Chanarin-Dorfman Syndrome: A comprehensive review

[Translated article] ICHTHYOSIS: Clinical and Molecular Update. Part 2: Syndromic Ichthyosis. Diagnostic and Therapeutic Approach of Ichthyosis

Syndromic ichthyoses are a group of disorders whose genetic alterations impact both epidermal and non-epidermal tissues. Therefore, patients present symptoms in other organs. Most are extraordinary and, in some, ichthyosiform desquamation has been poorly described. Their patterns of inheritance are diverse; their extracutaneous clinical signs, heterogeneous; and the skin symptoms, highly variable, which hinders a proper clinical classification. Ichthyosis diagnosis starts with proper anamnesis, detailed physical examination, and detection of associated analytic and/or histologic findings. Genetic testing is indispensable, not only for diagnostic certainty, but also because understanding the molecular substrate for each patient is the first step towards finding an individualized therapeutic regimen. While it will almost invariably involve facilitating desquamation and maintaining skin hydration using topical exfoliants and emollients, recently, replacement therapies aiming at substituting the proteins and lipids specifically altered in each patient are being developed and gene therapy approaches with the ultimate goal of curing the disease are being assessed. In part 2 of this review, we will be updating the clinical and genetic findings of syndromic entities, ichthyosis diagnosis and treatment.

ICHTHYOSIS: Clinical and molecular update. Part 2: Syndromic ichthyosis. Diagnostic and therapeutic approach of ichthyosis

Syndromic ichthyoses are a group of disorders whose genetic alterations impact both epidermal and non-epidermal tissues. Therefore, patients present symptoms in other organs. Most are extraordinary and, in some, ichthyosiform desquamation has been poorly described. Their patterns of inheritance are diverse; their extracutaneous clinical signs, heterogeneous; and the skin symptoms, highly variable, which hinders a proper clinical classification. Ichthyosis diagnosis starts with proper anamnesis, detailed physical examination, and detection of associated analytic and/or histologic findings. Genetic testing is indispensable, not only for diagnostic certainty, but also because understanding the molecular substrate for each patient is the first step towards finding an individualized therapeutic regimen. While it will almost invariably involve facilitating desquamation and maintaining skin hydration using topical exfoliants and emollients, recently, replacement therapies aiming at substituting the proteins and lipids specifically altered in each patient are being developed and gene therapy approaches with the ultimate goal of curing the disease are being assessed. In part 2 of this review, we'll be updating the clinical and genetic findings of syndromic entities, ichthyosis diagnosis and treatment.

Using chanarin-dorfman syndrome patient fibroblasts to explore disease mechanisms and new treatment avenues

BACKGROUND

Chanarin-Dorfman syndrome (CDS) is a multisystemic autosomal recessive rare disorder. CDS is caused by variants in the abhydrolase domain containing 5 (ABHD5) encoding gene (CGI-58), which ultimately leads to excessive lipid storage, and therefore a high abundance of cellular lipid droplets (LDs). Although the molecular etiology of the disease was described many years ago, no treatment for CDS is currently available.

RESULTS

To further characterize the molecular basis of the disease and to uncover new treatment avenues, we used skin fibroblasts originating from a young patient diagnosed with CDS due to a homozygous nonsense mutation. We show that dysfunctional ABHD5 does not only affect LDs, but also influences other metabolic-related organelles; the mitochondria and peroxisomes. Additionally, we found that expressing functional ABHD5 in CDS patient cells reduced LD number. Finally, we developed and applied a high content-based drug repurposing screen based on a collection of ∼2500 FDA approved compounds, yielding several compounds that affected LD total area and size.

CONCLUSIONS

Our findings enhance the understanding of the dysfunction underlying CDS and propose new avenues for the treatment of CDS patients.

Anomalía de Jordans en síndrome de Chanarin-Dorfman

Objetivos

El síndrome de Chanarin-Dorfman es un síndrome raro de herencia autosómica recesiva cuya prevalencia no supera los 130 casos en el mundo.

Caso clínico

Paciente de 4 años afecto de síndrome ictiosiforme eritemato-descamativo generalizado desde los primeros días del nacimiento. En el informe de laboratorio destacó hipertransaminemia persistente en el tiempo. Entre otras pruebas complementarias, se realizó el frotis de sangre periférica (SP), revelando la presencia de múltiples vacuolas citoplasmáticas en el interior de los leucocitos polimorfonucleares (PMN) y plaquetas. Las lesiones ictiosiformes junto con la presencia de vacuolas lipídicas en los PMN de SP son signos compatibles con síndrome de Chanarin-Dorfman. El diagnóstico se confirmó mediante secuenciación genética.

