Depletion of alcohol (hexanol) dehydrogenase activity in the epidermis and jejunal mucosa in Sjögren-Larsson syndrome

Novel ALDH3A2 mutations in structural and functional domains of FALDH causing diverse clinical phenotypes in Sjögren-Larsson syndrome patients

Mutations in ALDH3A2 cause Sjögren-Larsson syndrome (SLS), a neuro-ichthyotic condition due to the deficiency of fatty aldehyde dehydrogenase (FALDH). We screened for novel mutations causing SLS among Indian ethnicity, characterized the identified mutations in silico and in vitro, and retrospectively evaluated their role in phenotypic heterogeneity. Interestingly, asymmetric distribution of nonclassical traits was observed in our cases. Nerve conduction studies suggested intrinsic-minus-claw hands in two siblings, a novel neurological phenotype to SLS. Genetic testing revealed five novel homozygous ALDH3A2 mutations in six cases: Case-1-NM_000382.2:c.50C>A, NP_000373.1:p.(Ser17Ter); Case-2-NM_000382.2:c.199G>T, NP_000373.1:p.(Glu67Ter); Case-3-NM_000382.2:c.1208G>A, NP_000373.1:p.(Gly403Asp); Case-4-NM_000382.2:c.1325C>T, NP_000373.1:p.(Pro442Leu); Case-5 and -6 NM_000382.2:c.1349G>A, NP_000373.1:p.(Trp450Ter). The mutations identified were predicted to be pathogenic and disrupt the functional domains of the FALDH. p.(Pro442Leu) at the C-terminal α-helix, might impair the substrate gating process. Mammalian expression studies with exon-9 mutants confirmed the profound reduction in the enzyme activity. Diminished aldehyde-oxidizing activity was observed with cases-2 and 3. Cases-2 and 3 showed epidermal hyperplasia with mild intracellular edema, spongiosis, hypergranulosis, and perivascular-interstitial lymphocytic infiltrate and a leaky eosinophilic epidermis. The presence of keratin-containing milia-like lipid vacuoles implies defective lamellar secretion with p.(Gly403Asp). This study improves our understanding of the clinical and mutational diversity in SLS, which might help to fast-track diagnostic and therapeutic interventions of this debilitating disorder.

Sjogren-Larsson syndrome associated hypermelanosis

BACKGROUND/OBJECTIVES

Sjogren - Larsson syndrome (SLS) is a rare autosomal recessive disease of the mutation ALDH3A2 that identifies a part of fatty acids for fatty aldehyde dehydrogenase: NAD-oxidoreductase enzyme complex. This study aimed to access variant ALDH3A2 gene coded for FALDH and products regulating pathogenic melanogenesis owing to increased oxidative stress and reactive oxygen species resulting in DNA harm in SLS. By turning them into fatty acids, FALDH avoids the accumulation of toxic fatty aldehydes. The mutation results in the accumulation of aldehyde-modified lipids or fatty alcohols that may interfere with skin and brain function.

METHODS

In Nov 2018, we performed a literature search in PubMed for clinical studies, clinical trials, case reports, controlled trials, randomized controlled trials, and systemic reviews. The search terms we used were "SJOGREN-LARSSON SYNDROME" AND "HYPERMELANNOSIS" OR "FALDH" (from 1985). The search resulted in 1,289 articles, out of these 95 articles met our inclusion exclusion criteria. Our inclusion criteria included relevant original articles relevant, critical systemic reviews, and crucial referenced articles, ex-clusion criteria included duplicates and articles not published in English language.

RESULTS

Toxicity of long-chain aldehydes to FALDH-deficient cells owing to accumulation under the profound epidermis layer improves oxidative stress in the cell resulting in keratinocyte hyperproliferation.

CONCLUSION

While it continues to be determined whether accumulated fatty alcohol and fatty aldehydes obtained from ether glycerolipids and sphingolipids improve the susceptibility of melanocytes and their element accountable for skin hyperpigmentation to biological colour.

Inherited ichthyosis: Syndromic forms

Among diseases that cause ichthyosis as one of the symptoms, there are some diseases that induce abnormalities in organs other than the skin. Of these, diseases with characteristic signs are regarded as syndromes. Although these syndromes are very rare, Netherton syndrome, Sjögren-Larsson syndrome, Conradi-Hünermann-Happle syndrome, Dorfman-Chanarin syndrome, ichthyosis follicularis, atrichia and photophobia (IFAP) syndrome, and Refsum syndrome have been described in texts as representative ones. It is important to know the molecular genetics and pathomechanisms in order to establish an effective therapy and beneficial genetic counseling including a prenatal diagnosis.

