Griscelli syndrome without hemophagocytosis in an eleven-year-old girl: expanding the phenotypic spectrum of Rab27A mutations in humans

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.

Discerning clinicopathological features of congenital neutropenia syndromes: an approach to diagnostically challenging differential diagnoses

The congenital neutropenia syndromes are rare haematological conditions defined by impaired myeloid precursor differentiation or function. Patients are prone to severe infections with high mortality rates in early life. While some patients benefit from granulocyte colony-stimulating factor treatment, they may still face an increased risk of bone marrow failure, myelodysplastic syndrome and acute leukaemia. Accurate diagnosis is crucial for improved outcomes; however, diagnosis depends on familiarity with a heterogeneous group of rare disorders that remain incompletely characterised. The clinical and pathological overlap between reactive conditions, primary and congenital neutropenias, bone marrow failure, and myelodysplastic syndromes further clouds diagnostic clarity.We review the diagnostically useful clinicopathological and morphological features of reactive causes of neutropenia and the most common primary neutropenia disorders: constitutional/benign ethnic neutropenia, chronic idiopathic neutropenia, cyclic neutropenia, severe congenital neutropenia (due to mutations in ELANE, GFI1, HAX1, G6PC3, VPS45, JAGN1, CSF3R, SRP54, CLPB and WAS), GATA2 deficiency, Warts, hypogammaglobulinaemia, infections and myelokathexis syndrome, Shwachman-Diamond Syndrome, the lysosomal storage disorders with neutropenia: Chediak-Higashi, Hermansky-Pudlak, and Griscelli syndromes, Cohen, and Barth syndromes. We also detail characteristic cytogenetic and molecular factors at diagnosis and in progression to myelodysplastic syndrome/leukaemia.

The role of genetic selection and climatic factors in the dispersal of anatomically modern humans out of Africa

The evolutionarily recent dispersal of anatomically modern humans (AMH) out of Africa (OoA) and across Eurasia provides a unique opportunity to examine the impacts of genetic selection as humans adapted to multiple new environments. Analysis of ancient Eurasian genomic datasets (~1,000 to 45,000 y old) reveals signatures of strong selection, including at least 57 hard sweeps after the initial AMH movement OoA, which have been obscured in modern populations by extensive admixture during the Holocene. The spatiotemporal patterns of these hard sweeps provide a means to reconstruct early AMH population dispersals OoA. We identify a previously unsuspected extended period of genetic adaptation lasting ~30,000 y, potentially in the Arabian Peninsula area, prior to a major Neandertal genetic introgression and subsequent rapid dispersal across Eurasia as far as Australia. Consistent functional targets of selection initiated during this period, which we term the Arabian Standstill, include loci involved in the regulation of fat storage, neural development, skin physiology, and cilia function. Similar adaptive signatures are also evident in introgressed archaic hominin loci and modern Arctic human groups, and we suggest that this signal represents selection for cold adaptation. Surprisingly, many of the candidate selected loci across these groups appear to directly interact and coordinately regulate biological processes, with a number associated with major modern diseases including the ciliopathies, metabolic syndrome, and neurodegenerative disorders. This expands the potential for ancestral human adaptation to directly impact modern diseases, providing a platform for evolutionary medicine.

Hemiparesis Revealing a Unique Neurological Hemophagocytic Lymphohistiocytosis in a Patient With Griscelli Syndrome Type 2

Griscelli syndrome (GS) is a rare genetic disorder that encompasses three different subtypes (GS type 1 (GS1), GS type 2 (GS2), and GS type 3 (GS3)), in which isolated neurological manifestations without immune system implications are typically seen in GS1, while neurological involvements in GS2 should be attributed to the macrophage and lymphocyte invasion of the central nervous system (CNS), under associated hemophagocytic lymphohistiocytosis (HLH). The presence of the clinical, biological, and hematologic features of HLH help explain the neurological defects that GS2 patients unusually present. In our case report, however, we attempt to highlight an uncommon presentation of GS2 involving a hemiparesis, along which we did not have any clinical or biological features of HLH. We also collect and evaluate similar published cases that feature this problem of explaining the neurological manifestations among GS2 patients.

