Isolated hyperchlorhidrosis (HYCHL) is an autosomal recessive condition in which excessive salt wasting in sweat can result in severe infantile hyponatremic dehydration and hyperkalemia (summary by Muhammad et al., 2011).

Netherton syndrome (NETH) is a rare and severe autosomal recessive skin disorder characterized by congenital erythroderma, a specific hair-shaft abnormality, and atopic manifestations with high IgE levels. Generalized scaly erythroderma is apparent at or soon after birth and usually persists. Scalp hair is sparse and brittle with a characteristic 'bamboo' shape under light microscopic examination due to invagination of the distal part of the hair shaft to its proximal part. Atopic manifestations include eczema-like rashes, atopic dermatitis, pruritus, hay fever, angioedema, urticaria, high levels of IgE in the serum, and hypereosinophilia. Life-threatening complications are frequent during the neonatal period, including hypernatremic dehydration, hypothermia, extreme weight loss, bronchopneumonia, and sepsis. During childhood, failure to thrive is common as a result of malnutrition, metabolic disorders, chronic erythroderma, persistent cutaneous infections, or enteropathy (summary by Bitoun et al., 2002).

Autosomal recessive epidermolytic hyperkeratosis-2B (EHK2B) is a rare and clinically variable defect of cornification characterized by generalized erythema, erosions, scaling, and easily breaking blisters that become less frequent later in life, while hyperkeratosis increases (summary by Terheyden et al., 2009). For a discussion of genetic heterogeneity of epidermolytic hyperkeratosis, see EHK1 (113800).