Fatty aldehyde and fatty alcohol metabolism: review and importance for epidermal structure and function

Normal fatty aldehyde and alcohol metabolism is essential for epidermal differentiation and function. Long-chain aldehydes are produced by catabolism of several lipids including fatty alcohols, sphingolipids, ether glycerolipids, isoprenoid alcohols and certain aliphatic lipids that undergo α- or ω-oxidation. The fatty aldehyde generated by these pathways is chiefly metabolized to fatty acid by fatty aldehyde dehydrogenase (FALDH, alternately known as ALDH3A2), which also functions to oxidize fatty alcohols as a component of the fatty alcohol:NAD oxidoreductase (FAO) enzyme complex. Genetic deficiency of FALDH/FAO in patients with Sjögren-Larsson syndrome (SLS) results in accumulation of fatty aldehydes, fatty alcohols and related lipids (ether glycerolipids, wax esters) in cultured keratinocytes. These biochemical changes are associated with abnormalities in formation of lamellar bodies in the stratum granulosum and impaired delivery of their precursor membranes to the stratum corneum (SC). The defective extracellular SC membranes are responsible for a leaky epidermal water barrier and ichthyosis. Although lamellar bodies appear to be the pathogenic target for abnormal fatty aldehyde/alcohol metabolism in SLS, the precise biochemical mechanisms are yet to be elucidated. Nevertheless, studies in SLS highlight the critical importance of FALDH and normal fatty aldehyde/alcohol metabolism for epidermal function. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. Guest Editors: Kenneth R. Feingold and Peter Elias.

The role of fatty aldehyde dehydrogenase in epidermal structure and function

The epidermal water barrier resides in the stratum corneum (SC) and is dependent on a highly organized network of multi-lamellar membranes comprised of a critical lipid composition. The SC membranes are formed from precursor membranes packaged in cytoplasmic lamellar bodies in the stratum granulosum and delivered to the SC by exocytosis. An abnormal lipid composition of the SC membranes often results in a disrupted water barrier and the clinical appearance of ichthyosis. This cutaneous feature is characteristic of Sjögren-Larsson syndrome (SLS), an inborn error of lipid metabolism caused by deficiency of fatty aldehyde dehydrogenase (FALDH). The contribution of FALDH to normal epidermal function has become increasingly evident with the recognition that this enzyme has an essential role in metabolism of several lipids, including fatty aldehydes and alcohols, ether glycerolipids, isoprenoid alcohols and certain lipids that undergo ω-oxidation, such as leukotriene B4 and very long-chain fatty acids. In the absence of FALDH, the skin produces lamellar bodies that are empty, lack their surrounding vesicle membranes or contain granular contents rather then the usual cargo membranes. These defective organelles also have impaired exocytosis, which results in structurally abnormal, deficient multi-lamellar membranes in the SC and a leaky water barrier. Although the exact biochemical mechanism for the cutaneous pathology is still unclear, studies in SLS demonstrate the critical importance of FALDH for normal epidermal structure and function.

Ichthyosis in Sjögren-Larsson syndrome reflects defective barrier function due to abnormal lamellar body structure and secretion

Sjögren-Larsson syndrome is a genetic disease characterized by ichthyosis, mental retardation, spasticity and mutations in the ALDH3A2 gene coding for fatty aldehyde dehydrogenase, an enzyme necessary for oxidation of fatty aldehydes and fatty alcohols. We investigated the cutaneous abnormalities in 9 patients with Sjögren-Larsson syndrome to better understand how the enzymatic deficiency results in epidermal dysfunction. Histochemical staining for aldehyde oxidizing activity was profoundly reduced in the epidermis. Colloidal lanthanum perfusion studies showed abnormal movement of tracer into the extracellular spaces of the stratum corneum consistent with a leaky water barrier. The barrier defect could be attributed to the presence of abnormal lamellar bodies, many with disrupted limiting membranes or lacking lamellar contents. Entombed lamellar bodies were present in the cytoplasm of corneocytes suggesting blockade of lamellar body secretion. At the stratum granulosum-stratum corneum interface, non-lamellar material displaced or replaced secreted lamellar membranes, and in the stratum corneum, the number of lamellar bilayers declined and lamellar membrane organization was disrupted by foci of lamellar/non-lamellar phase separation. These studies demonstrate the presence of a permeability barrier abnormality in Sjögren-Larsson syndrome, which localizes to the stratum corneum interstices and can be attributed to abnormalities in lamellar body formation and secretion.

