Atypical Rett syndrome in a girl with mosaic triple X and MECP2 variant

Goltz Syndrome Combined with Triple X Syndrome, a Case Report

Goltz syndrome is a rare X-linked dominant multisystem disorder that presents with ectoderm and mesoderm-derived symptoms. Skin manifestations including congenital patchy skin aplasia, congenital nodular fat herniation, congenital hypo- or hyperpigmentation along Blaschko's lines, telangiectasia, and congenital ridged dysplastic nails are typical in this disorder. Almost all cases of Goltz syndrome correspond to female newborns and that hemizygosis makes the syndrome fetal in males. Triple X syndrome is a relatively common congenital disorder that presents with mild to no symptoms in the developmental and psychiatric realm. The patient reported here was born with multisystem anomaly affecting the eyes, craniofacial region, cardiovascular system, skin, and limbs. A G-banding chromosomal study revealed 47, XXX. She was diagnosed with Goltz syndrome owing to her distinctive skin manifestations. The congenital cervical skin defect healed with conservative treatment. The facial cleft, cleft lip-palate, and syndactyly were successfully treated with multiple surgical treatments. The combination of triple X syndrome and Goltz syndrome is very rare. We describe the expression of presenting with both syndromes simultaneously.

Sleep Disorders in Rett Syndrome and Rett-Related Disorders: A Narrative Review

Rett Syndrome (RTT) is a rare and severe X-linked developmental brain disorder that occurs primarily in females, with a ratio of 1:10.000. De novo mutations in the Methyl-CpG Binding protein 2 (MECP2) gene on the long arm of X chromosome are responsible for more than 95% cases of classical Rett. In the remaining cases (atypical Rett), other genes are involved such as the cyclin-dependent kinase-like 5 (CDKL5) and the forkhead box G1 (FOXG1). Duplications of the MECP2 locus cause MECP2 duplication syndrome (MDS) which concerns about 1% of male patients with intellectual disability. Sleep disorders are common in individuals with intellectual disability, while the prevalence in children is between 16 and 42%. Over 80% of individuals affected by RTT show sleep problems, with a higher prevalence in the first 7 years of life and some degree of variability in correlation to age and genotype. Abnormalities in circadian rhythm and loss of glutamate homeostasis play a key role in the development of these disorders. Sleep disorders, epilepsy, gastrointestinal problems characterize CDKL5 Deficiency Disorder (CDD). Sleep impairment is an area of overlap between RTT and MECP2 duplication syndrome along with epilepsy, regression and others. Sleep dysfunction and epilepsy are deeply linked. Sleep deprivation could be an aggravating factor of epilepsy and anti-comitial therapy could interfere in sleep structure. Epilepsy prevalence in atypical Rett syndrome with severe clinical phenotype is higher than in classical Rett syndrome. However, RTT present a significant lifetime risk of epilepsy too. Sleep disturbances impact on child's development and patients' families and the evidence for its management is still limited. The aim of this review is to analyze pathophysiology, clinical features, the impact on other comorbidities and the management of sleep disorders in Rett syndrome and Rett-related syndrome.

The comorbidity landscape of 47,XXX syndrome: A nationwide epidemiologic study

PURPOSE

This study aimed to describe the comorbidity pattern in 47,XXX syndrome.

METHODS

This was a registry-based study of hospital diagnoses and prescribed medication in a nationwide cohort of females with 47,XXX (n = 103) and 46,XX/47,XXX (n = 57) in which they were compared with 16,000 age-matched general population female controls.

RESULTS

The overall occurrence of hospital diagnoses was significantly increased in females with 47,XXX when compared with controls (incidence rate ratio = 2.1, CI = 1.7-2.5), and when divided into 19 organ-specific groups, there was a significantly increased risk in the following 14 groups: infection, blood, endocrine and metabolism, mental, nervous system, eye, ear, respiratory, oral cavity and gastrointestinal, musculoskeletal, perinatal, congenital malformations, external factors, and "other." The risk of being prescribed any medication was not significantly increased in females with 47,XXX when compared with controls (hazard ratio = 1.2, CI = 0.9-1.4). However, when stratified according to medication groups, a significantly increased risk was detected in 4 of 13 groups. The overall occurrence of hospital diagnoses was also significantly increased when females with 46,XX/47,XXX were compared with controls (incidence risk ratio = 1.3, CI = 1.01-1.8), but generally, in comparison with controls, females with 46,XX/47,XXX were less severely affected than females with 47,XXX.

