The Sjogren-Larsson syndrome (SLS) is a rare autosomal recessive disorder caused by pathogenic variants in the ALDH3A2 gene, which codes for fatty aldehyde dehydrogenase (FALDH). FALDH prevents the accumulation of toxic fatty aldehydes by converting them into fatty acids. Pathogenic ALDH3A2 variants cause symptoms such as ichthyosis, spasticity, intellectual disability, and a wide range of less common clinical features. Interpreting patient-to-patient variability is often complicated by inconsistent reporting and negatively impacts on establishing robust criteria to measure the success of SLS treatments. Thus, with this study, patient-centered literature data was merged into a concise genotype-based, open-access database (www.LOVD.nl/ALDH3A2). One hundred and seventy eight individuals with 90 unique SLS-causing variants were included with phenotypic data being available for more than 90%. While the three lead symptoms did occur in almost all cases, more heterogeneity was observed for other frequent clinical manifestations of SLS. However, a stringent genotype-phenotype correlation analysis was hampered by the considerable variability in reporting phenotypic features. Consequently, we compiled a set of recommendations of how to generate comprehensive SLS patient descriptions in the future. This will be of benefit on multiple levels, for example, in clinical diagnosis, basic research, and the development of novel treatment options for SLS.

Genotype and phenotype variability in Sjögren‐Larsson syndrome

Assessment of ten Egyptian patients with Sjogren-Larsson syndrome (SLS) detected; unusual clinical manifestations, a first report of brain atrophy in SLS, some patients exhibited neither retinal dots nor white matter changes previously reported as essential manifestations. We identified five mutations in ALDH3A2 gene including a novel one and suggest a founder effect. Sjogren-Larsson syndrome is a rare autosomal recessive inborn error of lipid metabolism caused by mutations in the ALDH3A2 gene that codes for fatty aldehyde dehydrogenase and result in a triad of ichthyosis, spasticity, and mental retardation. Clinical, radiological, biochemical, and neurophysiological evaluation in ten SLS patients descending from seven unrelated Egyptian pedigrees was followed by Sanger sequencing of ALDH3A2 performed by ABI 3500. All patients presented with SLS triad; ichthyosis, spasticity of four limbs and hyperreflexia with an intelligent quotient (IQ) ranging from (39 to 69). Other manifestations were dysmorphic features, seizures, and skeletal and ophthalmological affection. Mutational analysis of ALDH3A2 gene revealed three missense, one splice site, and one novel stop codon mutation; c.991G>T (p.E331X). Biochemical studies showed decrease of fatty aldehyde dehydrogenase activity. Our results reinforce the distinct clinical, radiological, and biochemical features of ALDH3A2-related SLS which are the clue for targeted molecular testing. Moreover, we present additional unreported clinical findings and a novel mutation thus expanding the phenotypic and mutational spectrum of this rare disorder.

Genetic assessment of ten Egyptian patients with Sjögren-Larsson syndrome: expanding the clinical spectrum and reporting a novel ALDH3A2 mutation.

Incontinentia pigmenti (IP) is an X-linked dominant genodermatosis. The disease is known to be caused by recurrent deletion of exons 4–10 of the Inhibitor Of Nuclear Factor Kappa B Kinase Regulatory Subunit Gamma (IKBKG) gene located at the Xq28 chromosomal region, which encodes for NEMO/IKKgamma, a regulatory protein involved in the nuclear factor kappa B (NF-κB) signaling pathway. NF-κB plays a prominent role in the modulation of cellular proliferation, apoptosis, and inflammation. IKBKG mutation that results in a loss-of-function or dysregulated NF-κB pathway contributes to the pathophysiology of IP. Aside from typical skin characteristics such as blistering rash and wart-like skin growth presented in IP patients, other clinical manifestations like central nervous system (CNS) and ocular anomalies have also been detected. To date, the clinical genotype-phenotype correlation remains unclear due to its highly variable phenotypic expressivity. Thus, genetic findings remain an essential tool in diagnosing IP, and understanding its genetic profile allows a greater possibility for personalized treatment. IP is slowly and gradually gaining attention in research, but there is much that remains to be understood. This review highlights the progress that has been made in IP including the different types of mutations detected in various populations, current diagnostic strategies, IKBKG pathophysiology, genotype-phenotype correlation, and treatment strategies, which provide insights into understanding this rare mendelian disorder.