A founder RAB27A variant causes Griscelli syndrome type 2 with phenotypic heterogeneity in Qatari families

Griscelli syndrome type 2 (GS2) is a rare autosomal recessive disorder caused by pathogenic variants in the RAB27A gene and characterized by partial albinism, immunodeficiency, and occasional hematological and neurological involvement. We reviewed and analyzed the medical records of 12 individuals with GS2 from six families belonging to a highly consanguineous Qatari tribe and with a recurrent pathogenic variant in the RAB27A gene (NM_004580.4: c.244C > T, p.Arg82Cys). Detailed demographic, clinical, and molecular data were collected. Cutaneous manifestations were the most common presentation (42%), followed by neurological abnormalities (33%) and immunodeficiency (25%). The most severe manifestation was HLH (33%). Among the 12 patients, three patients (25%) underwent HSCT, and four (33%) died. The cause of death in all four patients was deemed HLH, providing evidence for this complication's fatal nature. Interestingly, two affected patients (16%) were asymptomatic. This report highlights the broad spectrum of clinical presentations of GS2 associated with a founder variant in the RAB27A gene (c.244C > T, p.Arg82Cys). Early suspicion of GS2 among Qatari patients with cutaneous manifestations, neurological findings, immunodeficiency, and HLH would shorten the diagnostic odyssey, guide early and appropriate treatment, and prevent fatal outcomes.

TREC and KREC profiling as a representative of thymus and bone marrow output in patients with various inborn errors of immunity

Primary immune deficiency (PID) disorders are clinically and molecularly heterogeneous diseases. T cell receptor excision circles (TRECs) and κ (kappa)-deleting excision circles (KRECs) are markers of T and B cell development, respectively. They are useful tools to assess T and B cell function and immune reconstitution and have been used for newborn screening for severe combined immunodeficiency disease (SCID) and agammaglobulinemia, respectively. Their profiles in several genetically confirmed PIDs are still lacking. The objective of this study was to determine TREC and KREC genomic profiling among various molecularly confirmed PIDs. We used real-time-quantitative polymerase chain reaction (RT-qPCR)-based triplex analysis of TRECs, KRECs and β-actin (ACTB) in whole blood genomic DNA isolated from 108 patients with molecularly confirmed PIDs. All agammaglobulinemia patients had low KREC counts. All SCIDs and Omenn syndrome patients secondary to mutations in RAG1, RAG2, DCLRE1C and NHEJ1 had low TREC and KREC counts. JAK3-deficient patients had normal KREC and the TREC count was influenced by the type of mutation. Early-onset ADA patients had low TREC and KREC counts. Four patients with zeta-chain-associated protein kinase 70 (ZAP70) had low TREC. All purine nucleoside phosphorylase (PNP) patients had low TREC. Combined immunodeficiency (CID) patients secondary to AK2, PTPRC, CD247, DCLREC1 and STAT1 had normal TREC and KREC counts. Most patients with ataxia-telangiectasia (AT) patients had low TREC and KREC, while most DOCK8-deficient patients had low TRECs only. Two of five patients with Wiskott-Aldrich syndrome (WAS) had low TREC counts as well as one patient each with bare lymphocyte syndrome (BLS) and chronic granulomatous disease. All patients with Griscelli disease, Chediak-Higashi syndrome, hyper-immunoglobulin (Ig)M syndrome and IFNGR2 had normal TREC and KREC counts. These data suggest that, in addition to classical SCID and agammaglobulinemia, TREC/KREC assay may identify ZAP70 patients and secondary target PIDs, including dedicator of cytokinesis 8 (DOCK8) deficiency, AT and some individuals with WAS and BLS.

Seizure as the presenting manifestation in Griscelli syndrome type 2

BACKGROUND

Griscelli syndrome is an autosomal recessive disease that is characterized by hypopigmentation of the skin and hair, presence of large clumps of pigment in hair shafts, and accumulation of melanosomes in melanocytes; it resembles Chediak-Higashi syndrome. Griscelli syndrome type 2 is caused by mutations in the RAB27A gene and has predominant immunologic abnormalities.

