High prevalence of autosomal recessive congenital ichthyosis in a Mexican population caused by a new mutation in the TGM1 gene: epidemiological evidence of a founder effect

Inherited ichthyosis as a paradigm of rare skin disorders: Genomic medicine, pathogenesis, and management

Great advances have been made in the field of heritable skin disorders using next-generation sequencing (NGS) technologies (ie, whole-genome sequencing, whole-exome sequencing, whole-transcriptome sequencing, and disease-targeted multigene panels). When NGS first became available, the cost and lack of access to these technologies were limiting factors; however, with decreasing sequencing costs and the expanding knowledge base of genetic skin diseases, fundamental awareness of NGS has become prudent. The heritable ichthyoses comprise a genotypically and phenotypically heterogeneous group of monogenic keratinization disorders characterized by persistent scaling, with at least 55 distinct genes currently implicated in causing nonsyndromic and syndromic forms of the disease. By providing a simplified overview of available NGS techniques and applying them in the context of ichthyosis, one of the most common genodermatoses, we hope to encourage dermatologists to offer, when appropriate, genetic testing earlier in patients with unsolved presentations. With the aid of NGS, dermatologists can provide diagnostic certainty in cases of suspected genodermatoses and offer potentially life-changing genome-guided and targeted therapies as they become available.

Advances in the treatment of autosomal recessive congenital ichthyosis, a look towards the repositioning of drugs

Autosomal recessive congenital ichthyoses (ARCI) are a skin pathology due to genetic causes characterized by a variable degree of desquamation, accompanied by erythema. The degree of symptoms is variable, different altered genes are involved, and the symptoms drastically affect patients' quality of life. Topical treatments are a first-choice strategy due to their ease of application and cost; however, enteral administration of retinoids offers greater efficacy, although with certain limitations. Despite the treatment alternatives, ARCI will persist throughout life, disabling people. Therefore, the search for new treatments always remains necessary. Especially repositioning drugs could be a short-term alternative to new affordable treatments for patients. Taking advantage of extensive knowledge of known drugs or biologics could ensure more accessible and possibly lower-cost treatments. This review briefly and concisely addresses possible repositioning strategies with drugs and biologics for ichthyosis.

High TGM1 Allelic Heterogeneity causing Lamellar ichthyosis in a small geographic area in South Mexico: Another Example of the "Réunion Paradox"

Lamellar ichthyosis (LI) is an autosomal recessive congenital ichthyosis characterized by generalized dry skin and severe scaling. It is caused by biallelic mutations in the TGM1 gene, however molecular data from non-Caucasian populations are limited. Results of genetic-molecular analysis of a group of LI pedigrees originating from two close small populations from south Mexico are presented. LI affected individuals belonging to 9 apparently unrelated families were studied. Exome sequencing or Sanger sequencing in probands from each family was carried out. Furthermore, DNA from 294 unaffected subjects from one of the communities were Sanger sequenced to determine the carrier frequency of the c.427C > T TGM1 variant. Five different TGM1 pathogenic variants, either in homozygous or in compound heterozygous state, were demonstrated in affected subjects. The two most common variants were c.427C > T (p.Arg143Cys) and c.1159+1G > T. A novel c.1645+1G > T TGM1 pathogenic allele was recognized. Carrier frequency analysis identified a total of 23 individuals heterozygous for the c.427C > T variant, predicting a prevalence of 78 carriers per 1000 inhabitants in the community. A high TGM1 allelic heterogeneity with 5 different LI-causing alleles in a limited geographic area was demonstrated. While the occurrence of homozygosity for a founder mutation is expected in small populations with high frequency of a particular autosomal recessive disorder, the occurrence of multiple pathogenic alleles has been previously described, a situation known as the Reúnion paradox. Our results expand the current knowledge of the mutational spectrum of TGM1-linked LI.

High Levels of Anxiety, Depression, Risk of Suicide, and Implications for Treatment in Patients with Lamellar Ichthyosis

Lamellar ichthyosis (LI) is a genodermatosis that injures the structure and function of the skin, affecting the appearance and self-esteem of patients, which may seriously impair their mental health and quality of life. In the present study, we determined anxiety, depression, and suicidal risk levels in patients with LI through the Beck anxiety and depression inventories (BAI and DBI-II, respectively) and the SAD PERSONS scale (SPS). We observed that anxiety, depression, and suicidal ideation were strongly associated with the LI (Cramér's V = 0.429, 0.594, and 0.462, respectively). Furthermore, patients with LI showed a significant increase in the scores of anxiety, depression, and suicidal risk (p = 0.011, <0.001, and 0.001, respectively) compared to individuals without the disease. Additionally, the suicide risk increased even more in patients who presented comorbidity of anxiety and depression than in patients who presented only anxiety or depression (p = 0.02). Similarly, the increase in the BAI scores correlated with the score observed on the SPS. Our results indicate that patients with LI have higher levels of anxiety and depression compared to individuals without the disease, which could be associated with suicidal risk. Therefore, the collaborative involvement of skin and mental health professionals is necessary to manage patients with LI appropriately. We believe that psychiatric studies and individual evaluations must be performed in LI patients to determine a treatment that, in addition to reducing skin symptoms, focuses on reducing the levels of depression and anxiety and improving the quality of life to reduce the risk of suicide.