Sjögren-Larsson syndrome: molecular genetics and biochemical pathogenesis of fatty aldehyde dehydrogenase deficiency

Sjögren-Larsson syndrome (SLS) is an inherited neurocutaneous disorder caused by mutations in the ALDH3A2 gene that encodes fatty aldehyde dehydrogenase (FALDH), an enzyme that catalyzes the oxidation of fatty aldehyde to fatty acid. Affected patients display ichthyosis, mental retardation and spastic diplegia. More than 70 mutations in ALDH3A2 have been discovered in SLS patients including amino acid substitutions, deletions, insertions and splicing errors. Most mutations are private, but several common mutations reflect founder effects, consanguinity or recurrent mutational events. FALDH oxidizes fatty aldehyde substrates arising from metabolism of fatty alcohols, leukotriene B4, ether glycerolipids and other potential sources such as sphingolipids. The pathogenesis of the cutaneous and neurologic symptoms is thought to result from abnormal lipid accumulation in the membranes of skin and brain; the formation of aldehyde Schiff base adducts with amine-containing lipids or proteins; or defective eicosanoid metabolism. Therapeutic approaches are being developed to target specific metabolic defects associated with FALDH deficiency or to correct the genetic defect by gene transfer.

Restoration of fatty aldehyde dehydrogenase deficiency in Sjögren-Larsson syndrome

Sjögren-Larsson syndrome (SLS) is an autosomal recessive neurocutaneous disorder caused by mutation in the ALDH3A2 gene that codes for human fatty aldehyde dehydrogenase (FALDH). Sjögren-Larsson syndrome patients lack FALDH, which catalyzes the oxidation of long-chain aliphatic aldehydes to fatty acids. The impaired FALDH activity leads to congenital ichthyosis, mental retardation and spasticity. The current lack of treatment is an impetus to develop gene therapy strategies by introducing functional FALDH into defective cells. We delivered human FALDH into keratinocytes of SLS patients using recombinant adeno-associated virus-2 vectors. Transduction of SLS keratinocytes resulted in an augmentation of FALDH activity comparable to phenotypically normal heterozygous carriers. Toxicity of long-chain aldehydes for FALDH-deficient cells decreased almost to the level of unaffected keratinocytes. Three-dimensional culture of corrected SLS keratinocytes revealed an ameliorated FALDH expression. These studies demonstrate the restoration of FALDH in human SLS cells supporting the concept of gene therapy as a potential future treatment option for SLS.

Inherited ichthyoses: a review of the histology of the skin

The histology of skin biopsies from 46 cases of different forms of congenital ichthyosis was reviewed. Sections were examined for hyperkeratosis, follicular keratosis, appearance of the granular layer, epidermal thickness, tonofilament clumps, epidermal vacuolation, spongiosis, bullae and dyskeratosis, appearance of the basal layer, inflammation, mitoses, and adnexae. A detailed description of the histological features of each type of ichtnyosis studied is presented. Some ichthyoses can be recognized on routine hematoxylin and eosin staining (bullous ichthyosiform erythroderma, Netherton's syndrome, and neutral lipid storage disease); some forms require frozen sections to demonstrate fat (neutral lipid storage disease) or enzyme activity (Sjögren-Larsson syndrome). Protein electrophoresis and enzymology are necessary for X-linked recessive ichthyosis. A close liaison with the clinicians is essential for the diagnosis of all types of ichthyosis, and combined studies including routine histopathology, electron microscopy, and frozen sections may be required for the diagnosis.

Confirmation of linkage of Sjögren-Larsson syndrome to chromosome 17 in families of different ethnic origins

Linkage analysis in two consanguineous pedigrees of Pakistani and English origin and one further Indian family in which affected subjects have Sjögren-Larsson syndrome (SLS) showed linkage to chromosome 17. Linkage of SLS to D17S783 and D17S805 has been reported in Swedish pedigrees, but since those data were generated from a single ethnic group originating from a common ancestor, there remained the question of whether this disease is genetically heterogeneous. This report confirms the linkage in non-Swedish pedigrees and, therefore, provides evidence to support a single locus for SLS.