Conclusiones

El síndrome de Chanarin-Dorfman está caracterizado por una mutación del gen CGI-58 , el cual está implicado en el catabolismo de los triglicéridos de cadena larga almacenados en gotas lipídicas citoplasmáticas. La anomalía de Jordans es un rasgo congénito caracterizado por la presencia de abundantes vacuolas en la serie granulocítica debido a defectos en el metabolismo lipídico. En este síndrome, los triglicéridos de cadena larga se depositan en los tejidos produciendo principalmente manifestaciones dermatológicas controlables mediante la restricción de los mismos en la dieta.

Jordans' anomaly in Chanarin-Dorfman syndrome

Objectives

Chanarin-Dorfman syndrome is a rare disease inherited in an autosomal recessive pattern whose prevalence does not exceed 130 cases worldwide.

Case presentation

A 4-year-old patient with generalized erythematous-desquamative ichthyosiform syndrome since birth. The main laboratory finding was persistent hypertransaminasemia. Supplementary studies included peripheral blood smear (PBS), which revealed the presence of multiple cytoplasmatic vacuoles in polymorphonuclear leukocytes (PMN) and platelets. Ichthyosiform lesions concomitant to the presence of lipid vacuoles in peripheral blood PMNs are signs of Chanarin-Dorfman syndrome. Diagnostic suspicion was confirmed by genetic sequencing.

Conclusions

Chanarin-Dorfman syndrome is characterized by a mutation in the CGI-58 gene. This gene is involved in the catabolism of long-chain triglycerides stored in cytoplasmic lipid droplets. Jordans' anomaly is a congenital alteration characterized by the presence of multiple vacuoles in the granulocytic series due to defective lipid metabolism. In this syndrome, long-chain triglycerides build up in tissues, thereby causing dermatological manifestations that are controllable through diet.

Cellular mechanisms of acute rhabdomyolysis in inherited metabolic diseases

Acute rhabdomyolysis (RM) constitutes a life-threatening emergency resulting from the (acute) breakdown of skeletal myofibers, characterized by a plasma creatine kinase (CK) level exceeding 1000 IU/L in response to a precipitating factor. Genetic predisposition, particularly inherited metabolic diseases, often underlie RM, contributing to recurrent episodes. Both sporadic and congenital forms of RM share common triggers. Considering the skeletal muscle's urgent need to rapidly adjust to environmental cues, sustaining sufficient energy levels and functional autophagy and mitophagy processes are vital for its preservation and response to stressors. Crucially, the composition of membrane lipids, along with lipid and calcium transport, and the availability of adenosine triphosphate (ATP), influence membrane biophysical properties, membrane curvature in skeletal muscle, calcium channel signaling regulation, and determine the characteristics of autophagic organelles. Consequently, a genetic defect involving ATP depletion, aberrant calcium release, abnormal lipid metabolism and/or lipid or calcium transport, and/or impaired anterograde trafficking may disrupt autophagy resulting in RM. The complex composition of lipid membranes also alters Toll-like receptor signaling and viral replication. In response, infections, recognized triggers of RM, stimulate increased levels of inflammatory cytokines, affecting skeletal muscle integrity, energy metabolism, and cellular trafficking, while elevated temperatures can reduce the activity of thermolabile enzymes. Overall, several mechanisms can account for RMs and may be associated in the same disease-causing RM.

Liver Transplant Outcome in Chanarin-Dorfman Syndrome: A Rare Lipid Storage Disease

Chanarin-Dorfman syndrome is a multisystem inherited metabolic disorder characterized by congenital ichthyosis and lipid droplet accumulation in various organs, including the liver, muscles, and skin. The accumulation of lipids in the liver can lead to cirrhosis, liver failure, and even hepatocellular carcinoma. Here, we present a 17-year-old girl who underwent a deceased donor liver transplant to treat uncompensated cirrhosis due to Chanarin-Dorfman syndrome. She underwent a successful liver transplant in January 2019 and has remained, to date, with a completely normal liver profile, without any posttransplant complications such as infection, rejection, and disease recurrence. There have been a few reported cases of liver transplants in Chanarin-Dorfman syndrome. This unique report presents the 5-year outcome of liver transplant in Chanarin-Dorfman syndrome and aims to improve knowledge about the specific treatment in these rare cases.