Uncovering incontinentia pigmenti: From DNA sequence to pathophysiology

Incontinentia pigmenti (IP) is a rare X-linked skin disease caused by mutations in the IKBKG gene, which is required for activation of the nuclear factor-kappa B signalling pathway. Multiple systems can be affected with highly variable phenotypic expressivity. We aimed to clarify the clinical characteristics observed in molecularly confirmed Korean IP patients. The medical records of 25 females confirmed as IP by molecular genetic analysis were retrospectively reviewed. The phenotypic score of extracutaneous manifestations was calculated to assess the disease severity. The IKBKG gene partial deletion or intragenic mutations were investigated using long-range PCR, multiplex ligation-dependent probe amplification and direct sequencing methods. Among the 25 individuals, 18 (72%) were sporadic cases. All patients showed typical skin manifestations at birth or during the neonatal period. Extracutaneous findings were noted in 17 (68%) patients; ocular manifestations (28%), neurological abnormalities (28%), hair abnormalities (20%), dental anomalies (12%), nail dystrophy (8%). The common exon 4-10 IKBKG deletion was observed in 20 (80%) patients. In addition, five intragenic sequence variants were identified, including three novel variants. The phenotype scores were highly variable, ranging from abnormal skin pigmentation only to one or more extracutaneous features, although no significant difference was observed for each clinical characteristic between the group with sequence variants and that with common large deletion. Our cohort with IP showed heterogeneity of extracutaneous manifestations and high incidence of sporadic cases. Long-term monitoring with multidisciplinary management is essential for evaluating the clinical status, providing adequate genetic counselling and understanding the genotype-phenotype correlation in IP.

Importance of extracutaneous organ involvement in determining the clinical severity and prognosis of incontinentia pigmenti caused by mutations in the IKBKG gene

Incontinentia pigmenti (IP) is an uncommon neurocutaneous syndrome. Its initial diagnosis is based primarily on characteristic papulovesicular skin lesions and early-onset neonatal seizures. In contrast to typical early neurologic manifestations, we encountered a normally developed 6-month-old female patient with hyperpigmented whorls on her body. Following respiratory syncytial virus infection and fever, the patient exhibited status epilepticus. Brain magnetic resonance imaging studies of the patient were compatible with the findings of acute encephalopathy in IP. Genetic analysis showed an 11.7 kb deletion within the gene encoding inhibitor of kappa-B kinase gamma. The patient was treated with anticonvulsants and subsequently reached expected developmental milestones after discharge. These findings indicate that when a patient presents with status epilepticus, meticulous examination for skin lesions should be performed to determine whether the patient has a neurocutaneous syndrome, such as IP.

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A 6-Month-Old Girl with Incontinentia Pigmenti Presenting as Status Epilepticus.

Je Yeon Kim, M.D., Shin-Hye Kim, M.D., Mi-Jung Park, M.D., Soung Hee Kim, M.D., Woo Ho Cho, M.D., Jin Choi, M.D., Chang-Seok Ki, M.D., and Su Jeong You, M.D. Department of Pediatrics, Inje University Sanggye Paik Hospital, Inje University College of Medicine, Seoul; Department of Radiology, Inje University Sanggye Paik Hospital, Inje University College of Medicine, Seoul; Department of Ophthalmology, Inje University Sanggye Paik Hospital, Inje University College of Medicine, Seoul; Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea

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Su Jeong You

Papers

A 6-Month-Old Girl with Incontinentia Pigmenti Presenting as Status Epilepticus.

Identification of Homozygous Likely Pathogenic Variant of ALDH3A2 in a Korean Boy with Sjögren-Larsson Syndrome