METHOD

A retrospective case analysis highlighting neurological complications in an individual with Griscelli syndrome type 2.

RESULTS

We present a 1-year-old girl with Griscelli syndrome type 2 in an Asian Indian family, confirmed by mutation analysis of the RAB27A gene. She presented with seizures and regression of developmental milestones following a brief febrile illness. Progressive neurological deterioration was associated with refractory status epilepticus. Neurological worsening may have resulted from the accelerated phase of the disease.

CONCLUSION

Griscelli syndrome type 2 is a rare primary immunodeficiency state with characteristic silvery hair, partial albinism, and immunological abnormalities. Predominant neurological presentation is rare, but it represents isolated central nervous system hemophagocytosis.

Griscelli syndrome type 2: a novel mutation in RAB27A gene with different clinical features in 2 siblings: a diagnostic conundrum

Griscelli syndrome type 2 (GS2) is a rare autosomal recessive disease caused by mutations in the RAB27A gene. It is characterized by cutaneous hypopigmentation, immunodeficiency, and hemophagocytic lymphohistiocytosis. We describe 2 brothers who had GS2 with clinically diverse manifestations. The elder brother presented with a purely neurological picture, whereas the younger one presented with fever, pancytopenia, hepatosplenomegaly, and erythema nodosum. Considering that cutaneous hypopigmentation was a common feature between the brothers, genetic analysis for Griscelli syndrome was performed. As the elder sibling had died, mutation analysis was only performed on the younger sibling, which revealed a novel homozygous mutation in the RAB27A gene on chromosome 15 showing a single-base substitution (c.136T>A p.F46I). Both parents were heterozygous for the same mutation. This confirmed the diagnosis of GS2 in the accelerated phase in both siblings. The atypical features of GS2 in these cases are a novel mutation, isolated neurological involvement in one sibling, association with erythema nodosum, and 2 distinct clinical presentations in siblings with the same genetic mutation.

Endocytosis and signaling: cell logistics shape the eukaryotic cell plan

Our understanding of endocytosis has evolved remarkably in little more than a decade. This is the result not only of advances in our knowledge of its molecular and biological workings, but also of a true paradigm shift in our understanding of what really constitutes endocytosis and of its role in homeostasis. Although endocytosis was initially discovered and studied as a relatively simple process to transport molecules across the plasma membrane, it was subsequently found to be inextricably linked with almost all aspects of cellular signaling. This led to the notion that endocytosis is actually the master organizer of cellular signaling, providing the cell with understandable messages that have been resolved in space and time. In essence, endocytosis provides the communications and supply routes (the logistics) of the cell. Although this may seem revolutionary, it is still likely to be only a small part of the entire story. A wealth of new evidence is uncovering the surprisingly pervasive nature of endocytosis in essentially all aspects of cellular regulation. In addition, many newly discovered functions of endocytic proteins are not immediately interpretable within the classical view of endocytosis. A possible framework, to rationalize all this new knowledge, requires us to "upgrade" our vision of endocytosis. By combining the analysis of biochemical, biological, and evolutionary evidence, we propose herein that endocytosis constitutes one of the major enabling conditions that in the history of life permitted the development of a higher level of organization, leading to the actuation of the eukaryotic cell plan.

Clinical presentation of Griscelli syndrome type 2 and spectrum of RAB27A mutations

BACKGROUND

Griscelli syndrome type 2 (GS2) is an autosomal-recessive immunodeficiency caused by mutations in RAB27A, clinically characterized by partial albinism and haemophagocytic lymphohistocytosis (HLH). We evaluated the frequency of RAB27A mutations in 21 unrelated patients with haemophagocytic syndromes without mutations in familial HLH (FHL) causing genes or an established diagnosis of GS2. In addition, we report three patients with known GS2. Moreover, neurological involvement and RAB27A mutations in previously published patients with genetically verified GS2 are reviewed.