Sjögren-Larsson syndrome is caused by mutations in the fatty aldehyde dehydrogenase gene

Sjögren-Larsson syndrome (SLS) is an inherited neurocutaneous disorder characterized by mental retardation, spasticity and ichthyosis. SLS patients have a profound deficiency in fatty aldehyde dehydrogenase (FALDH) activity. We have now cloned the human FALDH cDNA and show that it maps to the SLS locus on chromosome 17p11.2. Sequence analysis of FALDH amplified from fibroblast mRNA and genomic DNA from 3 unrelated SLS patients reveals distinct mutations, including deletions, an insertion and a point mutation. The cloning of FALDH and the identification of mutations in SLS patients opens up possibilities for developing therapeutic approaches to ameliorate the neurologic and cutaneous symptoms of the disease.

Patterns of gene expression along the crypt-villus axis in mouse jejunal epithelium

BACKGROUND

There is considerable interest in gene expression along the crypt-villus axis of the small intestinal epithelium, particularly in the identification of genes expressed in intestinal crypts.

METHODS

In an attempt to identify crypt-expressed genes, single-stranded cDNA made from normal mouse jejunal epithelium was used in subtractive hybridization against single-stranded cDNA from epithelium from which crypt cells were depleted by 2,000 rads of gamma irradiation. Partial DNA sequence and in situ hybridization of 72 resulting clones were determined.

RESULTS

The sequence of 45 clones matched previously published genes. Gene expression patterns fell into three categories: expression throughout the crypt-villus axis, expression restricted to the villus, and expression restricted to the crypt. Clones in the first two categories could be further divided into three subgroups: those with uniform expression, those with an increasing gradient of expression, and those with a decreasing gradient of expression along the crypt-villus axis. Twenty two clones showed a stronger expression in crypt and lower villus cells, four of these were differentially localized to the crypt. Two of the crypt localized clones were uniformly expressed throughout the crypt, expression of one was stronger in the lower crypt, and expression of the remaining clone was enhanced Paneth cells. We report the full-length cDNA sequence of the Paneth-cell-enhanced clone.

CONCLUSIONS

The screen isolated crypt-expressed genes that may prove useful tools in the study of crypt biology. In a companion report, we characterize one of the crypt clones.

Cerebral MRI and spectroscopy in Sjögren-Larsson syndrome: case report

We report MRI and MRS of the brain in a patient with Sjögren-Larsson syndrome (SLS) in whom fatty alcohol oxidoreductase (FAO) deficiency has been verified. MRI showed periventricular lesions, high intensity on T2-weighted and low intensity on T1-weighted images at trigones of the lateral ventricles. 1H-MRS of these lesions revealed high lipid and low N-acetyl aspartate peaks. We presume such lipids in periventricular lesions with high T2 signal may be pathognomonic of SLS.

Quantification of stratum corneum ceramides and lipid envelope ceramides in the hereditary ichthyoses

Ceramides (sphingolipids) are the main polar lipids of the stratum corneum and play an important role in skin barrier function, cell adhesion and epidermal differentiation. In view of the function of ceramides in normal skin, this study aimed to assess their levels in patients with various types of hereditary ichthyosis, in which epidermal homeostasis is markedly abnormal. Stratum corneum samples were collected from 80 patients and 23 normal controls, and the intercellular and lipid envelope ceramides were analysed by high-performance thin-layer chromatography. The covalently bound ceramides (ceramides A and B) of the lipid envelope were present in all patients studied, and showed no significant differences from control samples. Total ceramides (ceramides 1-6) were decreased in bullous ichthyosiform erythroderma, which is presumably a secondary phenomenon similar to that seen in patients with atopic dermatitis. Patients with non-erythrodermic lamellar ichthyosis showed a marked decrease in levels of the important acylceramide, ceramide 1, whereas those with other types of autosomal recessive ichthyosis (limited lamellar ichthyosis and non-bullous ichthyosiform erythroderma) had mean levels similar to the controls. Ceramide 1 deficiency may therefore define a subgroup within the autosomal recessive ichthyoses. Sjögren-Larsson syndrome (SLS) shows a deficiency of both acyl-ceramides (ceramides 1 and 6), which would seem likely to disrupt the normal skin barrier function. Furthermore, glucosylceramides (cerebrosides) are known to be deficient in the neural tissue of patients with SLS. The relationship of these ceramide abnormalities to the underlying fatty alcohol oxidoreductase defect remains uncertain, but they may provide an interesting link between the nerve damage and cutaneous abnormalities seen in this rare neurodermatosis.

What syndrome is this? Sjögren-Larsson syndrome

Sjögren-Larsson syndrome is an inborn error of metabolism with its primary clinical manifestations being congenital ichthyosis, spastic hemiplegia or quadriplegia, and moderate to severe mental retardation. Definitive diagnosis can be made by measuring fatty aldehyde dehydrogenase activity in cultured skin fibroblasts. Treatment of dermatologic manifestations is best accomplished with topical emollients and frequent bathing or showering. Some evidence supports medium-chain triglyceride diets and oral retinoids. These modalities, however, remain controversial.

