Discriminative Features in Three Autosomal Recessive Cutis Laxa Syndromes: Cutis Laxa IIA, Cutis Laxa IIB, and Geroderma Osteoplastica

Identification of a novel intronic variant of ATP6V0A2 in a Han-Chinese family with cutis laxa

BACKGROUND

Cutis laxa is a connective tissue disease caused by abnormal synthesis or secretion of skin elastic fibers, leading to skin flabby and saggy in various body parts. It can be divided into congenital cutis laxa and acquired cutis laxa, and inherited cutis laxa syndromes is more common in clinic.

METHODS

In this study, we reported a case of a Han-Chinese male newborn with ATP6V0A2 gene variant leading to cutis laxa. The proband was identified by whole-exome sequencing to determine the novel variant, and their parents were verified by Sanger sequencing. Bioinformatics analysis and minigene assay were used to verify the effect of this variant on splicing function.

RESULTS

The main manifestations of the proband are skin laxity, abnormal facial features, and enlargement of the anterior fontanelle. Whole-exome sequencing showed that the newborn carried a non-canonical splicing-site variant c.117 + 5G > T, p. (?) in ATP6V0A2 gene. Sanger sequencing showed that both parents of the proband carried the heterozygous variant. The results of bioinformatics analysis and minigene assay displayed that the variant site affected the splicing function of pre-mRNA of the ATP6V0A2 gene.

CONCLUSIONS

In this study, it was identified that ATP6V0A2 gene c. 117 + 5G > T may be the cause of the disease. The non-canonical splicing variants of ATP6V0A2 gene were rarely reported in the past, and this variant expanded the variants spectrum of the gene. The functional study of minigene assay plays a certain role in improving the level of evidence for the pathogenicity of splicing variants, which lays a foundation for prenatal counseling and follow-up gene therapy.

Orthognathic Surgery with Interdisciplinary Digital Planning in Patients with Geroderma Osteodysplasticum: A Case Report

Patients with geroderma osteodysplasticum (GO) often times have dentofacial deformities and benefit from orthognathic surgery. Because of generalized osteopenia, operations must be prepared even more meticulously than usual, and the higher risk of unfortunate fractures (bad splits) should be explained to the patients in detail. This case report is intended to portray a digital, interdisciplinary and patient-individualized planning of orthognathic surgery. It points out the individual steps that must be considered and how they can be advantageously used in patients with underlying diseases or syndromes such as GO. Through a careful digital representation of the surgical options, production of the digitally modeled splints, 3D printing and good manual surgical implementation, the quality of life of patients with GO can be increased through orthognathic surgery. Both the functions in the oral, maxillofacial region and the patient's appearance in the case presented here benefited from the interdisciplinary, individualized and digital treatment approach.

Autosomal recessive cutis laxa type IIIA: Report of a patient with severe phenotype and review of the literature

Autosomal recessive cutis laxa type IIIA is a very rare genetic condition, caused by pathogenic variants in ALDH18A1, encoding delta-1-pyrroline-5-carboxylate synthase (P5CS). This enzyme catalyzes the reduction of glutamic acid to delta1-pyrroline-5-carboxylate, playing a key role in the de novo biosynthesis of proline, ornithine, and arginine. Autosomal recessive cutis laxa type IIIA is characterized by abundant and wrinkled skin, skeletal anomalies, cataract or corneal clouding and neuro-developmental disorders of variable degree. We report on a patient with autosomal recessive cutis laxa type IIIA, due to a homozygous missense c.1273C > T; p. (Arg425Cys) pathogenic variant in ALDH18A1. The patient presented a severe phenotype with serious urological involvement, peculiar cerebro-vascular abnormalities and neurodevelopmental compromise. This description contributes to better characterize the phenotypic spectrum associated with ALDH18A1 pathogenic variants, confirming the systemic involvement as a typical feature of autosomal recessive cutis laxa type IIIA.

Congenital Cutis Laxa: A Case Report and Literature Review

Cutis Laxa is a rare connective tissue disease featuring inelastic and saggy skin. It is thought that plastic surgery might be the most effective treatment, while the previous pieces of literature on the surgical treatment for Cutis Laxa complained of the recurrence. We report a patient of Congenital Cutis Laxa who has received systematic and sequential treatment based on plastic surgery. The patient is content with the effect of treatment, and there are no signs of recurrence after 5 months. By referring to relevant pieces of literature, we evaluate the clinical manifestations and diagnosis of the disease. A multi-step, systematic, and sequential treatment is recommended for the treatment of Congenital Cutis Laxa.