PROCEDURE

Mutation analysis of RAB27A was performed by direct DNA sequencing. NK cell activity was evaluated and microscopy of the hair was performed to confirm the diagnosis.

RESULTS

RAB27A mutations were found in 1 of the 21 families. This Swedish family had three affected children with heterozygous compound mutations consisting of a novel splice error mutation, [c.239G>C], and a nonsense mutation, [c.550C>T], p.R184X. The three additional children all carried homozygous RAB27A mutations, one of which is a novel splice error mutation, [c.240-2A>C]. Of note, five of the six patients displayed neurological symptoms, while three out of six patients displayed NK cell activity within normal reference values, albeit low. A literature review revealed that 67% of GS2 patients have been reported with neurological manifestations.

CONCLUSIONS

Identification of RAB27A mutations can facilitate prompt diagnosis and treatment, and aid genetic counselling and prenatal diagnosis. Since five of six patients studied herein initially were diagnosed as having FHL, we conclude that the diagnosis of GS2 may be overlooked, particularly in fair-haired patients with haemophagocytic syndromes.

Griscelli syndrome-type 2 in twin siblings: case report and update on RAB27A human mutations and gene structure

Griscelli syndrome (GS) is a rare autosomal recessive disorder caused by mutation in the MYO5A (GS1, Elejalde), RAB27A (GS2) or MLPH (GS3) genes. Typical features of all three subtypes of this disease include pigmentary dilution of the hair and skin and silvery-gray hair. Whereas the GS3 phenotype is restricted to the pigmentation dysfunction, GS1 patients also show primary neurological impairment and GS2 patients have severe immunological deficiencies that lead to recurrent infections and hemophagocytic syndrome. We report here the diagnosis of GS2 in 3-year-old twin siblings, with silvery-gray hair, immunodeficiency, hepatosplenomegaly and secondary severe neurological symptoms that culminated in multiple organ failure and death. Light microscopy examination of the hair showed large, irregular clumps of pigments characteristic of GS. A homozygous nonsense mutation, C-T transition (c.550C>T), in the coding region of the RAB27A gene, which leads to a premature stop codon and prediction of a truncated protein (R184X), was found. In patient mononuclear cells, RAB27A mRNA levels were the same as in cells from the parents, but no protein was detected. In addition to the case report, we also present an updated summary on the exon/intron organization of the human RAB27A gene, a literature review of GS2 cases, and a complete list of the human mutations currently reported in this gene. Finally, we propose a flow chart to guide the early diagnosis of the GS subtypes and Chédiak-Higashi syndrome.

Griscelli syndrome type 2: a rare and lethal disorder

Griscelli syndrome is a rare autosomal recessive disorder. It is characterized by pigment dilution and variable immune deficiency leading to increased susceptibility to certain infections and a tendency to develop a life-threatening hemophagocytic syndrome known as the accelerated phase. Griscelli syndrome is now classified into 3 types based on the genetic and molecular features. Primary neurological presentation without the accelerated phase is rare in type 2. In this article, the authors report a boy who was presented with seizures and diffuse white matter involvement unaccompanied by the other features of the accelerated phase. Mutation analysis in family members revealed the presence of a missense mutation in Rab27a gene. In addition to the rare presentation, this is the first case of Griscelli syndrome to be reported from Jordan.

A novel missense mutation (G43S) in the switch I region of Rab27A causing Griscelli syndrome

