multigenerational familial case of acrodysostosis type 2 due to a novel autosomal dominantly inherited PDE4D mutation. A 3.5-year-old boy presented with short stature, midfacial hypoplasia, severe brachydactyly, developmental delay, and behavioural problems. Laboratory investigations revealed mild thyrotropin resistance. His mother shared some characteristic features, such as midfacial hypoplasia and severe brachydactyly, but did not show short stature, intellectual disability or hormonal resistance. Genetic analysis identified the identical, novel heterozygous missense mutation of the PDE4D gene c.569C>T (p.Ser190Phe) in both patients. This case illustrates the significant phenotypic variability of acrodysostosis even within one family with identical mutations. Hence, a specific clinical diagnosis of acrodysostosis remains challenging because of great interindividual variability and a substantial overlap of the two subtypes as well as with other related Gsα-cAMP-signalling-linked disorders.

How early can one diagnose Cushing's disease? An early diagnosis in a case of prepubertal Cushing's disease.

BACKGROUND: Cushing's disease is very rare in children, and the diagnosis is frequently delayed by several years. OBJECTIVE: We report a case of prepubertal Cushing's disease with a medical history of only 9 months. This case illustrates the difficulties involved in diagnosing children at the early stage of the disease. CASE PRESENTATION: An 8-year-old prepubertal boy presented with rapid weight gain accompanied by a decreasing growth velocity and hirsutism. Thyroid function tests and growth factor levels were normal, thus excluding hypothyroidism and growth hormone deficiency. Cushing's syndrome was confirmed by elevated 24-h urinary free cortisol levels, increased diurnal cortisol levels, and a lack of cortisol suppression in the low-dose dexamethasone suppression test. Further tests to investigate the source of the hypercortisolism showed the following results: Basal morning adrenocorticotropic hormone (ACTH) was normal. The high-dose dexamethasone suppression test led to a 51% decrease in cortisol level. In the corticotropin-releasing hormone (CRH) test, ACTH and cortisol increased only by 28%. Repeated magnetic resonance imaging (MRI) finally revealed a microadenoma in the anterior pituitary, thus establishng the diagnosis of Cushing's disease. Upon diagnosis, the patient underwent transsphenoidal surgery. Histological analysis confirmed an ACTH-secreting pituitary adenoma. CONCLUSION: This case illustrates the difficulties associated with the clinical, biochemical, and radiological diagnoses of Cushing's disease in children. Early diagnosis remains a challenge because test results often do not match standard diagnostic criteria.