DSP missense variant in a Scottish Highland calf with congenital ichthyosis, alopecia, acantholysis of the tongue and corneal defects

Background Ichthyosis describes a localized or generalized hereditary cornification disorder caused by an impaired terminal keratinocyte differentiation resulting in excessive stratum corneum with the formation of more or less adherent scales. Ichthyosis affects humans and animals. Two rare bovine forms are reported, the severe harlequin ichthyosis and the less severe congenital ichthyosis, both characterized by a severe orthokeratotic lamellar hyperkeratosis. Results A 2-weeks-old purebred Scottish Highland calf was referred because of a syndrome resembling congenital ichthyosis. The clinical phenotype included diffuse alopecia and a markedly lichenified skin covered with large and excessive scales. Additionally, conjunctivitis and ulceration of the cornea were noted. Post-mortem examination revealed deep fissures in the diffusely thickened tongue and histopathological findings in the skin confirmed the clinical diagnosis. Whole-genome sequencing of the affected calf and comparison of the data with control genomes was performed. A search for private variants in known candidate genes for skin phenotypes including genes related with erosive and hyperkeratotic lesions revealed a single homozygous protein-changing variant, DSP: c.6893 C>A, or p.Ala2298Asp. The variant is predicted to change a highly conserved residue in the C-terminal plakin domain of the desmoplakin protein, which represents a main intracellular component of desmosomes, important intercellular adhesion molecules in various tissues including epidermis. Sanger sequencing confirmed the variant was homozygous in the affected calf and heterozygous in both parents. Further genotyping of 257 Scottish Highland animals from Switzerland revealed an estimated allele frequency of 1.2%. The mutant allele was absent in more than 4800 controls from various other cattle breeds. Conclusions This study represents the first report of combined lesions compatible with congenital ichthyosis, alopecia, acantholysis of the tongue and corneal defects associated with a DSP missense variant as the most likely underlying cause. To the best of our knowledge, this study is also the first report of a DSP-related syndromic form of congenital ichthyosis in domestic animals. The results of our study enable genetic testing to avoid the unintentional occurrence of further affected cattle. The findings were added to the Online Mendelian Inheritance in Animals (OMIA) database (OMIA 002243-9913).

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.

A RARE CASE OF HARLEQUIN ICHTHYOSIS SUCCESSFULLY TREATED WITH ACITRETIN: A CASE REPORT AND LITERATURE REVIEW

Harlequin Ichthyosis is the most serious congenital keratinization disorder. When the children are born, they are enveloped in thick horn armor. They are thick yellow horn plates that tear deeply when they dry out. In the most severe form, the children often die in the first few weeks of life. But there are also many milder courses, whereby there are obviously flowing transitions from collodion baby to harlequin ichthyosis. The skin condition later corresponds to that of a child with severe congenital ichthyosis (ARCI). Similar to the collodion baby, cases of harlequin ichthyosis should initially be cared for in the intensive care unit for newborns and require interdisciplinary therapy. Harlequin ichthyosis is caused by very special mutations in the ABCA12 gene. These mutations also have an impact on survival. If homozygous mutations are present, the prospects are worse than if the parents have heterozygous mutations. Homozygous mutations are often present when the parents are consanguineous.

Expanding the clinical phenotype associated with NIPAL4 mutation: Study of a Tunisian consanguineous family with erythrokeratodermia variabilis—Like Autosomal Recessive Congenital Ichthyosis

Erythrokeratodermia variabilis (EKV) is a rare disorder of cornification usually associated with dominant mutations in the GJB3 and GJB4 genes encoding connexins (Cx)31 and 30.3. Genetic heterogeneity of EKV has already been suggested. We investigated at the clinical and genetic level a consanguineous Tunisian family with 2 sisters presenting an autosomal recessive form of EKV to better characterize this disease. Mutational analysis initially screened the connexin genes and Whole-exome sequencing (WES) was performed to identify the molecular aetiology of the particular EKV phenotype in the proband. Migratory shaped erythematous areas are the initial presenting sign followed by relatively stable hyperkeratotic plaques are the two predominates characteristics in both patients. However, remarkable variability of morphological and dominating features of the disease were observed between patients. In particular, the younger sister (proband) exhibited ichthyosiform-like appearance suggesting Autosomal Recessive Congenital Ichthyosis (ARCI) condition. No causative mutations were detected in the GJB3 and GJB4 genes. WES results revealed a novel missense homozygous mutation in NIPAL4 gene (c.835C>G, p.Pro279Ala) in both patients. This variant is predicted to be likely pathogenic. In addition, in silico analysis of the mutated 3D domain structure predicted that this variant would result in NIPA4 protein destabilization and Mg2+ transport perturbation, pointing out the potential role of NIPAL4 gene in the development and maintenance of the barrier function of the epidermis. Taken togheter, these results expand the clinical phenotype associated with NIPAL4 mutation and reinforce our hypothesis of NIPAL4 as the main candidate gene for the EKV-like ARCI phenotype.