The autosomal recessive Griscelli syndrome type II (GSII) is caused by mutations in the RAB27A gene. Typical clinical features include immunological impairment, silver-gray scalp hair, eyelashes and eyebrows and hypomelanosis of the skin. Rabs help determine the specificity of membrane trafficking steps within cells. In melanocytes, the GTP-bound form of Rab27A associates with the membranes of mature fully-pigmented melanosomes through its geranylgeranyl group. Once attached, Rab27A recruits the downstream effector Melanophilin (Mlph) and the actin-dependent motor protein Myosin Va (MyoVa). The molecular Rab27A/Mlph/MyoVA tripartite complex, which links melanosomes to the peripheral actin network, is required to achieve melanosome transfer to surrounding keratinocytes in the epidermis. Here we report a novel homozygous missense mutation c.127G>A, p.G43S in exon 2 of the RAB27A gene of an Afghani GSII patient. Laser scanning confocal microscopy showed that the G43S mutation, which is located in the highly conserved switch I region of Rab27A, induces perinuclear localization of melanosomes in normal melanocytes, and fails to restore melanosomes to the actin-rich periphery in GSII melanocytes. Co-immunoprecipitation studies showed that Rab27A(G43S) fails to interact with its effector Melanophilin, indicating that the switch I region functions in the recruitment of Rab effector proteins.

Analysis of RAB27A gene in griscelli syndrome type 2: novel mutations including a deletion hotspot

INTRODUCTION

Griscelli syndrome type 2 is an autosomal recessive disorder characterized by pigmentary dilution and occurrence of acute phases of hemophagocytosis. The disease is caused by mutations in RAB27A gene, coding a small GTPase involved in terminal phases of cytotoxic granule/melanosome exocytosis.

MATERIALS AND METHODS

We describe the result of mutation analysis among nine patients from seven non-related Persian families. We present four novel mutations including a deletion hot spot (514del 5).

CONCLUSION

This hot spot is flanked by "direct repeats" of nucleotides, which are previously shown to be associated with areas of recurrent small deletions.

Griscelli syndrome: a case report

A 10-year-old boy presented with partial albinism and typical clinical features of a macrophage activation syndrome (hepatosplenomegaly, fever, and pancytopenia), suggesting the diagnosis of Griscelli syndrome. The diagnosis was confirmed by light microscopic evaluation of hair that showed characteristic large aggregates of pigment granules irregularly distributed along the hair shaft. Immunosuppressive therapy controlled his macrophage activation syndrome successfully. Since early diagnosis is life saving and simple methods confirm the diagnosis, finding of partial albinism in children should alert clinicians to consider Griscelli syndrome.

Neurological presentation of Griscelli syndrome: obstructive hydrocephalus without haematological abnormalities or organomegaly

Griscelli syndrome is a rare autosomal-recessive disorder characterised by partial albinism, immunodeficiency, organomegaly and accelerated phases. During accelerated phases, pancytopenia, haemophagocytosis, hypoproteinemeia occur which may be accompanied by neurological deterioration. Primary neurological presentation is rare and we report a case that presented with obstructive hydrocephalus and infiltrative lesions in the brain unaccompanied by other features of accelerated phase. Biopsy of these lesions demonstrated sinus histiocytosis. Electron microscopy of hair shaft and genetic studies established the diagnosis of Griscelli disease with RAB 27A mutation.

Griscelli syndrome: description of a case with Rab27A mutation

A 7-month-old Turkish boy presented with partial albinism and typical clinical features of an accelerated phase, suggesting the diagnosis of Griscelli syndrome. The diagnosis was confirmed by light microscopic evaluation of hair and a peripheral blood smear. Genetic analysis identified a mutation in the Rab27A gene. He was initiated immunosuppressive treatment but accelerated phase could not be ameliorated. He unfortunately died from multiorgan failure. The finding of partial albinism in children should alert clinicians to consider Griscelli syndrome since simple methods can confirm the diagnosis and early diagnosis is life-saving.

Common variable immunodeficiency: test indications and interpretations

Common variable immunodeficiency (CVID) is a primary immunodeficiency disorder that can present with multiple phenotypes, all of which are characterized by hypogammaglobulinemia, in a person at any age. A specific genetic defect that accounts for all CVID phenotypes has not been identified, and it is likely that several distinct genetic disorders with similar clinical presentations are responsible for the observed variation. In this review, we summarize the known genetic mutations that give rise to hypogammaglobulinemia and how these gene products affect normal or abnormal B-cell development and function, with particular emphasis on CVID. Additionally, we describe specific phenotypic and genetic laboratory tests that can be used to diagnose CVID and provide guidelines for test interpretation and subsequent therapeutic intervention.