|(1) Ichthyoses, also known as disorders of
keratinization, encompass a heterogeneous group of hereditary and
acquired skin diseases, characterized by the presence of visible
scales on the skin surface.
(2) The word
ichthyosis comes from the Greek word
ichthys, meaning fish, referring to the cutaneous scaling that
is characteristic of these disorders, which is said to resemble the
scales of a fish.
ichthyoses are primarily inherited disorders with onset at or
shortly after birth, rare acquired forms have been reported in the
setting of malignancy, nutritional deficiency, and autoimmune or
(4) Mutations in over
50 genes have been reported to cause ichthyoses.
vulgaris and X-linked recessive ichthyosis are classified as the
(6) It is the most
common form of nonsyndromic inherited ichthyosis, with an estimated
incidence of 1 in 250 births.
(7) Clinical findings
usually appear at around 2 months of age and include generalized
xerosis and fine white to gray scale that is most prominent on the
abdomen, chest, and extensor surfaces of the extremities.
(8) It is caused by
autosomal dominant mutations in the filaggrin gene (FLG),
which plays an essential role in epidermal differentiation and
formation of the skin barrier.
recessive ichthyosis is the second most common form of inherited
ichthyosis, with a prevalence of 1:2000 to 1:6000 in males.
recessive congenital ichthyosis is a genetically and phenotypically
heterogeneous group of disorders that includes harlequin ichthyosis,
lamellar ichthyosis and congenital ichthyosiform erythroderma.
It's incidence has been approximated at 1 in 200,000 births.
ichthyosis is caused by loss-of-function mutations in
ABCA12. Neonates present with
thick, armor-like scale with severe ectropion (eversion of the
eyelids), eclabium (eversion of the lips), and flattening of the
There is massive
hyperkeratosis in all biopsies.
Ichthyosis is characterized by large plate-like scales of ichthyosis.
It may present as "collodion baby". The palms and soles are often
involved. An increased incidence of skin cancer has been reported in
ichthyosis is a group of disorders caused by mutations in the
keratin family of genes. The major variant of keratinopathic
ichthyosis is epidermolytic ichthyosis.
ichthyosis is caused by autosomal dominant mutations in the keratin
1 ( KRT1) and keratin10 (KRT10)
genes, which play an essential role in maintaining structural
integrity in suprabasal keratinocytes.
(15) In addition to
cutaneous involvement, syndromic ichthyoses affect at least one
other organ or system. Many causative genes have been identified for
syndromic ichthyoses, including NSDHL
(CHILD syndrome), EBP (Conradi-Hunermann-Happle
syndrome, CHILD Syndrome) and ALDH3A2