A delayed diagnosis of Pallister-Hall syndrome in an adult male following the incidental detection of a hypothalamic hamartoma

Pallister-Hall syndrome, GLI3, and kidney malformation

Pallister-Hall syndrome (PHS) is a rare autosomal dominant disease diagnosed by the presence of hypothalamic hamartoma, mesoaxial polydactyly and a truncating variant in the middle third of the GLI-Kruppel family member 3 (GLI3) gene. PHS may also include a wide range of clinical phenotypes affecting multiple organ systems including congenital anomalies of the kidney and urinary tract (CAKUT). The observed clinical phenotypes are consistent with the essential role of GLI3, a transcriptional effector in the hedgehog (Hh) signaling pathway, in organogenesis. However, the mechanisms by which truncation of GLI3 in PHS results in such a variety of clinical phenotypes with variable severity, even within the same organ, remain unclear. In this study we focus on presentation of CAKUT in PHS. A systematic analysis of reported PHS patients (n = 78) revealed a prevalence of 26.9% (21/78) of CAKUT. Hypoplasia (± dysplasia) and agenesis were the two main types of CAKUT; bilateral and unilateral CAKUT were reported with equal frequency. Examination of clinical phenotypes with CAKUT revealed a significant association between CAKUT and craniofacial defects, bifid epiglottis and a Disorder of Sex Development, specifically affecting external genitalia. Lastly, we determined that PHS patients with CAKUT predominately had substitution type variants (as opposed to deletion type variants in non-CAKUT PHS patients) in the middle third of the GLI3 gene. These results provide a foundation for future work aimed at uncovering the molecular mechanisms by which variant GLI3 result in the wide range and severity of clinical features observed in PHS.

Pallister-Hall syndrome diagnosed in a young man after an acute adrenal crisis

Pallister-Hall syndrome (PHS) is a very rare genetic disorder. The diagnosis is usually suspected at the young age when a hypothalamic hamartoma is associated with polydactyly. Endocrine manifestations are mostly related to hypothalamic hamartoma and rarely reveal the disease. We report the case of an 18-year-old young man in whom the diagnosis of PHS was delayed until his hospitalization in the endocrinology department for acute adrenal insufficiency.

Case Report: Whole-Exome Sequencing of Hypothalamic Hamartoma From an Infant With Pallister-Hall Syndrome Revealed Novel de novo Mutation in the GLI3

Background: GLI-Kruppel family member 3 (GLI3), a zinc finger transcription factor of the sonic hedgehog pathway, is essential for organ development. Mutations in GLI3 cause several congenital conditions, including Pallister-Hall syndrome (PHS), which is characterized by polydactyly and hypothalamic hamartoma. Most patients are diagnosed soon after birth, and surgical removal of hypothalamic hamartoma in the very young is rarely performed because of associated risks.

Case presentation: A 7-month-old boy with PHS features, including a suprasellar lesion, bifid epiglottis, tracheal diverticulum, laryngomalacia, left-handed polydactyly and syndactyly, and omental hernia was referred to our service. His suprasellar lesion was partially removed, and whole-exome sequencing was applied to the resected tumor, his peripheral blood, and blood from his parents. Histopathology confirmed the diagnosis of hypothalamic hamartoma, and molecular profiling revealed a likely pathogenic de novo variant, c.2331C>G (p. H777Q), in GLI3. Magnetic resonance imaging follow-up 1 year later showed some residual tumor, and the patient experienced normal development post operation.

Conclusions: We presented a case of PHS that carries a novel GLI3 variant. Hypothalamic hamartoma showed a distinct genetic landscape from germline DNA. These data offer insights into the underlying etiology of hypothalamic hamartoma development in patients with PHS.