Harlequin fetus in a twin sibling: a rare case report

Objective: Ichthyosis is a heterogeneous group of disorders characterized by hereditary keratinization of the skin. Ichthyosis means “fish skin.” There are at least 20 different types of ichthyosis. Among these, Harlequin-type ichthyosis is a rare, but often fatal, special form of congenital ichthyosis. Rates are higher in certain populations with higher probability of inbreeding. Babies are born with parchment-paper-like transparent membrane covering the whole body. Complications such as dehydration, prematurity, sepsis, electrolyte imbalance, and pneumonia could occur, adversely affecting survival. Case(s): We presented an ichthyosis case born from a dizygotic pregnancy of a Syrian woman living as a refugee in Turkey. Despite all the medical procedures performed in the neonatal intensive care unit, the baby who was diagnosed with Harlequin type ichthyosis died on the second postpartum day. Conclusion: Few cases of ichthyosis in twins have been reported. It is very important to benefit from prenatal screening and genetic counseling in the early diagnosis of such inherited, rare and fatal diseases.

Harlequin Ichthyosis in a Filipino Newborn: Management Pearls in a Resource-limited Setting

Introduction. Harlequin ichthyosis (HI) is a rare type of autosomal recessive congenital ichthyosis. There are approximately 200 documented cases worldwide, with less than five published reports in the Philippines. Despite its rarity, current literature suggests a better prognosis for these patients. Case description. We describe a preterm male newborn who presented at birth enclosed in a thick hyperkeratotic armor-like scale plates with areas of fissures, with associated ectropion, conjunctiva dehiscence, and eclabium. The thickened encasement also covered the hands and feet, causing severe contractures. A diagnosis of harlequin ichthyosis was given based on the clinical features. The patient was managed through a multidisciplinary approach, including referral to the tele-ichthyosis platform of a US-based foundation for patients with ichthyosis. Thermoregulation, nutrition, and hydration were carefully managed. Bland emollients were applied generously following normal saline soaks to improve barrier protection. Acitretin was administered on day 2 of life to facilitate the desquamation of the thickened encasement. A marked decrease in erythema and the thickness of the hyperkeratotic skin, and reduced conjunctival dehiscence were noted after one week of therapy. However, the constrictions on the hands and feet showed bluish discoloration and signs of necrosis. Linear band excision was performed to release the constrictors. Despite aggressive management, the patient succumbed to sepsis on day 12 of life. Conclusion. Improved prognosis amongst HI patients is correlated with optimal quality of care regardless of resource limitations. A multidisciplinary approach and early administration of retinoids cannot be overemphasized. Linear band excision within the first week of life is suggested for constrictions on the extremities that do not improve with retinoids to avoid necrosis and autoamputation.

Variants in the PNPLA1 Gene in Families with Autosomal Recessive Congenital Ichthyosis Reveal Clinical Significance

The term autosomal recessive congenital ichthyosis (ARCI) is the subgroup of ichthyosis, which describes a highly heterogeneous group of genetic disorders of the skin characterized by cornification and defective keratinocytes differentiation associated with mutations in at least 14 genes including <i>PNPLA1</i>. To study the molecular basis of the Pakistani kindreds (A and B) affected by ARCI, whole-exome sequencing (WES) in the DNA samples of affected members was performed followed by Sanger sequencing of the candidate gene to hunt down the disease-causing sequence variant/s. WES data analysis led to the identification of a novel nonsense sequence variant (c.892C&#x3e;T; p.Arg298*, family A) and a recurrent missense variant (c.102C&#x3e;A; p.Asp34Glu, family B) in <i>PNPLA1</i> mapped to the ARCI locus in chromosome 6p21.31. Validation and cosegregation analysis of the variants in the remaining family members of the respective families were confirmed by Sanger sequencing. The current investigation expands the spectrum of <i>PNPLA1</i> mutations and helps establish the proper clinico-genetic diagnosis and correct genotype-phenotype correlation.