Carrier detection for Sjögren-Larsson syndrome

Sjögren-Larsson syndrome (SLS) is an autosomal recessive disorder associated with reduced activity of the fatty alcohol: NAD+ oxidoreductase complex (FAO). Recent studies indicate that SLS patients are specifically deficient in the fatty aldehyde dehydrogenase (FALDH) component of FAO. To investigate the possibility of carrier detection for SLS, FAO and FALDH activities were measured in cultured skin fibroblasts from normal controls, obligate SLS heterozygotes, and SLS homozygotes using the 18-carbon substrates octadecanol and octadecanal. Three of 11 heterozygotes for SLS had FAO activities that were within the normal range; the other 8 SLS heterozygotes had FAO activities below normal. In contrast, fibroblast FALDH activity was more effective than FAO in discriminating SLS heterozygotes from normal controls. FALDH activity (nmol min-1 (mg protein)-1) in normal controls was 8.54 +/- 1.16 (mean +/- SD; range 6.95-10.77; n = 12) and in SLS heterozygotes was 5.12 +/- 1.31 (range 3.28-6.96; n = 11), or 60 +/- 15% of mean normal activity. One SLS heterozygote had an FALDH activity within the lower range of normal; this heterozygote had an FAO activity below normal. None of the SLS heterozygotes had an FAO or FALDH activity that was in the range of that measured in SLS homozygotes. These results indicate that measurement of FAO and FALDH activities in cultured skin fibroblasts using 18-carbon substrates is useful for SLS carrier detection.

Sjögren-Larsson syndrome. Deficient activity of the fatty aldehyde dehydrogenase component of fatty alcohol:NAD+ oxidoreductase in cultured fibroblasts

Sjögren-Larsson syndrome (SLS) is an inherited disorder associated with impaired fatty alcohol oxidation due to deficient activity of fatty alcohol:NAD+ oxidoreductase (FAO). FAO is a complex enzyme which consists of two separate proteins that sequentially catalyze the oxidation of fatty alcohol to fatty aldehyde and fatty acid. To determine which enzymatic component of FAO was deficient in SLS, we assayed fatty aldehyde dehydrogenase (FALDH) and fatty alcohol dehydrogenase in cultured fibroblasts from seven unrelated SLS patients. All SLS cells were selectively deficient in the FALDH component of FAO, and had normal activity of fatty alcohol dehydrogenase. The extent of FALDH deficiency in SLS cells depended on the aliphatic aldehyde used as substrate, ranging from 62% of mean normal activity using propionaldehyde as substrate to 8% of mean normal activity with octadecanal. FALDH activity in obligate SLS heterozygotes was partially decreased to 49 +/- 7% of mean normal activity using octadecanal as substrate. Differential centrifugation studies in fibroblasts indicated that this FALDH enzyme was largely particulate; soluble FALDH activity was normal in SLS cells. Intact SLS fibroblasts oxidized octadecanol to fatty acid at less than 10% of the normal rate, but oxidized free octadecanal normally, suggesting that the FALDH affected in SLS is chiefly involved in the oxidation of fatty alcohol to fatty acid. These results show that the primary enzymatic defect in SLS is the FALDH component of the FAO complex, which leads to deficient oxidation of fatty aldehyde derived from fatty alcohol.

Sjögren-Larsson syndrome: case reports

Sjögren-Larsson syndrome (SLS) is a rare, autosomal recessive disorder with worldwide distribution. It consists of ichthyosis, spastic diplegia, and mental retardation. An enzymatic defect in fatty alcohol oxidation recently was identified and is thought to be responsible for the disorder. We report two siblings with SLS. In addition to the typical features of the syndrome, the sister had marked hyperkeratosis of the palms and soles, which is rarely seen to this degree. The brother had joint hyperextensibility, which has not been reported previously. Both individuals had documented deficient activity of fatty alcohol:NAD+ oxidoreductase.

All about ichthyosis

From "alligator people" to "porcupine boys," the ichthyoses have been a distinctly recognizable entity for thousands of years. Recent improvements in biochemical and genetic research have allowed more scientific delineation of this class of diseases. This article covers the latest in pathophysiology, the major classes of ichthyoses, many of the newer minor ones, prenatal diagnosis, and treatment options.