Prenatal exclusion of harlequin ichthyosis; potential pitfalls in the timing of the fetal skin biopsy

Congenital Ichthyosis: Current Approaches to Prenatal Diagnoses

INTRODUCTION

Congenital ichthyosis represents a wide spectrum of diseases. This article reviews prenatal testing for ichthyosis.

METHODS

We used pubmed.ncbi.nlm.nih.gov to search for 38 types of congenital ichthyosis combined with 17 words related to prenatal testing.

RESULTS

Search resulted in 408 publications covering 13 types of ichthyoses and four types of tests.

DISCUSSION

Biochemical testing is diagnostic in trichothiodystrophy, but nonspecific in X-linked ichthyosis and Refsum syndrome. Except in X-linked ichthyosis, biochemical testing requires invasive procedures to obtain fetal skin biopsy, amniocytes, or chorionic villus samples. It is superior to histological and cytological examination of fetal skin biopsy or amniocytes because keratinization occurs later in pregnancy and microscopy cannot differentiate between ichthyosis types. Imaging is more acceptable due to noninvasiveness and routine use, although ultrasonography is operator-dependent, nonspecific, and captures abnormalities at late stage. Molecular tests are described in at-risk pregnancies but testing of free fetal DNA was not described.

Case Report: Novel rare mutation c.6353C > G in the ABCA12 gene causing harlequin ichthyosis identified by whole exome sequencing

BACKGROUND

Harlequin ichthyosis (HI) is a severe rare genetic disease that mainly affects the skin. Neonates with this disease are born with thick skin and large diamond-shaped plates covering most of their bodies. Affected neonates lose the ability to control dehydration and regulate temperature and are more susceptible to infections. They also face respiratory failure and feeding problems. These clinical symptoms are factors associated with high mortality rates of neonates with HI. Until now, there are still no effective treatments for HI patients and most patients die in the newborn period. Mutation in the ABCA12 gene, which encodes an adenosine triphosphate-binding cassette (ABC) transporter, has been demonstrated as the major cause of HI.

CASE PRESENTATION

In this study, we report the case who is one infant that was born prematurely at 32 gestational weeks with the whole body covered with thick plate-like scales of skin. The infant was severely infected with mild edema, multiple cracked skins full of the body, yellow discharge, and necrosis of fingers and toes. The infant was suspected to be affected by HI. Whole exome sequencing (WES) was performed as a tool for detecting the novel mutation in one prematurely born Vietnam infant with HI phenotype. And after that, the mutation was confirmed by the Sanger sequencing method in the patient and the members of his family. In this case, one novel mutation c.6353C > G (p.S2118X, Hom) in the ABCA12 gene, was detected in the patient. The mutation has not been reported in any HI patients previously. This mutation was also found in a heterozygous state in the members of the patient's family, including his parents, an older brother, and an older sister who are no symptoms.

CONCLUSIONS

In this study, we identified a novel mutation in a Vietnamese patient with HI by whole exome sequencing. The results for the patient and the members of his family will be helpful in understanding the etiology of the disease, diagnosing carriers, assisting in genetic counseling, and emphasizing the need for DNA-based prenatal screening for families with a history of the disease.

Harlequin ichthyosis: A case report and literature review

Harlequin ichthyosis is a rare autosomal recessive disorder occurring in 1: 3,000,000 birth characterized by thick keratin skin with a scaly appearance. Preterm deliveries, early, and consanguinity of marriage are some risk factors. Antenatal checkup of DNA for ABCA12 mutation helps in diagnosis but ultrasonography in places was not available.

Prenatal diagnosis of congenital harlequin ichthyosis with fetal MRI

Most of the fetal deformities are caused due to genetic abnormalities. Although magnetic resonance imaging (MRI) may be used to accurately diagnose these deformities, it has been reported that gene analysis is a more accurate diagnostic method. Harlequin ichthyosis (HI) or Ichthyosis fetalis (IF) is a rare and extremely severe hereditary skin disorder with autosomal recessive inheritance. The ultrasound features have been described well and the diagnosis can be made with a fair degree of confidence. However, the final diagnosis needs to be established by prenatal invasive tests. In the present study, we describe the diagnosis of HI in the third trimester on fetal MRI referred to our department with suspicion of anterior encephalocele which was later confirmed through postnatal genetic evaluation.

Harlequin fetus born from Consanguinity: A deleterious case report

Harlequin Ichthyosis (HI) is a dreadful skin disorder with steady rise of cases with prolonged survival. Harlequin fetus follows an autosomal recessive pattern with the incidence of 1in 300,000 live births. In the succeeding case report, a male child was born with keratinized and kaleidoscopic diamond pattern of skin suggestive of HI. He was born at 36th week of gestation from consanguineous marriage. The newborn remained under extensive intensive care in a tertiary care unit where he breathed his last on 11th day after birth. Prenatal diagnosis and genetic counseling is of vital importance due to the association of ABCA12 mutation with HI.

