Noonan syndrome-like disorder with loose anagen hair: a second case with neuroblastoma.

Noonan-like syndrome with loose anagen hair (NSLH), also known as Mazzanti syndrome, is a RASopathy characterized by craniofacial features resembling Noonan syndrome, cardiac defects, cognitive deficits and behavioral issues, reduced growth generally associated with GH deficit, darkly pigmented skin, and an unique combination of ectodermal anomalies. Virtually all cases of NSLH are caused by an invariant and functionally unique mutation in SHOC2 (c.4A>G, p.Ser2Gly). Here, we report on a child with molecularly confirmed NSLH who developed a neuroblastoma, first suspected at the age 3 months by abdominal ultrasound examination. Based on this finding, scanning of the SHOC2 coding sequence encompassing the c.4A>G change was performed on selected pediatric cohorts of malignancies documented to occur in RASopathies (i.e., neuroblastoma, brain tumors, rhabdomyosarcoma, acute lymphoblastic, and myeloid leukemia), but failed to identify a functionally relevant cancer-associated variant. While these results do not support a major role of somatic SHOC2 mutations in these pediatric cancers, this second instance of neuroblastoma in NSLAH suggests a possible predisposition to this malignancy in subjects heterozygous for the c.4A>G SHOC2 mutation.

Focal dermal hypoplasia (Goltz-Gorlin syndrome): a new case with a novel variant in the PORCN gene (c.1250T>C:p.F417S) and unusual spinal anomaly.

Focal dermal hypoplasia (FDH; Goltz-Gorlin syndrome; OMIM 305600) is a disorder that features involvement of the skin, skeletal system, and eyes. It is caused by loss-of-function mutations in the PORCN gene. We report a young girl with FDH, microphthalmos associated with colobomatous orbital cyst, dural ectasia and cystic malformation of the spinal cord, and a de novo variant in PORCN. This association has not been previously reported, and based on these observations the phenotypic spectrum of FDH might be broader than previously appreciated. It would be prudent to alter the suggested surveillance for this rare disorder.

Heme oxygenase expression and activity in immortalized hypothalamic neurons GT1-7.

Heme oxygenase (HO), the main enzyme deputed to heme metabolism, has been identified as two main isoforms called HO-1 and HO-2. HO-1 is inducible and plays a main role in the cellular oxidant/antioxidant balance whereas HO-2 is constitutive and involved in the physiological metabolism of heme. However, it is noteworthy to mention that HO contribute to the regulation of the hypothalamic release of neuropeptides such as corticotrophin-releasing hormone and arginine-vasopressin and could modulate the pulsatile release of gonadotropin releasing hormone (GnRH). GT1-7 cells are immortalized hypothalamic neurons and a valuable tool to evaluate hypothalamic neuroendocrine control of reproduction. The aim of this work was to investigate and characterize the presence of HO isoforms in the GT1-7 hypothalamic neurons. Hemin, a well-known inducer of HO-1, significantly increased HO activity, whereas dexamethasone did not modify HO-2 activity. Moreover, hemin and DEX, in combination, did not have any additive effect on HO activity in GT1-7 neurons. Furthermore, basal HO-1 immunoreactivity identified in GT1-7 cells, was significantly up-regulated by hemin. Conversely, no HO-2 immunoreactivity was detected. Taken together, these results suggest the presence of functional HO-1 in GT1-7 immortalized hypothalamic neurons and open new avenues about the use of this cell line for the study of HO modulation of GnRH secretion and reproduction.

Heme oxygenase-derived carbon monoxide modulates gonadotropin-releasing hormone release in immortalized hypothalamic neurons.

Heme oxygenase (HO), the main enzyme deputed to heme metabolism, has been identified as two main isoforms called HO-1 and HO-2 both present in the central nervous system. Heme oxygenase has been shown to regulate the hypothalamic release of neuropeptides such as corticotrophin-releasing hormone and arginin-vasopressin. The aim of this study was to investigate and further characterize the presence of HO in gonadotropin-releasing hormone (GnRH) secreting hypothalamic neurons, GT1-7 and the role of HO by-products on GnRH secretion. The pulsatile release of GnRH from scattered hypothalamic neurons is the key regulator of mammalian fertility in the central nervous system. GT1-7 cells are immortalized hypothalamic neurons, characterized by spontaneous electrical activity and pulsatile GnRH release, resembling the central control pathway of the hypothalamic pituitary gonadal axis (HPG) in mammals. Hemin, the substrate of HO, significantly stimulated HO activity in static cultures, causing a rapid increase in GnRH release. Neither biliverdin nor bilirubin were able to mimic this rapid stimulatory effect, which was instead caused by carbon monoxide. Evidence of a possible involvement of prostaglandin E(2) in the HO by-product modulated GnRH secretion was reported. The hemin-evoked effect on GT1-7 neurons suggests a direct activity of HO by-products on the hypothalamic neuropeptide secretion, and claims for a possible role of CO in both the modulation of gonadotropin secretion and crosstalk among HPG and stress axis within the mammalian hypothalamus.