Prenatal diagnosis of Chediak-Higashi syndrome

Accelerated Phase of Chediak-Higashi Syndrome at Initial Presentation: A Case Report of an Uncommon Occurrence in a Rare Disorder

Chediak-Higashi syndrome (CHS) is an uncommon and fatal congenital disorder. The characteristic features of CHS are partial oculocutaneous albinism, increased vulnerability to infections, presence of abnormal large granules in leukocytes and an accelerated lymphohistiocytic phase. Accelerated phase at initial presentation is rarely seen as it is usually preceded by repeated episodes of infections. Hence this interesting case of a four-month-old Indian child born to consanguineous parents in accelerated phase at initial presentation is described. The boy presented with fever, hepatosplenomegaly, and cleft lip. Clinical diagnosis was leukemia or a lysosomal storage disorder. Cytopaenias, lymphohistiocytic infiltration in bone marrow, and the characteristic large granules in leucocytes helped in the diagnosis, emphasizing the importance of bone marrow in diagnosis of unusual presentation of this rare disorder.

Congenital Platelet Disorders

Congenital platelet disorders represent a rare group of diseases classified by either a qualitative or quantitative platelet defect. This article outlines the historical, clinical, laboratory, and genetic features of various inherited platelet disorders with attention given to updated information on disease classification, diagnosis, and genotypes. A separate discussion regarding management addresses the difficulty in treatment strategies, particularly in patients who develop alloimmunization to platelets.

Diagnóstico pré-natal das genodermatoses

O diagnóstico pré-natal está indicado para algumas genodermatoses graves, como a epidermólise bolhosa distrófica recessiva e a epidermólise bolhosa juncional. A biópsia de pele fetal foi introduzida em 1980, mas não pode ser realizada antes da 15a semana de gestação. A análise do DNA fetal é método preciso e pode ser realizado mais precocemente na gestação. No entanto, deve-se conhecer a base molecular da genodermatose, e é essencial determinar a mutação e/ou marcadores informativos nas famílias com criança previamente afetada. O DNA fetal pode ser obtido pela biópsia da vilosidade coriônica ou amniocentese. O diagnóstico genético pré-implantação tem surgido como alternativa que dispensa a interrupção da gestação. Essa técnica, que envolve fertilização in vitro e teste genético do embrião. vem sendo realizada para genodermatoses em poucos centros de referência. A ultra-sonografia é exame não invasivo, mas tem uso limitado no diagnóstico pré-natal de genodermatoses. A ultrasonografia tridimensional geralmente estabelece o diagnóstico tardiamente na gestação, e há apenas relatos anedóticos de diagnóstico pré-natal de genodermatoses usando esse método.

Clinical, molecular, and cell biological aspects of Chediak-Higashi syndrome

Chediak-Higashi syndrome (CHS) is a rare autosomal recessive disorder characterized by variable degrees of oculocutaneous albinism, easy bruisability, and bleeding as a result of deficient platelet dense bodies, and recurrent infections, with neutropenia, impaired chemotaxis and bactericidal activity, and abnormal NK cell function. Neurologic involvement is variable, but often includes peripheral neuropathy. Most patients also undergo an "accelerated phase," which is a nonmalignant lymphohistiocytic infiltration of multiple organs resembling lymphoma. Death often occurs in the first decade from infection, bleeding, or development of the accelerated phase. The hallmark of CHS is the presence of huge cytoplasmic granules in circulating granulocytes and many other cell types. These granules are peroxidase-positive and contain lysosomal enzymes, suggesting that they are giant lysosomes or, in the case of melanocytes, giant melanosomes. The underlying defect in CHS remains elusive, but the disorder can be considered a model for defects in vesicle formation, fusion, or trafficking. Because the beige mouse demonstrates many characteristics similar to those of human CHS patients, including dilution of coat color, recurrent infections, and the presence of giant granules, it is considered the animal homologue of CHS. The beige gene, Lyst, was mapped and sequenced in 1996, prompting identification of the human LYST gene on chromosome 1q42. Lyst and LYST show 86.5% sequence homology. LYST encodes a 429 kDa protein with a function that remains unknown, but the source of extensive speculation among students of cell biology.

Chédiak-Higashi syndrome: presentation of seven cases

CONTEXT

Chédiak-Higashi Syndrome (CHS) is a rare autosomal recessive disease characterized by recurrent infections, giant cytoplasmic granules, and oculocutaneous albinism.

OBJECTIVE

To describe clinical and laboratory findings from CHS patients.

DESIGN

Case report.

SETTING

The patients were admitted into the Allergy and Immunology Unit of the Instituto da Criança, a tertiary public care institution.

CASES REPORT

Seven patients had oculocutaneous albinism, recurrent infections and giant cytoplasmic granules in the leukocytes. One patient had low IgG levels and three showed impaired bactericidal activity of neutrophils. Six patients died of infectious complications during the accelerated phase. Therapy included ascorbic acid and antibiotics. Chemotherapy was used for the accelerated phase in two patients. Bone marrow transplantation (BMT) was proposed for one patient.

DISCUSSION

The authors emphasize the need for early diagnosis and therapy of CHS. BMT should be indicated before the accelerated phase of the disease has developed.

Genetic defects in Chediak-Higashi syndrome and the beige mouse

Chediak-Higashi syndrome (CHS) is a rare, autosomal recessive, multisystem disorder in which severe immune deficits are accompanied by abnormalities of pigmentation, blood clotting, and neurologic function. There is no specific treatment, and without bone marrow transplantation, most patients succumb to frequent bacterial infections or to a lymphoproliferative syndrome that appears to result principally from lack of natural killer cell function. Disorders similar to human CHS occur in many mammalian species, the most important being the beige mouse, long considered a likely homologue of human CHS. This supposition has recently been confirmed by the mapping, cloning, and mutation analysis of the homologous human CHS1 and mouse beige genes. Identification of the human CHS1 gene, and the availability of a ready mouse model for human CHS, will likely facilitate investigation of the disease pathophysiology and the development of novel and specific treatments for the disorder.

Partial albinism with immunodeficiency: Griscelli syndrome: report of a case and review of the literature

Partial albinism with immunodeficiency (Griscelli syndrome) is an uncommon disorder characterized by pigmentary dilution and variable immunodeficiency. Features include a silvery-gray sheen to the hair, large clumped melanosomes in hair shafts, and prominent mature melanosomes in cutaneous melanocytes with sparse pigmentation of adjacent keratinocytes. Immunologic abnormalities most often include impaired natural killer cell activity, absent delayed-type hypersensitivity, and impaired responses to mitogens. Impaired helper T cell function and hypogammaglobulinemia have also been described. The syndrome can be differentiated from Chediak-Higashi syndrome by pathognomonic light and electron microscopic features in skin and hair, and absence of consistent granulocyte abnormalities, but similarly carries a poor prognosis without bone marrow transplantation. We describe a patient with Griscelli syndrome who presented with hepatosplenomegaly, hepatitis, pancytopenia, and silvery hair in the newborn period.