AUTOSOMAL
RECESSIVE
CONGENITAL
ICHTHYOSIS
The term autosomal recessive congenital ichthyosis is useful to describe a heterogeneous group of disorders that present at birth with generalized involvement of the skin. ARCI can be syndromic, when accompanied by manifestations in other organ systems, or nonsyndromic. Autosomal recessive ichthyosis is rare and has been estimated to occur in about 1 in 300,000 persons.
In older literature, non-bullous congenital ichthyosiform erythroderma (NCIE, lamellar ichthyosis, with autosomal recessive inheritance) was distinguished from bullous congenital ichthyosiform erythroderma (epidermolytic hyperkeratosis, with autosomal dominant inheritance) based on clinical appearance (bullae) and pattern of inheritance. That the term lamellar ichthyosis was used interchangeably with NCIE and included a spectrum of phenotypes has led to some confusion. Williams and Elias distinguished lamellar ichthyosis from NCIE [usually called congenital ichthyosiform erythroderma (CIE)], a milder erythrodermic form. Some patients with lamellar ichthyosis can be clearly distinguished from those with CIE on the basis of clinical features. In lamellar ichthyosis, one sees large, dark, plate-like scale, and although infants may be red at birth, adults
have little to no erythroderma . In the more severe, classic presentation of lamellar ichthyosis, tautness of the facial skin leads to traction on the eyelids and lips, leading to ectropion and eclabium. Scarring alopecia, most prominent at the periphery of the scalp, may be partly due to traction at the hair line. In contrast, CIE has generalized redness and fine, white scale . Patients with classic CIE have little to no ectropion, eclabium, or alopecia. However, many patients do not fit neatly into these two clinical descriptions,47 in that they have features of both lamellar ichthyosis and CIE and a clinical phenotype intermediate between both disorders. Therefore, it can be useful to consider these two distinctive presentations as ends of a spectrum, between which lie a gradation of clinical phenotypes with variable degrees of erythema and coarseness of scale. Individual features, such as collodion membrane (discussed in Collodion Baby under Ichthyosis in the Newborn), ectropion, and alopecia, can occur across the spectrum. The collodion presentation may, over time, evolve into a disease that falls anywhere within the clinical spectrum of severity and can develop into lamellar ichthyosis, CIE, or have minimal involvement (self-healing collodion baby).48 Although attempts to refine the categorization of these disorders by using biochemical and ultrastructural observations have failed to yield a consistent and replicable classification scheme, identification of the spectrum of specific molecular defects underlying these conditions will undoubtedly help.
Most patients with lamellar ichthyosis or CIE inherit the disease in an autosomal recessive pattern. Rarely, families have been described with similar phenotypes, where the disease is inherited as an autosomal dominant trait.5 This is an important consideration for genetic counseling.