Four cases of Chanarin-Dorfman syndrome presenting with different types of erythrokeratoderma

Chanarin-Dorfman syndrome (CDS) is a multisystem autosomal recessive disorder due to variants of the ABHD5 gene, characterized by lipid vacuoles in the liver and leukocytes, and possible involvement of eyes, ears, skeletal muscle, and central nervous system. CDS may present with skin changes, most commonly congenital non- bullous ichthyosiform erythroderma, however erythrokeratoderma-like findings have been rarely reported in CDS patients. Herein, we report clinical, histopathological and genetic findings of four patients with CDS presenting with different clinical forms of erythrokeratoderma (three with progressive symmetric erythrokeratoderma-like features and one with erythrokeratoderma variabilis (EKV)-like features), including one patient with a novel mutation in ABHD5. Although the typical skin finding of CDS syndrome is reported as non-bullous congenital ichthyosiform erythroderma, CDS should also be in the differential diagnosis in patients with EKV-like lesions.

Navigating Surgical Challenges: Managing Juvenile Glaucoma in a Patient with Dorfman-Chanarin Syndrome

We report a surgically challenging case, in the context of a diagnosis of juvenile glaucoma refractory to drug therapy, multi-operated, known patient with congenital ichthyosis, part of Dorfman-Chanarin Syndrome (DCS), with a single functional eye. She is a young patient (54) and housewife in an urban environment known to have DCS and BE (both eyes), strong myopia, and congenital nystagmus. She initially underwent cataract surgery in 2015 and again in 2017. As of 2015, she was known to have juvenile glaucoma under maximal therapy. The important increases in pressure started in 2020 when the dermatological condition worsened (exacerbation of skin changes in the context of ichthyosis), the patient is in menopause, and presbyopia has set in. The glaucoma could no longer be controlled with medication and required serial surgery in both eyes (initially in the right eye in 2020 and in the left eye in 2023). The right eye showed a favorable evolution until 2024, when a second trabeculectomy became necessary, with a favorable evolution. Conclusions: To our knowledge, such a case has not been documented in the medical literature. Frequent monitoring of intraocular pressures and prompt treatment are required. It is a rare association, a very complicated case of managing a patient with refractory glaucoma and multiple associated ophthalmic and systemic pathologies. We are also dealing with a single functional eye, difficult to manage due to a thin sclera that has caused intraoperative difficulties, and the association of congenital nystagmus and strabismus.

Review article: Hepatic steatosis and its associations with acute and chronic liver diseases

BACKGROUND

Hepatic steatosis is a common finding in liver histopathology and the hallmark of metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease (NAFLD), whose global prevalence is rising.

AIMS

To review the histopathology of hepatic steatosis and its mechanisms of development and to identify common and rare disease associations.

METHODS

We reviewed literature on the basic science of lipid droplet (LD) biology and clinical research on acute and chronic liver diseases associated with hepatic steatosis using the PubMed database.

RESULTS

A variety of genetic and environmental factors contribute to the development of chronic hepatic steatosis or steatotic liver disease, which typically appears macrovesicular. Microvesicular steatosis is associated with acute mitochondrial dysfunction and liver failure. Fat metabolic processes in hepatocytes whose dysregulation leads to the development of steatosis include secretion of lipoprotein particles, uptake of remnant lipoprotein particles or free fatty acids from blood, de novo lipogenesis, oxidation of fatty acids, lipolysis and lipophagy. Hepatic insulin resistance is a key feature of MASLD. Seipin is a polyfunctional protein that facilitates LD biogenesis. Assembly of hepatitis C virus takes place on LD surfaces. LDs make important, functional contact with the endoplasmic reticulum and other organelles.

CONCLUSIONS

Diverse liver pathologies are associated with hepatic steatosis, with MASLD being the most important contributor. The biogenesis and dynamics of LDs in hepatocytes are complex and warrant further investigation. Organellar interfaces permit co-regulation of lipid metabolism to match generation of potentially toxic lipid species with their LD depot storage.

Two novel heterozygous exonic deletions lead to Chanarin-Dorfman syndrome in a patient with congenital ichthyosis, sensorineural hearing loss, and liver dysfunction

Chanarin-Dorfman syndrome is an autosomal recessively inherited disorder characterized by ichthyosis, sensorineural hearing loss, and hepatic dysfunction. We report on a 60-year-old female of Venezuelan descent who presented with congenital ichthyosis, progressive sensorineural hearing loss, and liver cirrhosis. We identify a heterozygous copy number deletion involving exon 1 and another heterozygous deletion involving exon 3 of the ABHD5 gene. Exon 2 is preserved. Both deletions were confirmed with RT-PCR. RNAseq from peripheral blood shows a reduction of ABHD5 expression overall and an absence of exon 3 expression, confirming the deleterious effects of the identified deletions. We present exonic deletions as a potentially common type of ABHD5 variation.

