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Abnormal large granules in several cell types, including granulocytes, melanocytes, NK cells, and platelets, as well as decreased bactericidal activity of neutrophils are among hematologic findings of Chediak-Higashi syndrome (CHS) About 50–85% of patients with CHS eventually enter an accelerated phase, manifested by fever, lymphadenopathy, anemia, jaundice, neutropenia, thrombocytopenia, and widespread lymphohistiocytic organ infiltrates The Griscelli-syndrome type 2 should be considered as an alternative diagnosis in patients with mild skin hypopigmentation and silvery gray hair, but platelet function is normal in these patients The distinction between CHS and Hermansky-Pudlak syndrome type 2 depends on identifying giant intracellular granules within neutrophils of individuals with CHS

Albinism is a generic clinical term that describes conditions characterized by hypopigmentation of skin, hair, and eyes or eyes alone of affected individuals. It is caused by pathologic variants of genes that are associated with melanin synthesis, melanocyte differentiation/migration, or membrane trafficking. Although these are generally rare conditions, some types of albinism are seen more frequently in certain regions as a result of the founder effect (Ito et al., J Invest Dermatol 125(4):715–720, 2005; Okoro, Br J Dermatol 92(5):485–492, 1975).

Hair abnormalities can be of considerable psychosocial significance to both children and adults, and can serve as a marker for systemic disease, whether it be inherited or acquired. Similarly, nail changes, such as discoloration or thickening, can represent a local phenomenon (as seen in onychomycosis) or be a herald of general health.

Inherited platelet disorders are usually classified according to the defect in the platelets. These comprise defects of platelet receptors, signal transduction, cytoskeleton, and platelet granule secretion. Platelet α-granules, δ-granules, or both may be affected resulting in phenotypical changes. According to the disorder platelet size and morphology can also be altered.

Myosins are cytoskeletal motor proteins that use energy derived from ATP hydrolysis to generate force and movement along actin filaments. Humans express 38 myosin genes belonging to 12 classes that participate in a diverse range of crucial activities, including muscle contraction, intracellular trafficking, cell division, motility, actin cytoskeletal organisation and cell signalling. Myosin malfunction has been implicated a variety of disorders including deafness, hypertrophic cardiomyopathy, Usher syndrome, Griscelli syndrome and cancer. In this chapter, we will first discuss the key structural and kinetic features that are conserved across the myosin family. Thereafter, we summarise for each member in turn its unique functional and structural adaptations, cellular roles and associated pathologies. Finally, we address the broad therapeutic potential for pharmacological interventions that target myosin family members.