Congenital ichthyosis constitutes a group of genetic conditions that are not part of a certain syndrome and generally manifests with excessive keratinization of the skin. To this day, five types of congenital, inherited ichthyosis have been described, including X-linked ichthyosis, epidermolytic hyperkeratosis, ichthyosis vulgaris, congenital ichthyosiform erythroderma, and lamellar ichthyosis.
The common characteristic among all congenital ichthyosis types is the abnormal cornification and keratinization of the skin, resulting in dry scales that cover various body parts. Skin inflammation and systemic symptoms can accompany the dermatologic alterations, as can pruritus, anhidrosis, ectropion, and an irregularly dense stratum corneum . Frequently, manifestations are clearly noted at birth. More specifically:
- Lamellar ichthyosis: It results in the clinical picture of a "collodion baby". The collodion is a translucent membrane that is firmly attached to the newborn skin and falls of after approximately 2 weeks. Underneath the collodion membrane, scales that could attribute to a fish-like, disfiguring image are revealed . Large scales are more commonly observed in the legs and feet, and superficial fissures can be found in-between. Palms and soles can be severely affected, with hyperkeratotic plaques covering the entire area; scales may also appear on the scalp, leading sometimes to scarring alopecia . Ectropion is frequently diagnosed, and seizures caused by thermoregulatory problems may further complicate the clinical picture .
- X-linked ichthyosis: Scales are usually found on the torso and lower and upper extremities; as the patient ages, they may assume a darker color. The palms, mid-face, antecubital and popliteal fossae are primarily scale-free. Female patients bearing the gene do not usually exhibit symptomatology, whereas male newborns develop the first symptoms either at birth or immediately after: some may be collodion babies, while others may only display peeling and shedding, with no scales on the soles and palms  .
- Congenital ichthyosiform erythroderma: Another rare occurrence of congenital ichthyosis which is inherited as an autosomal recessive disease. The disorder is characterized by fine white scales and widespread erythroderma. Ectropion, alopecia affecting the scalp, anhidrosis, deformed nails, and eclabium are also characteristic manifestations of this congenital ichthyosis type .
- Ichthyosis vulgaris: Scales are primarily located on the elbows and calves; they are colored darker if the skin pigmentation is darker. Cracks may appear on the skin. An aggravation of the symptomatology is observed in the dry or cold environment.
- Epidermolytic hyperkeratosis: The condition is diagnosed at birth, with blistering areas covering the skin. Hyperkeratotic lesions start to develop a few months following birth; with time, blisters start to appear less often. Other coexisting disorders, not related to skin peeling and hyperkeratosis, such as hypocalcemic rickets and platelike osteoma cutis have also been rarely reported  .
Entire Body System
Identification of two novel PNPLA1 mutations in Turkish families with autosomal recessive congenital ichthyosis. Turk J Pediatr 2017; 59: 475-482. [ncbi.nlm.nih.gov]
Ichthyosis. ( 28815772 ) Hanson B....Maguiness S. 2017 34 A case of lamellar ichthyosis due to a novel TGM1 mutation associated with Parkinson's disease. ( 28747283 ) Morita-Adachi R....Akiyama M. 2017 35 Identification of two novel PNPLA1 mutations in Turkish [malacards.org]
For example, only two reports on mutations in CERS3 have been published on consanguineous Turkish and Tunisian families. 3, 4 Here we ascertained a large cohort of 140 distinct Iranian families affected by non-syndromic and syndromic forms of ichthyosis [nature.com]
- Increased Susceptibility to Infections
susceptibility to infections of the skin; heat intolerance is common Diagnostic tests: genetic testing of the blood Abnormal gene(s): mutations have been identified in a variety of genes including transglutaminase 1 (TGM1), 12R-lipoxygenase (ALOX12B) [firstskinfoundation.org]
Other signs and symptoms include skin inflammation and fragility, pruritus, erythema, fissuring and cracking of the skin, ectropion, anhidrosis (resulting in an increased susceptibility to overheating), and increased susceptibility to infection. [checkorphan.org]
- Disturbance of Growth
We delineate the criteria for distinguishing this gene defect from other types of congenital ichthyosis associated with disturbed hair growth, as well as from other types of trichothiodystrophy which are not associated with ichthyosis. [ncbi.nlm.nih.gov]
The hair loss is obviously a consequence of the ichthyosiform erythroderma, and therefore we propose for this type of pseudopelade the term alopecia ichthyotica. [ncbi.nlm.nih.gov]
In contrast, alopecia ichthyotica is a much neglected sign , though it may be of similar diagnostic value. [link.springer.com]
Both patients had severe developmental retardation, microcephalus, spastic quadriplegia, myoclonus, and hearing impairment. Cranial computed tomography and magnetic resonance imaging revealed diffuse cortical atrophy. [ncbi.nlm.nih.gov]
- Spastic Paraplegia
This family includes NIPA1, in which a mutation was recently described in a dominant form of spastic paraplegia (SPG6). We propose that ichthyin and NIPA1 are membrane receptors for ligands (trioxilins A3 and B3) from the hepoxilin pathway. [ncbi.nlm.nih.gov]
The various types of congenital ichthyosis are usually diagnosed at birth, based on the characteristic appearance of the newborn. In dubious cases, skin biopsy and histological analysis should be employed to ascertain a diagnosis. Steroid sulfatase activity (STS activity), cholesterol sulfate concentration, and genetic testing may be required to diagnose X-linked ichthyosis; lamellar ichthyosis can also be diagnosed via genetic testing. Single-gene testing may be chosen on some occasions .
The differential diagnosis should comprise Refsum disease, neutral lipid storage disease, Sjögren-Larsson syndrome, and Netherton syndrome. A complete workup also requires blood laboratory studies such as serum angiotensin-converting enzyme, lysozyme, complete blood count (CBC), thyroid-stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), as well as a chest radiography. Sometimes, congenital ichthyosis can also be detected prenatally via ultrasonography: a persistently open mouth, thick amniotic fluid, and persistently flexed extremities do suggest the possibility of ichthyosis. Diminished serum unconjugated estriol detected in the mother's blood during the period of pregnancy raises suspicion for X-linked ichthyosis.
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- Choudhary R, Satish V. Dental Treatment of a Child Suffering from Non-bullous Congenital Ichthyosiform Erythroderma under General Anesthesia. Int J Clin Pediatr Dent. 2015;8(2):157–162.
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- Gabriele Richard. Autosomal Recessive Congenital Ichthyosis. GeneReviews®.(https://www.ncbi.nlm.nih.gov/books/NBK1420/). Last Update: May 18, 2017.