Neuroectodermal Melanolysosomal Disease

Elejalde syndrome (ES) is characterized by silvery to leaden hair, bronze skin colour in sun-exposed areas and severe neurological impairment.

Epidemiology

The syndrome was first described in 1979 in three consanguineous families. To date, about 20 patients have been reported in the literature.

Clinical description

It is either congenital or develops during childhood (seizures, severe hypotonia and intellectual deficit). There is no impairment of the immune system and a wide spectrum of ophthalmologic abnormalities has been described. ES hair samples show irregular clumps of melanin under the microscope and skin melanocytes contain many irregularly shaped melanosomes with an incomplete transfer-block towards surrounding keratinocytes. Ultrastructurally, abnormal inclusion bodies are observed in fibroblasts, bone marrow histiocytes and lymphocytes.

Etiology

The etiology of ES is still unknown, but recent molecular data have shed light on the complex relationship that exists between ES and the Griscelli syndrome (see this term). Mutations in the myosin Va gene (MYOVA) result in the so-called Griscelli syndrome type 1, characterized by cutaneous and neurologic manifestations. MYOVA encodes myosin Va, an actin-based motor protein important for the intracellular transport of organelles in melanocyte and neuronal cells. It is very likely that Griscelli syndrome type 1 corresponds to ES.

Differential diagnosis

The main differential diagnoses are Griscelli syndrome type 2 (caused by mutations in RAB27A), which is characterized by cutaneous and immunological manifestations, without primary neurological signs; Griscelli syndrome type 3, which has only cutaneous hypopigmentation as a feature and is caused by mutations in MLPH; and Chediak-Higashi syndrome (see this term), also characterized by silvery hair, and by oculocutaneous hypopigmentation. It can lead to death by infection and/or lymphoma-like organ infiltration (so-called accelerated phases), and is caused by mutations in the LYST gene.

Management and treatment

Treatment for ES remains limited: corticosteroids, anticonvulsants and antipyretics fail to prevent early death from severe neurologic dysfunction.