Chanarin-Dorfman Syndrome diagnosed at the stage of liver transplantation: A rare lipid storage disease

Chanarin-Dorfman Syndrome (CDS) is a rare lipid storage disease with ichthyosis, hepatomegaly, myopathy, neuropathy, deafness, and ocular findings. Here, we aim to present an elderly CDS case and highlight the new endocrinological findings. A 66-year-old male patient with cirrhosis was hospitalized for liver transplantation. We suspected Chanarin-Dorfman Syndrome with ichthyosis, fatty liver, and syndromic facial features with bilateral ectropion, deafness, and malocclusion. We showed the lipid droplets in neutrophils called patognomonic Jordans' anomaly. Homozygous c.47+1 G>A mutation in the ABHD5 (NM_016006.6) gene were detected by clinical exome sequencing. Out of <160 CDS cases in the literature, this is the second eldest CDS patient and first with adrenal insufficiency, parathyroid lipoadenoma and atrophic pancreas. Clinicians should be aware of CDS as a rare cause of fatty liver. We recommend a blood smear and genetic analyses in patients with severe ichtiosis, ectropion, deafness and multiple endocrinolgic disorders.

Cross-sectional nationwide epidemiologic survey on quality of life and treatment efficacy in Japanese patients with congenital ichthyoses

BACKGROUND

Congenital ichthyoses sometimes present with severe skin symptoms that significantly affect the patient's quality of life (QOL). Symptomatic treatments are the mainstay therapies, and their efficacy is limited and inadequate.

OBJECTIVE

To assess the disease severity and QOL in patients with congenital ichthyoses, and to investigate the effectiveness of current treatments.

METHODS

We conducted a questionnaire-based Japan-wide epidemiological survey of patients with congenital ichthyosis who received medical care from 1 January 2016-31 December 2020. Effectiveness of past and current treatments was assessed. The outcomes were the physician's assessment, disease severity assessed using the clinical ichthyosis score (CIS), and the disease burden estimated using the Dermatology Life Quality Index (DLQI), the Children's Dermatology Life Quality Index (CDLQI), and the Infants' Dermatitis Quality of Life Index.

RESULTS

One hundred patients with 14 ichthyosis subtypes from 47 institutes were included in the final analysis. The CDLQI score showed a positive correlation with CIS (rs = 0.59, p = 0.004), while the DLQI score showed no significant correlation (rs = 0.13, p = 0.33). All existing medications were effective for many patients. Etretinate improved QOL and reduced CIS, but side effects including bone growth retardation were reported. Decreased treatment willingness was observed in patients with very low and very high CIS.

CONCLUSION

QOL scores were found to correlate with CIS in children, but not in adults. Considering the adverse events, it is speculated that etretinate is not indicated for children with mild cases. Petrolatum was the most commonly used medication, even in patients who were reluctant to receive treatment.

Dorfman-Chanarin Syndrome with Renal Involvement: A Rare Case Report and Literature Review

Dorfman-Chanarin syndrome (DCS) is a rare autosomal recessive disease. It is a multisystemic disease in which renal involvement is uncommon. We report the case of a woman with nephrotic syndrome associated with DCS. A 36-year-old woman was referred to the nephrology department for edema with known history for DCS. On physical examination, she had ichthyosiform erythroderma with generalized scaly skinand ascites. The ophthalmologic examination revealed a cataract in the right eye. Abdominal ultrasound examination showed hepatomegaly and splenomegaly. Laboratory tests showed normal renal and liver function. The blood cell count showed pancytopenia. Immunologic exams showed the presence of anti-mitochondrial antibodies. Kidney biopsy showed mesangial proliferative glomerulonephritis with extensive lipid vacuoles in the tubular epithelial cells. Immunofluorescence study showed mesangial deposits of IgG, C3, kappa, and lambda. To the best of our knowledge, this is the first case of DCS with renal involvement reported in an adult.

Ichthyosis, cataracts, and motor delay in an infant: A case of Chanarin-Dorfman syndrome

Chanarin-Dorfman syndrome (CDS) is a rare, autosomal recessive disorder of impaired triacylglycerol catabolism leading to cytoplasmic deposition of triglycerides in various cell types. We describe the case of an 8-month-old boy with cataracts, strabismus, motor delays, and an ichthyosiform rash since birth. Genetic testing revealed a pathogenic variant of the ABHD5 gene, suggestive of CDS, and further workup demonstrated hepatic steatosis and myopathy. His ichthyosis improved with initiation of a diet low in very long-chain fatty acids and medium-chain fatty acid supplementation.