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.

Harlequin ichtyosis (harlequin fetus): case description

Harlequin ichtyosis was observed at a girl, who managed to survive till 4 months age. Results of postmortem examination were presented. Diagnostic criteria were described, issues of prenatal diagnostics and treatment opportunities are being discussed.

Harlequin ichthyosis: A medico legal case report & review of literature with peculiar findings in autopsy

Ichthyosis fetalis or Harlequin ichthyosis is an extremely severe and fatal hereditary skin disorder with an autosomal recessive inheritance. It is distinctive because of its remarkable clinical appearance which includes epidermal keratinization, hypoplasia of fingers or nails, malformation of ear and nose and incompatibility with life. This report describes a case of Harlequin ichthyosis along with detailed autopsy findings, which manifested the suspended animation in the early hours after delivery and showing a peculiar malformation of the cerebral hemispheres. To the best of the knowledge, this may be the first report of Harlequin ichthyosis in the forensic literature describing mal development of cerebral hemispheres and suspended animation in a case of Harlequin Ichthyosis.

Unusual protrusion of conjunctiva in two neonates with harlequin ichthyosis

Background

We present two patients who developed severe protrusion of the conjunctiva and chemosis secondary to Harlequin ichthyosis (HI).

Case Reports

Case 1 was a male infant diagnosed with HI who had parchment-like appearance and conjunctival protrusion with severe chemosis. Case 2 was a female infant on whom HI had been suspected before birth through ultrasonography. She showed thickened skin over the entire body and conjunctival protrusion with severe chemosis. For both cases, a vitamin A derivative was applied and the hyperkeratotic layer was peeled off every day. Great care was taken to sterilize and moisten the ocular surface. The conjunctival protrusion gradually improved and other systemic conditions were successfully treated. HI is a rare condition, but affected infants are surviving longer than previously and hence guidelines for ocular management are now required.

Conclusions

Gentle and patient debridement of the hyperkeratotic skin and moisturizing were important in treating the unusual conjunctival protrusion.

Expression of the keratinocyte lipid transporter ABCA12 in developing and reconstituted human epidermis

Serious defects in the epidermal keratinocyte lipid transporter ABCA12 are known to result in a deficient skin lipid barrier, leading to harlequin ichthyosis (HI). HI is the most severe inherited keratinizing disorder and is frequently fatal in the perinatal period. To clarify the role of ABCA12, ABCA12 expression was studied in developing human skin and HI lesions artificially reconstituted in immunodeficient mice. By immunofluorescent study, ABCA12 was expressed in the periderm of the early stage two-layered human fetal epidermis. After formation of a three-layered epidermis, ABCA12 staining was seen throughout the entire epidermis. ABCA12 mRNA expression significantly increased during human skin development and reached 62% of the expression in normal adult skin, whereas the expression rate of transglutaminase 1, loricrin, and kallikrein 7 remained low. We transplanted keratinocytes from patients with HI and succeeded in reconstituting HI skin lesions in immunodeficient mice. The reconstituted lesions showed similar changes to those of patients with HI. Our findings demonstrate that ABCA12 is highly expressed in fetal skin and suggest that ABCA12 may play an essential role under both the wet and dry conditions, including the dramatic turning point from a wet environment of the amniotic fluid to a dry environment after birth.

DNA-Based Prenatal Diagnosis of Harlequin Ichthyosis and Characterization of ABCA12 Mutation Consequences

Until the identification of ABCA12 as the causative gene, prenatal diagnosis (PD) for harlequin ichthyosis (HI) had been performed by electron microscopic observation of fetal skin biopsy samples. We report the first case of HI DNA-based PD. Direct sequence analysis of ABCA12 revealed that the deceased proband was a compound heterozygote for two novel mutations. The maternal nonsense mutation p.Ser1249Term likely leads to nonsense-mediated messenger RNA decay. The paternal mutation c.7436G>A affects the last codon of exon 50 and was expected to be a splice site mutation. For their third pregnancy, the parents requested PD. Direct sequence analysis of fetal genomic DNA from amniotic fluid cells at 17 weeks gestation revealed the fetus was a compound heterozygote for both mutations. The parents requested the pregnancy to be terminated. Analysis of ABCA12 transcripts of cultured keratinocytes from the abortus showed the presence of six abnormally spliced products from the allele carrying the splice site mutation. Four of them lead to premature termination codons whereas the two others produced shortened proteins missing 21 and 31 amino acids from the second ATP-binding cassette. This report provides evidence for residual ABCA12 expression in HI, and demonstrates the efficiency of early DNA-based PD of HI.