Genetic analysis in three Egyptian patients with Griscelli syndrome Type 1 reveals new nonsense mutations in MYO5A

Role of the RAB27/SYTL Axis in Tumor Microenvironment Construction

Crosstalk between cancer cells and the tumor microenvironment (TME) is a key event in malignant progression and metastasis. The secretion of bioactive substances by cancer cells remodels the TME, affecting the activities of its components, including blood vessels, mesenchymal cells, and immune cells. These substances are effectively delivered through intracellular trafficking and exocytosis of cytoplasmic vesicles. The small guanosine triphosphatase (GTPase) RAB27 and its effectors, synaptotagmin-like (SYTL) family proteins, play essential roles in vesicle trafficking. Our recent research demonstrates the upregulation of RAB27A/B and SYTL1/2 in alveolar soft part sarcoma and acute myeloid leukemia. This enhanced trafficking promotes angiogenesis and the occupation of leukemia cells in the bone marrow niche. This review focuses on the role of the RAB27/SYTL axis in various cancer types associated with TME modifications, with a discussion on its importance as a therapeutic target.

Griscelli syndrome: a diagnostic challenge of a rare disease: a case report

Introduction

Griscelli syndrome (GS) is a rare autosomal recessive genetic disorder that primarily manifests as hair and skin hypopigmentation, with three types differentiated by their specific genetic defects as well as by their clinical features. Clinically, GS type 1 is characterized by early neurological alterations, while GS type 2 is characterized by immunodeficiency and could present with neurological symptoms, and type 3 is characterized by a chromosomal anomaly without a specific clinical profile besides hypopigmentation. This article details the challenges faced in the diagnosis of a patient with GS who presents with neurological symptoms followed by immunological deficits.

Case presentation

A 7-month-old female presented with complaints of developmental delay following an otitis media infection. Upon examination, she exhibited signs of psychomotor developmental regression and had pale bronze skin and silvery-gray hair, as well as hepatosplenomegaly. The examination of her hair shaft revealed a pattern consistent with GS. During her hospitalization, the patient developed an intermittent fever and signs of hemophagocytic lymphohistiocytosis (HLH). She subsequently developed recurrent seizures treated with phenytoin and Aciclovir. Shortly she succumbed to respiratory distress syndrome and multisystem failure.

Discussion

The presence of HLH confirms the type of GS. However, in some cases, the HLH criteria could not be fulfilled, presenting a diagnostic challenge.

Conclusion

The genetic examination is the only way to differentiate GS type 1 from type 2. However, when it is not available, the presence of specific symptoms and features may assist in the classification. Furthermore, treatments should be administered when GS type 2 is suspected since they have the potential to improve life quality through treating HLH, delaying and altering the neurological symptoms.

Griscelli syndrome type 1: a novel pathogenic variant, and review of literature

Griscelli syndrome type 1 (GS1) is a rare inherited autosomal recessive disease caused by a deleterious variant in the MYO5A gene and characterized by general hypopigmentation, neurological symptoms, motor disability, hypotonia, and vision abnormality. Only nine pathogenic variants in the MYO5A gene have been confirmed in association with the GS1. All of the reported pathogenic variants are truncating. Herein, two siblings from a consanguineous Iranian family with abnormal pigmentation and neurological symptoms were referred for genetic counseling. Whole-exome sequencing (WES) revealed a novel homozygous truncating variant c.1633_1634delAA (p.Asn545Glnfs*10) in the MYO5A gene, which was completely co-segregated with the phenotype in all affected and unaffected family members. Computational analysis and protein modeling demonstrated the deleterious effects of this variant on the structure and function of the protein. The variant, according to ACMG guidelines, was classified as pathogenic. Besides the novelty of the identified variant, our patients manifested more severe clinical symptoms and presented distal hyperlaxity in all four limbs, which was a new finding. In conclusion, we expanded the mutational and phenotypic spectrum of the GS1. Moreover, by studying clinical manifestations in all molecularly confirmed reported cases, provided a comprehensive overview of clinical presentation, and attempted to find a genotype-phenotype correlation.

Hair microscopy: an easy adjunct to diagnosis of systemic diseases in children

Hair, having distinct stages of growth, is a dynamic component of the integumentary system. Nonetheless, derangement in its structure and growth pattern often provides vital clues for the diagnosis of systemic diseases. Assessment of the hair structure by various microscopy techniques is, hence, a valuable tool for the diagnosis of several systemic and cutaneous disorders. Systemic illnesses like Comel-Netherton syndrome, Griscelli syndrome, Chediak Higashi syndrome, and Menkes disease display pathognomonic findings on hair microscopy which, consequently, provide crucial evidence for disease diagnosis. With minimal training, light microscopy of the hair can easily be performed even by clinicians and other health care providers which can, thus, serve as a useful tool for disease diagnosis at the patient's bedside. This is especially true for resource-constrained settings where access and availability of advanced investigations (like molecular diagnostics) is a major constraint. Despite its immense clinical utility and non-invasive nature, hair microscopy seems to be an underutilized diagnostic modality. Lack of awareness regarding the important findings on hair microscopy may be one of the crucial reasons for its underutilization. Herein, we, therefore, present a comprehensive overview of the available methods for hair microscopy and the pertinent findings that can be observed in various diseases.

