Lhermitte-Duclos disease caused by a novel germline PTEN mutation R173P in a patient presenting with psychosis

Systemic lupus erythematosus in a girl with PTEN variant and transaldolase deficiency: a novel phenotype

Genetic defect of phosphatase and tensin homolog (PTEN) gene might play a role in B cell hyperactivity and result in the development of systemic lupus erythematosus (SLE), while transaldolase deficiency has a spectrum of clinical features including autoimmune endocrinopathy. Herein, we identified a novel phenotype in a girl presenting with clinical and laboratory findings consistent with SLE. Exome sequencing identified pathogenic heterozygous variant in PTEN gene (NM_000314: exon 6: c.518G > C: p. R173P) and homozygous variant in TALDO1 gene (NM_006755: exon 6: c.793C del: p. Q265f). Our report highlights the association of PTEN mutation and autoimmunity and the possibility that transaldolase deficiency may be indirectly involved in the development of SLE.

[Hereditary tumor syndromes in neuropathology]

Neoplasms in the central (CNS) and peripheral nervous system (PNS) in hereditary tumor syndromes play an important role in the neuropathological diagnostics. The benign and malignant PNS and CNS tumors that occur in the frequent neurofibromatosis type 1 (NF1) and type 2 (NF2) often represent essential factors for the course of the disease in those affected. Furthermore, certain clinical constellations (e.g. bilateral schwannomas of the auditory nerve, schwannomas at a young age and multiple meningiomas) can be important indications for a previously undiagnosed hereditary tumor disease. Other tumors occur practically regularly in association with certain germline defects, e.g. subependymal giant cell astrocytoma (SEGA) in tuberous sclerosis and dysplastic gangliocytoma of the cerebellum in Cowden's syndrome and can be indications in the diagnostics for an extended genetic counselling. This is not only important because many germline defects are based on new mutations, but also for the now established targeted therapy of certain tumors, e.g. inhibition of the mammalian target of rapamycin (mTOR) signaling pathway using temsirolimus for SEGA. Furthermore, knowledge about the possible constellations of genetic mosaics in hereditary tumor syndromes with the resulting (incomplete) syndrome manifestations is useful. This review article summarizes the most important hereditary tumor syndromes with involvement of the PNS and CNS.

Phosphatase and Tensin Homologue: Novel Regulation by Developmental Signaling

Phosphatase and tensin homologue (PTEN) is a critical cell endogenous inhibitor of phosphoinositide signaling in mammalian cells. PTEN dephosphorylates phosphoinositide trisphosphate (PIP3), and by so doing PTEN has the function of negative regulation of Akt, thereby inhibiting this key intracellular signal transduction pathway. In numerous cell types, PTEN loss-of-function mutations result in unopposed Akt signaling, producing numerous effects on cells. Numerous reports exist regarding mutations in PTEN leading to unregulated Akt and human disease, most notably cancer. However, less is commonly known about nonmutational regulation of PTEN. This review focuses on an emerging literature on the regulation of PTEN at the transcriptional, posttranscriptional, translational, and posttranslational levels. Specifically, a focus is placed on the role developmental signaling pathways play in PTEN regulation; this includes insulin-like growth factor, NOTCH, transforming growth factor, bone morphogenetic protein, wnt, and hedgehog signaling. The regulation of PTEN by developmental mediators affects critical biological processes including neuronal and organ development, stem cell maintenance, cell cycle regulation, inflammation, response to hypoxia, repair and recovery, and cell death and survival. Perturbations of PTEN regulation consequently lead to human diseases such as cancer, chronic inflammatory syndromes, developmental abnormalities, diabetes, and neurodegeneration.

PTEN inactivation by germline/somatic c.950_953delTACT mutation in patients with Lhermitte-Duclos disease manifesting progressive phenotypes

Lhermitte-Duclos disease (LDD), a neurological manifestation of Cowden syndrome (CS), is a rare and benign cerebellar disorder, featured by dysplastic cerebellar ganglion cells which replace granular and Purkinje cells. Phosphatase and Tensin Homolog (PTEN) is confirmed as the susceptibility gene for CS which represents the most complex features and is not easily recognizable. We reported two index patients with LDD diagnosed either in an isolated form or coexist with CS. These two patients displayed progressive though comparable phenotypes and were found to carry an identical PTEN c.950_953delTACT mutation in either germline or somatic sources of DNA, respectively. Negative or moderate expression levels of PTEN were validated by immunohistochemistry in the corresponding patients' affected tissues. This study has revealed a novel pathogenicity locus to LDD/CS as a candidate for early molecular diagnosis. In addition, the differential PTEN mutation status with corresponding LDD phenotypes suggests a potential correlation between germline or somatic mutation and coexisting LDD/CS or isolated LDD, respectively. Furthermore, our data could lend some reference to the underlying molecular mechanism of LDD pathogenesis in the future.