Zellweger syndrome caused by PEX6 gene variation in 2 cases and literature review / 中华儿科杂志

Objective: To summarize the clinical features and genetic characteristics of Zellweger spectrum disorder caused by PEX6 gene variation. Methods: This was a case series research. Clinical date and genetic results of 2 neonatal cases of Zellweger syndrome caused by PEX6 gene variation in Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology and Affiliated Hospital of Guangdong Medical University from July 2021 to July 2022 were retrospectively collected and analyzed. Literature up to August 2023 was searched from electronic databases of China National Knowledge Infrastructure (CNKI), Wanfang Data and PubMed with the combined keywords of "Zellweger syndrome" "Zellweger spectrum disorder", and "PEX6 gene" both in Chinese and English. The main clinical features and genetic characteristics of Zellweger spectrum disorder caused by PEX6 gene variation were summarized. Results: The 2 male neonates both developed clinical manifestations as dyspnea, hypotonia, feeding difficulties, enlarged fontanelle, and high palatine arch after birth. Biochemical parameters indicated elevated bile acids, and the cranial ultrasound showed the enlarged bilateral ventricles and subependymal cyst in both 2 neonates. Zellweger syndrome was confirmed by whole exome sequencing, and the results revealed PEX6 gene variation in the 2 neonates, including compound heterozygous variants c.315G>A and c.2095-3T>G, and homozygous variant c.506_507del. Case 1 was hospitalized for 5 days, and case 2 for 32 days; they both died shortly after being discharged (the specific time is unknown). Literature review found 26 patients, including 2 neonates in this study, with Zellweger spectrum disorder caused by PEX6 gene defect reported in 1 Chinese article and 11 English articles. Clinical features included hearing loss (19 cases), developmental delay (19 cases), vision impairment (19 cases), elevated very long chain fatty acids (17 cases), brain malformations (15 cases), hypotonia (12 cases), hepatic insufficiency (12 cases), distinctive facies (10 cases), and dental impairment (9 cases). Compound heterozygous variations dominated the variation types (15 cases), and the frameshift variations (16 cases) were the main pathogenic variations. Conclusions: Zellweger spectrum disorder should be considered when neonates show hypotonia, feeding difficulty, distinctive facial appearance, brain malformations and failure of hearing screening, or when older children show retinitis pigmentosa, sensorineural hearing loss, amelogenesis imperfecta and developmental delays. Detection of genetic variation in the PEX gene is crucial for definitive diagnosis.

Trastornos de migración neuronal / Neuronal migration Disorders

Los trastornos de migración neuronal representan un grupo de malformaciones congénitas del sistema nervioso, que alteran el proceso en el que millones de células migran de la matríz germinal, hacia el sitio en el que residirán el resto de la vida. De manera particular, en la corteza cerebral provocan cambios importantes en la citoarquitectura, laminación y fisiología neuronal normal. Aparecen como casos esporádicos, determinados genéticamente o causados por agentes externos como infecciones, intoxicaciones, radiaciones, etc. Las entidades nosológicas mejor identificadas incluyen: esquizencefalia, licencefalia, paquigiria, polimicrogiria, heterotopias neuronales y agensia del cuerpo calloso. Los portadores del padecimiento habitualmente presentan síntomas y signos tempranos de la enfermedad, siendo la epilepsia una manifestación clínica dominante. Mediante estudios de tomografía craneal computada (TCC), resonancia magnética (RM), tomografía por emisión de fotón simple (TCEFS) y estudios de inmuno-histoquímica con técnica de Golgi (IHG), recientemente se ha demostrado que estas disgenesias pueden ser una causa frecuente de muchas epilepsias y síndromes epilépticos refractarios a tratamiento médico, considerados previamente como criptogénicos. Cuando se asocian a estos padecimientos estigmas dismórficos, pueden constituir síndromes genéticos como el de Miller-Dieker, Zellweger y Aicardi

Síndrome cerebrohepatorrenal de Zellweger: una enfermedad peroxisomal / Brain-liver-renal Zellweger syndrome: a peroxisomal disease

Se describe el caso clínico de un lactante con dismorfias craneofacilaes, hepatomegalia, quistes renales y disfunción neurológica severa. Los exámenes de rastreo para aminoacidemia, aminoaciduria, ácido láctico y amonio dieron resultados normales, pero había altas concentraciones plasmáticas de ácidos grasos de cadena muy larga, distribución subcelular anormal de la catalasa peroxisomal y fantasmas peroxisomales en fibroblastos cultivados. Estas características clínicas y de laboratorio sustentan el diagnóstico de síndrome de Zellweger

Zellweger syndrome: first reported case in Thailand and literature review.

We describe an infant boy with facial dysmorphism, profound hypotonia, psychomotor retardation, seizure and hepatomegaly. Biochemical study revealed elevation of very long chain fatty acids and pipecolic acid, consistent with peroxisomal disorder. He died at the age of 4 months. Electron microscopic study demonstrated decreased amounts of peroxisomes in liver and kidneys. The clinical characteristic, accompanied the biochemical and microscopic findings led to the diagnosis of Zellweger syndrome. The recognition of this syndrome is important since it is a fatal disease. The pattern of inheritance is autosomal recessive, hence genetic counseling is necessary. We emphasize that peroxisomal disorder should be included in the differential diagnosis in patients with infantile hypotonia. This patient is the first reported case of Zellweger syndrome in Thailand.

Zellweger (cerebro-hepato-renal) syndrome: first brazilian case with confirmed peroxisomal defect

A síndrome de Zellweger (ZS) é uma doença recessiva causada por uma deficiência generalizada das funçöes peroxissônicas, sendo um exemplo ilustrativo de uma doença metabólica herdada que usualmente chama a atençäo já no período neonatal pelo seu quadro dismórfico típico. Embora a suspeita de ZS seja freqüentemente levantada nas unidades neonatais, o diagnóstico é raramente confirmado uma vez que ele exige procedimentos bioquímicos sofisticados. Neste artigo é descrito um paciente com ZS que, tanto quanto estejamos informados, é o primeiro caso brasileiro no qual o defeito peroxissômico foi confirmado bioquimicamente. Os autores ressaltam a importância da confirmaçäo bioquímica do diagnóstico de ZS, uma vez que ela permite näo apenas um melhor delineamento do fenótipo da síndrome mas principalmente porque permite a prevençäo de casos adicionais através do aconselhamento genético e do diagnóstico pré-natal