Chanarin-Dorfman Syndrome (CDS): A Rare Lipid Metabolism Disorder

Chanarin-Dorfman syndrome (CDS) is a rare medical condition that is inherited in an autosomal recessive pattern. In CDS, a comparative gene identification-58 gene mutation causes the accumulation of triglycerides in neutrophils, which can be observed as vacuoles on a peripheral smear. CDS patients present with a characteristic dermatological finding, ichthyosis, which is a non-bullous white scaling of the skin. Here, we describe a case report of a one-year-old boy who presented to the pediatric outpatient department (OPD) with chief complaints of peeling of the skin and ballooning of the abdomen since birth. Our patient had achieved all the developmental milestones pertaining to his age. Genetic testing was positive for heterozygous alleles in both parents.

Metabolic Myopathies in the Era of Next-Generation Sequencing

Metabolic myopathies are rare inherited disorders that deserve more attention from neurologists and pediatricians. Pompe disease and McArdle disease represent some of the most common diseases in clinical practice; however, other less common diseases are now better-known. In general the pathophysiology of metabolic myopathies needs to be better understood. Thanks to the advent of next-generation sequencing (NGS), genetic testing has replaced more invasive investigations and sophisticated enzymatic assays to reach a final diagnosis in many cases. The current diagnostic algorithms for metabolic myopathies have integrated this paradigm shift and restrict invasive investigations for complicated cases. Moreover, NGS contributes to the discovery of novel genes and proteins, providing new insights into muscle metabolism and pathophysiology. More importantly, a growing number of these conditions are amenable to therapeutic approaches such as diets of different kinds, exercise training protocols, and enzyme replacement therapy or gene therapy. Prevention and management-notably of rhabdomyolysis-are key to avoiding serious and potentially life-threatening complications and improving patients' quality of life. Although not devoid of limitations, the newborn screening programs that are currently mushrooming across the globe show that early intervention in metabolic myopathies is a key factor for better therapeutic efficacy and long-term prognosis. As a whole NGS has largely increased the diagnostic yield of metabolic myopathies, but more invasive but classical investigations are still critical when the genetic diagnosis is unclear or when it comes to optimizing the follow-up and care of these muscular disorders.

Ichthyosis

The ichthyoses are a large, heterogeneous group of skin cornification disorders. They can be inherited or acquired, and result in defective keratinocyte differentiation and abnormal epidermal barrier formation. The resultant skin barrier dysfunction leads to increased transepidermal water loss and inflammation. Disordered cornification is clinically characterized by skin scaling with various degrees of thickening, desquamation (peeling) and erythema (redness). Regardless of the type of ichthyosis, many patients suffer from itching, recurrent infections, sweating impairment (hypohidrosis) with heat intolerance, and diverse ocular, hearing and nutritional complications that should be monitored periodically. The characteristic clinical features are considered to be a homeostatic attempt to repair the skin barrier, but heterogeneous clinical presentation and imperfect phenotype-genotype correlation hinder diagnosis. An accurate molecular diagnosis is, however, crucial for predicting prognosis and providing appropriate genetic counselling. Most ichthyoses severely affect patient quality of life and, in severe forms, may cause considerable disability and even death. So far, treatment provides only symptomatic relief. It is lifelong, expensive, time-consuming, and often provides disappointing results. A better understanding of the molecular mechanisms that underlie these conditions is essential for designing pathogenesis-driven and patient-tailored innovative therapeutic solutions.

ABHD5-A Regulator of Lipid Metabolism Essential for Diverse Cellular Functions

The α/β-Hydrolase domain-containing protein 5 (ABHD5; also known as comparative gene identification-58, or CGI-58) is the causative gene of the Chanarin-Dorfman syndrome (CDS), a disorder mainly characterized by systemic triacylglycerol accumulation and a severe defect in skin barrier function. The clinical phenotype of CDS patients and the characterization of global and tissue-specific ABHD5-deficient mouse strains have demonstrated that ABHD5 is a crucial regulator of lipid and energy homeostasis in various tissues. Although ABHD5 lacks intrinsic hydrolase activity, it functions as a co-activating enzyme of the patatin-like phospholipase domain-containing (PNPLA) protein family that is involved in triacylglycerol and glycerophospholipid, as well as sphingolipid and retinyl ester metabolism. Moreover, ABHD5 interacts with perilipins (PLINs) and fatty acid-binding proteins (FABPs), which are important regulators of lipid homeostasis in adipose and non-adipose tissues. This review focuses on the multifaceted role of ABHD5 in modulating the function of key enzymes in lipid metabolism.