CONCLUSION

The 47,XXX syndrome is associated with an increased occurrence of a wide variety of diseases. Increased awareness of this may contribute to improve counseling and clinical assessment of these patients.

Role of DNA Methyl-CpG-Binding Protein MeCP2 in Rett Syndrome Pathobiology and Mechanism of Disease

Rett Syndrome (RTT) is a severe, rare, and progressive developmental disorder with patients displaying neurological regression and autism spectrum features. The affected individuals are primarily young females, and more than 95% of patients carry de novo mutation(s) in the Methyl-CpG-Binding Protein 2 (MECP2) gene. While the majority of RTT patients have MECP2 mutations (classical RTT), a small fraction of the patients (atypical RTT) may carry genetic mutations in other genes such as the cyclin-dependent kinase-like 5 (CDKL5) and FOXG1. Due to the neurological basis of RTT symptoms, MeCP2 function was originally studied in nerve cells (neurons). However, later research highlighted its importance in other cell types of the brain including glia. In this regard, scientists benefitted from modeling the disease using many different cellular systems and transgenic mice with loss- or gain-of-function mutations. Additionally, limited research in human postmortem brain tissues provided invaluable findings in RTT pathobiology and disease mechanism. MeCP2 expression in the brain is tightly regulated, and its altered expression leads to abnormal brain function, implicating MeCP2 in some cases of autism spectrum disorders. In certain disease conditions, MeCP2 homeostasis control is impaired, the regulation of which in rodents involves a regulatory microRNA (miR132) and brain-derived neurotrophic factor (BDNF). Here, we will provide an overview of recent advances in understanding the underlying mechanism of disease in RTT and the associated genetic mutations in the MECP2 gene along with the pathobiology of the disease, the role of the two most studied protein variants (MeCP2E1 and MeCP2E2 isoforms), and the regulatory mechanisms that control MeCP2 homeostasis network in the brain, including BDNF and miR132.

Advances in understanding of Rett syndrome and MECP2 duplication syndrome: prospects for future therapies

The X-linked gene encoding MECP2 is involved in two severe and complex neurodevelopmental disorders. Loss of function of the MeCP2 protein underlies Rett syndrome, whereas duplications of the MECP2 locus cause MECP2 duplication syndrome. Research on the mechanisms by which MeCP2 exerts effects on gene expression in neurons, studies of animal models bearing different disease-causing mutations, and more in-depth observations of clinical presentations have clarified some issues even as they have raised further questions. Yet there is enough evidence so far to suggest possible approaches to therapy for these two diseases that could go beyond attempting to address specific signs and symptoms (of which there are many) and instead target the pathophysiology underlying MECP2 disorders. Further work could bring antisense oligonucleotides, deep brain stimulation, and gene therapy into the clinic within the next decade or so.

Atypical Rett syndrome in a girl with mosaic triple X and MECP2 variant

Background

Rett syndrome (RTT) is a neurodevelopmental disorder that predominantly affects girls, resulting from a loss‐of‐function variant in X‐linked MECP2. Here, we report a rare case of a girl with RTT with an X chromosome mosaic karyotype (46,XX/47,XXX).

Methods

Fluorescent in situ hybridization (FISH) was carried out to confirm the mosaic karyotype. Sanger sequencing was carried out to genetically diagnose RTT. Furthermore, we assessed the X chromosome inactivation (XCI) pattern. MECP2 expression levels were examined via RT‐PCR.

Results

The patient presented with preserved speech variant, the milder form of RTT. Genetic examination revealed a de novo, heterozygous, truncating variant of MECP2. FISH revealed mosaicism in the 47,XXX karyotype in 6% of her cells. The XCI assay revealed unbalanced inactivation with skewing in favor of the paternal X chromosome. MECP2 was downregulated to only 84% of the control, indicating that the patient's variant was probably of paternal origin. Unbalanced XCI in this patient might have contributed to the alleviation of the phenotype. However, her supernumerary X chromosome was derived from maternal X chromosome harboring the wild‐type allele and might have had no preferential effect on her RTT‐related phenotype.

Conclusion

The present results indicate that phenotypic effects of X chromosome aneuploidy depend on the nature of the supernumerary X chromosome, the pattern of mosaicism, and XCI status.