Refractory Seizure in a Patient With Griscelli Syndrome: A Unique Case With One Mutation and a Novel Deletion

Griscelli syndrome (GS) is a rare syndrome characterized by hypopigmentation, immunodeficiency, and neurological features. The genes Ras-related protein (RAB27A) and Myosin-Va (MYO5A) are involved in this condition's pathogenesis. We present a GS type 1 (GS1) case with developmental delay, hypotonia, and refractory seizures despite multiple medications, which included clobazam, cannabinol, zonisamide, and a ketogenic diet. Lacosamide and levetiracetam were added to the treatment regimen, which decreased the seizures' frequency from 10 per day to five per day. The patient had an MYO5A mutation and, remarkably, a deletion on 18p11.32p11.31. The deletion was previously reported in a patient with refractory seizures and developmental delay. We reviewed all cases of GS that presented with seizures. We reviewed other cases of GS and seizures described in the literature and explored possible seizure mechanisms in GS. Seizure in GS1 seems to be related directly to the MYO5A mutation. The neurological manifestations in GS2 seem to be caused indirectly by the accelerated phase of Hemophagocytic syndrome (HPS), which is characteristic of GS2. By having the MYO5A gene mutation combined with the 18p11.32p11.31 deletion, the prognosis and severity of the patient's condition are poor. This is the first report of GS1 with a deletion in 18p11.32p11.31.

Diagnostic and therapeutic caveats in Griscelli syndrome

Griscelli syndrome (GS) is a rare autosomal recessive disease with characteristic pigment distribution, and there are currently 3 types according to the underlying genetic defect and clinical features. We present the case of a girl born from consanguineous parents who presented with predominant neurologic symptoms, silvery hair and granulomatous skin lesions. Cerebral magnetic resonance revealed diffuse white matter lesions, and central nervous system (CNS) lymphocytic infiltration was suspected. The patient underwent haematopoietic stem cell transplantation with graft failure and autologous reconstitution. She developed elevated liver enzyme with a cholestatic pattern. Multiple liver biopsies revealed centrilobular cholestasis and unspecific portal inflammation that improved with immunomodulatory treatment. She was revealed to have an impaired cytotoxicity in NK cells and a decreased expression of RAB27A. However, no variants were found in the gene. All types of GS present with pigment dilution and irregular pigment clumps that can be seen through light microscopy in hair and skin biopsy. Dermic granulomas and immunodeficiency with infectious and HLH predisposition have been described in GS type 2 (GS2). Neurologic alterations might be seen in GS type 1 (GS1) and GS type 2 (GS2), due to different mechanisms. GS1 presents with neurologic impairment secondary to myosin Va role in neuronal development and synapsis. Meanwhile, GS2 can present with neurologic impairment secondary to SNC HLH. Clinical features and cytotoxicity might aid in differentiating GS1 and GS2, especially since treatment differs.

Hair Shaft Examination: A Practical Tool to Diagnose Griscelli Syndrome

Griscelli syndrome (GS) is a rare disease that is characterized by silvery hair and fair skin. It is included in congenital grey hair syndromes, a rare group of autosomal recessive disorders characterized by silvery grey hair and severe multisystem disorders, such as immune system impairment, defects in immunological function, ocular and skeletal alterations, and nervous system defects. Herein, we report a rare case of GS type 1 and highlight the importance of a dermatological and hair examination to make an early diagnosis of these life-threatening diseases.

Vici syndrome in an Egyptian infant: case report and differential diagnosis of inherited hypopigmented disorders

Background

Vici syndrome is a severe inherited multisystem disease caused by mutations in the EPG5 gene. The diagnosis depends on the constellation of cardinal features of agenesis of the corpus callosum, cataracts, oculocutaneous hypopigmentation, cardiomyopathy, and a combined immunodeficiency followed by confirmation by genetic testing. We report an Egyptian infant with Vici syndrome carrying a homozygous splice site variant (c.1252+1G>T; NM_020964.2) in the EPG5 gene, detailed clinical description, outcome, and differential diagnosis of inherited hypopigmentation disorders associated with neurological manifestations.

Case presentation

The infant initially presented with oculocutaneous hypopigmentation, agenesis of the corpus callosum, and immunodeficiency. A few months later, a diagnosis of dilated cardiomyopathy was made. Family history revealed 2 deceased siblings phenotypically matching our index infant. He died at the age of 15 months with acute respiratory failure.

Conclusion

The accurate diagnosis of such rare diseases with genetic confirmation is vital for proper clinical decision-making, genetic counseling of the affected families, and future genotype-phenotype correlation studies.