Case Report: Chanarin-Dorfman Syndrome: A Novel Homozygous Mutation in ABHD5 Gene in a Chinese Case and Genotype-Phenotype Correlation Analysis

The Chanarin-Dorfman syndrome (CDS) is a rare, autosomal recessively inherited genetic disease, whch is associated with a decrease in the lipolysis activity in multiple tissue cells. The clinical phenotype involves multiple organs and systems, including liver, eyes, ears, skeletal muscle and central nervous system. Mutations in ABHD5/CGI58 gene have been confirmed to be associated with CDS. We performed whole exome sequencing on a Chinese CDS patient with skin ichthyosis features mimicking lamellar ichthyosis, ectropion, sensorineural hearing loss, and lipid storage in peripheral blood neutrophils. A novel homozygous missense mutation (p.L154R) in ABHD5 gene was detected in this patient. Genotype-phenotype analysis in reported CDS patients revealed no particular correlation. Our findings further enrich the reservoir of ABHD5 mutations in CDS.

Alterations of Ultra Long-Chain Fatty Acids in Hereditary Skin Diseases-Review Article

The skin is a flexible organ that forms a barrier between the environment and the body's interior; it is involved in the immune response, in protection and regulation, and is a dynamic environment in which skin lipids play an important role in maintaining homeostasis. The different layers of the skin differ in both the composition and amount of lipids. The epidermis displays the best characteristics in this respect. The main lipids in this layer are cholesterol, fatty acids (FAs) and ceramides. FAs can occur in free form and as components of complex molecules. The most poorly characterized FAs are very long-chain fatty acids (VLCFAs) and ultra long-chain fatty acids (ULCFAs). VLCFAs and ULCFAs are among the main components of ceramides and are part of the free fatty acid (FFA) fraction. They are most abundant in the brain, liver, kidneys, and skin. VLCFAs and ULCFAs are responsible for the rigidity and impermeability of membranes, forming the mechanically and chemically strong outer layer of cell membranes. Any changes in the composition and length of the carbon chains of FAs result in a change in their melting point and therefore a change in membrane permeability. One of the factors causing a decrease in the amount of VLCFAs and ULCFAs is an improper diet. Another much more important factor is mutations in the genes which code proteins involved in the metabolism of VLCFAs and ULCFAs—regarding their elongation, their attachment to ceramides and their transformation. These mutations have their clinical consequences in the form of inborn errors in metabolism and neurodegenerative disorders, among others. Some of them are accompanied by skin symptoms such as ichthyosis and ichthyosiform erythroderma. In the following review, the structure of the skin is briefly characterized and the most important lipid components of the skin are presented. The focus is also on providing an overview of selected proteins involved in the metabolism of VLCFAs and ULCFAs in the skin.

Maternal Isodisomy of Chromosome 3 Combined with a De Novo Mutation in the ABHD5 Gene Causes Autosomal Recessive Chanarin-Dorfman Syndrome

Autosomal recessive Chanarin-Dorfman syndrome (CDS, MIM #275630) is defined as a neutral lipid storage disease with ichthyosis (NLSDI) due to an accumulation of lipid droplets in a variety of different tissues including liver and muscle cells, leucocytes, fibroblasts and nerve cells It is caused by biallelic mutations in the abhydrolase domain containing 5 gene (ABHD5, MIM *604780) which is localized on the short arm of chromosome 3. Here we report an 18 month-old girl in whom we have identified the homozygous ABHD5 mutation c.700C > T, p.(Arg234*). Since none of the parents carried this point mutation, parentage was confirmed by microsatellite marker analysis. Suspected uniparental disomy (UPD) was confirmed by microsatellite genotyping over the entire chromosome 3 and indicated a maternal origin. UPD is an extremely rare event that is not necessarily pathogenic, but may cause disease if the affected chromosome contains genes that are imprinted. Here we report the first case of Chanarin-Dorfman syndrome due to a de novo ABHD5 mutation in the maternal germ cell, combined with a maternal uniparental isodisomy of chromosome 3. This case demonstrates that genetic analysis of the patient and both parents is crucial to provide correct genetic counseling.