Alterations in mental health and quality of life in patients with skin disorders: a narrative review

The presence of lesions in visible areas of skin may cause emotional troubles in patients, including low self-worth, embarrassment, sorrow, and social isolation. Those alterations may predispose to psychiatric disorders such as anxiety, depression, and even suicidal ideation, severely affecting patients' health state and quality of life (QoL). In this article, we focus on dermatologic patients that present with secondary mental health alterations. Thus, we offer a detailed description of mental disorders observed in patients with acne vulgaris, atopic dermatitis, psoriasis, ichthyosis, vitiligo, and hidradenitis suppurativa. Moreover, we point out the relationship between the severity of the cutaneous symptoms with mental illnesses and QoL decline. Our objective was to highlight the importance of mental health care for patients with skin diseases. The impact of skin alterations on the mental health of dermatological patients should be a central concern. Likewise, the timely identification and treatment of mental disorders are essential for the comprehensive management of these skin diseases.

Report of a Novel ALOX12B Mutation in Self-Improving Collodion Ichthyosis with an Overview of the Genetic Background of the Collodion Baby Phenotype

Collodion baby is a congenital, transient phenotype encountered in approximately 70–90% of autosomal recessive congenital ichthyosis and is an important entity of neonatal erythroderma. The clinical outcome after this severe condition is variable. Genetic mutations of components of the epidermal lipoxygenase pathway have been implicated in the majority of self-improving collodion ichthyosis (SICI). In SICI, the shedding of the collodion membrane reveals clear skin or only mild residual manifestation of ichthyosis. Here we report the case of a girl born with a severe form of collodion baby phenotype, whose skin almost completely cleared within the first month of life. At the age of 3 years, only mild symptoms of a keratinization disorder remained. However, the severity of erythema and scaling showed mild fluctuations over time. To objectively evaluate the skin changes of the patient, we assessed the ichthyosis severity index. Upon sequencing of the ALOX12B gene, we identified a previously unreported heterozygous nonsense mutation, c.1607G>A (p.Trp536Ter) with the recurrent, heterozygous mutation c.1562A>G (p.Tyr521Cys). Thereby, our findings expand the genotypic spectrum of SICI. In addition, we summarize the spectrum of further genetic diseases that can present at birth as collodion baby, in particular the SICI.

Increased risk of depression and impairment in quality of life in patients with lamellar ichthyosis

Lamellar ichthyosis (LI) is a genetic skin disorder characterized by dark brown scales, palmoplantar hyperkeratosis, pain, and itching. LI severity could have implications in psychological aspects, causing depression and impairment in the quality of life (QoL) of patients. In this study, we used the Congenital Ichthyosis Severity Index, the Depression Beck Inventory-II (DBI-II), and the Dermatologic Life Quality Index (DLQI) to assess severity, level of depression, and impairment in QoL in a group of patients with LI. We observed that the majority of the patients presented a high severity level concerning the presence of scales (57.7%), while for erythema and alopecia, the severity was less 80% of the analyzed patients presented depression, while only 20.8% of individuals of the control group presented it (P < .001, OR = 15.2). While for QoL, only 4.3% of the patients did not exhibit any impairment. Finally, the increase in the score obtained in DBI-II was correlated with the DLQI score (rs = 0.663, P = .0014). Our results suggest that patients with LI have an increased risk of suffering depression and impairment in their QoL; thus, the management of their disease should be performed from a multidisciplinary perspective to improve the global aspects of their lives.

Autosomal Recessive Congenital Ichthyosis and Steroid-Resistant Nephrotic Syndrome due to Homozygous Mutation in the ALOX12B gene: A Novel Association with Review of Literature

Nephrotic syndrome (NS) associated with autosomal recessive congenital ichthyosis (ARCI) is a rare association. In this article, we described a 4-year-old boy with steroid-resistant NS (SRNS) who had a history of ichthyotic skin lesions since birth. Renal biopsy revealed focal segmental glomerulosclerosis (tip variant). The skin biopsy was consistent with the findings of ichthyosis. Next-generation sequencing revealed a homozygous pathogenic variant (c.1625_1626del) in the exon 12 of the ALOX12B gene, confirming the diagnosis of ARCI2. The ALOX12B gene belongs to the lipoxygenase family and has a pivotal role in the formation of lipid layers in the epidermis. Leukotrienes have a counter-regulatory effect within the inflamed glomeruli, which influences the vascular tone and glomerular basement membrane permeability, that can be implicated in the pathogenesis of the NS. This child is currently in remission, on tacrolimus and low-dose prednisolone, with emollients and is on regular follow-up. SRNS associated with congenital ichthyosis secondary to a mutation in the ALOX12B gene has never been reported so far. The knowledge regarding this novel association will help the treating physicians in diagnosing this condition early, which will enable proper genetic counseling and prognostication of the disease to the family.