Autosomal dominant lamellar ichthyosis

Clinical and genetic investigation of ichthyosis in familial and sporadic cases in south of Tunisia: genotype-phenotype correlation

Background

Ichthyosis is a heterogeneous group of Mendelian cornification disorders that includes syndromic and non-syndromic forms. Autosomal Recessive Congenital Ichthyosis (ARCI) and Ichthyosis Linearis Circumflexa (ILC) belong to non-syndromic forms. Syndromic ichthyosis is rather a large group of heterogeneous diseases. Overlapping phenotypes and genotypes between these disorders is a major characteristic. Therefore, determining the specific genetic background for each form would be necessary.

Methods

A total of 11 Tunisian patients with non-syndromic (8 with ARCI and 2 with ILC) and autosomal syndromic ichthyosis (1 patient) were screened by a custom Agilent HaloPlex multi-gene panel and the segregation of causative mutations were analyzed in available family members.

Results

Clinical and molecular characterization, leading to genotype–phenotype correlation in 11 Tunisian patients was carried out. Overall, we identified 8 mutations in 5 genes. Thus, in patients with ARCI, we identified a novel (c.118T > C in NIPAL4) and 4 already reported mutations (c.534A > C in NIPAL4; c.788G > A and c.1042C > T in TGM1 and c.844C > T in CYP4F22). Yellowish severe keratoderma was found to be associated with NIPAL4 variations and brachydactyly to TGM1 mutations. Two novel variations (c.5898G > C and c.2855A > G in ABCA12) seemed to be features of ILC. Delexon13 in CERS3 was reported in a patient with syndromic ichthyosis.

Conclusions

Our study further extends the spectrum of mutations involved in ichthyosis as well as clinical features that could help directing genetic investigation.

Clinico-epidemiological Study of Congenital Ichthyosis in a Tertiary Care Center of Eastern India

Background

Congenital ichthyoses comprises various specific genetic diseases and can range from mild to very severe presentation. Furthermore, these may be associated with various syndromes. There is scanty data regarding the demographic profile and clinical features of patients with congenital ichthyosis in India.

Aims and Objectives

The aim is to evaluate the epidemiology and clinical characteristics of various types of congenital ichthyoses.

Materials and Methods

The study was conducted for 1 year from April 2013 to March 2014. Patients were evaluated for epidemiological profile and clinical features.

Results

During the study of 1 year, 106 patients of congenital ichthyoses were identified. The most common of the various ichthyoses was ichthyosis vulgaris, followed by lamellar ichthyosis, X-linked recessive ichthyosis. One case of Netherton syndrome and one of ichthyosis hystrix were also identified.

Conclusion

Various types of congenital ichthyoses present with different clinical features which range from mild to severe. These present with significant psychological stress to both patients and their families. Furthermore, all these diseases have significant implications of transmission to their offspring.

Autosomal recessive congenital ichthyosis

The term autosomal recessive congenital ichthyosis (ARCI) refers to a group of rare disorders of keratinization classified as nonsyndromic forms of ichthyosis. This group was traditionally divided into lamellar ichthyosis (LI) and congenital ichthyosiform erythroderma (CIE) but today it also includes harlequin ichthyosis, self-healing collodion baby, acral self-healing collodion baby, and bathing suit ichthyosis. The combined prevalence of LI and CIE has been estimated at 1 case per 138 000 to 300 000 population. In some countries or regions, such as Norway and the coast of Galicia, the prevalence may be higher due to founder effects. ARCI is genetically highly heterogeneous and has been associated with 6 genes to date: TGM1, ALOXE3, ALOX12B, NIPAL4, CYP4F22, and ABCA12. In this article, we review the current knowledge on ARCI, with a focus on clinical, histological, ultrastructural, genetic, molecular, and treatment-related aspects.

Eyelid abnormalities in lamellar ichthyoses

PURPOSE

To describe eyelid abnormalities in lamellar ichthyoses (LI).

DESIGN

Retrospective observational case series.

PARTICIPANTS

Eight patients with classic LI and two patients with congenital ichthyosiform erythroderma.

METHODS

Results of eyelid and corneal examinations of 10 patients with LI were reviewed and analyzed with emphasis on the relationship between eyelid ectropion and corneal damage.

RESULTS

All patients presented with cicatricial lagophthalmos. Of the eight patients with classic LI, five had ectropion of the four eyelids, one had only lower ectropion, and two had no degree of ectropion. Two patients with congenital ichthyosiform erythroderma had distinct eyelid abnormalities, including madarosis and eyelash retraction. Loss of vision caused by corneal damage was found in three patients with classic LI. Of these three patients, two did not have upper eyelid ectropion.

CONCLUSIONS

Severe corneal damage can occur in LI even if there is no upper or lower eyelid ectropion.

The quantification of free sphingosine in the stratum corneum of patients with hereditary ichthyosis

Sphingosine is a long-chain base which provides the back-bone of all sphingolipid molecules. Free sphingosine is found in normal epidermis, especially in the stratum corneum. As a free molecule it may modify epidermal cell proliferation and differentiation through its inhibition of protein kinase C. Using a thin-layer chromatography technique we have demonstrated in vitro that the erythrodermic ichthyoses show significantly lower levels of stratum corneum sphingosine than the non-erythrodermic types. The exact in vivo significance of this finding is unclear, but free sphingosine may have an important role in determining the inflammatory component of the hereditary ichthyoses.

Autosomal dominant lamellar ichthyosis exhibits an abnormal scale lipid pattern

Autosomal dominant lamellar ichthyosis (ADLI) is a recently recognized genetic skin disorder. Clinically and histologically, it cannot be distinguished with certainty from the more frequent autosomal recessive lamellar ichthyosis (ARLI), which in itself may still be heterogeneous. By ultrastructural examination of ADLI a prominent transforming zone between the stratum granulosum and stratum corneum and lipid inclusions in the stratum corneum have been observed. Using sequential high-performance thin-layer chromatography, we studied the plantar scale lipid pattern of two patients, mother and daughter, affected with ADLI. We found a distinctive alteration in the relative composition of the scale lipid pattern characterized by excessive amounts of free fatty acids, triglycerides, elevated n-alkanes, reduced free sterols and decreased total ceramides. This scale lipid profile clearly differs from that of the erythrodermic and non-erythematous variants of ARLI and confirms that this disorder is a distinct entity of the heterogeneous group of lamellar ichthyoses.