Structure, biochemistry, and gene expression patterns of the proline biosynthetic enzyme pyrroline-5-carboxylate reductase (PYCR), an emerging cancer therapy target

Proline metabolism features prominently in the unique metabolism of cancer cells. Proline biosynthetic genes are consistently upregulated in multiple cancers, while the proline catabolic enzyme proline dehydrogenase has dual, context-dependent pro-cancer and pro-apoptotic functions. Furthermore, the cycling of proline and Δ1-pyrroline-5-carboxylate through the proline cycle impacts cellular growth and death pathways by maintaining redox homeostasis between the cytosol and mitochondria. Here we focus on the last enzyme of proline biosynthesis, Δ1-pyrroline-5-carboxylate reductase, known as PYCR in humans. PYCR catalyzes the NAD(P)H-dependent reduction of Δ1-pyrroline-5-carboxylate to proline and forms the reductive half of the proline metabolic cycle. We review the research on the three-dimensional structure, biochemistry, inhibition, and cancer biology of PYCR. To provide a global view of PYCR gene upregulation in cancer, we mined RNA transcript databases to analyze differential gene expression in 28 cancer types. This analysis revealed strong, widespread upregulation of PYCR genes, especially PYCR1. Altogether, the research over the past 20 years makes a compelling case for PYCR as a cancer therapy target. We conclude with a discussion of some of the major challenges for the field, including developing isoform-specific inhibitors, elucidating the function of the long C-terminus of PYCR1/2, and characterizing the interactome of PYCR.

Clinical and Molecular Delineation of Cutis Laxa Syndromes: Paradigms for Homeostasis

Cutis laxa (CL) syndromes are a large and heterogeneous group of rare connective tissue disorders that share loose redundant skin as a hallmark clinical feature, which reflects dermal elastic fiber fragmentation. Both acquired and congenital-Mendelian- forms exist. Acquired forms are progressive and often preceded by inflammatory triggers in the skin, but may show systemic elastolysis. Mendelian forms are often pleiotropic in nature and classified upon systemic manifestations and mode of inheritance. Though impaired elastogenesis is a common denominator in all Mendelian forms of CL, the underlying gene defects are diverse and affect structural components of the elastic fiber or impair metabolic pathways interfering with cellular trafficking, proline synthesis, or mitochondrial functioning. In this chapter we provide a detailed overview of the clinical and molecular characteristics of the different cutis laxa types and review the latest insights on elastic fiber assembly and homeostasis from both human and animal studies.

The role of the Golgi apparatus in disease (Review)

The Golgi apparatus is known to underpin many important cellular homeostatic functions, including trafficking, sorting and modifications of proteins or lipids. These functions are dysregulated in neurodegenerative diseases, cancer, infectious diseases and cardiovascular diseases, and the number of disease-related genes associated with Golgi apparatus is on the increase. Recently, many studies have suggested that the mutations in the genes encoding Golgi resident proteins can trigger the occurrence of diseases. By summarizing the pathogenesis of these genetic diseases, it was found that most of these diseases have defects in membrane trafficking. Such defects typically result in mislocalization of proteins, impaired glycosylation of proteins, and the accumulation of undegraded proteins. In the present review, we aim to understand the patterns of mutations in the genes encoding Golgi resident proteins and decipher the interplay between Golgi resident proteins and membrane trafficking pathway in cells. Furthermore, the detection of Golgi resident protein in human serum samples has the potential to be used as a diagnostic tool for diseases, and its central role in membrane trafficking pathways provides possible targets for disease therapy. Thus, we also introduced the clinical value of Golgi apparatus in the present review.

Review of clinical and molecular variability in autosomal recessive cutis laxa 2A

ATP6V0A2-related cutis laxa, also known as autosomal recessive cutis laxa type 2A (ARCL2A), is a subtype of hereditary cutis laxa originally characterized by skin, skeletal, and neurological involvement, and a combined defect of N-glycosylation and O-glycosylation. The associated clinical spectrum subsequently expanded to a less severe phenotype dominated by cutaneous involvement. At the moment, ARCL2A was described in a few case reports and series only. An Italian adult woman ARCL2A with a phenotype restricted to skin and the two novel c.3G>C and c.1101dup ATP6V0A2 variants has been reported. A systematic literature review allowed us to identify 69 additional individuals from 64 families. Available data were scrutinized in order to describe the clinical and molecular variability of ARCL2A. About 78.3% of known variants were predicted null alleles, while 11 were missense and 2 affected noncanonical splice sites. Age at ascertainment appeared as the unique phenotypic discriminator with earlier age more commonly associated with facial dysmorphism (p .02), high/cleft palate (p .005), intellectual disability/global developmental delay (p .013), and seizures (p .024). No specific genotype-phenotype correlations were identified. This work confirmed the existence of an attenuated phenotype associated with ATP6V0A2 biallelic variants and offers an updated critique to the clinical and molecular variability of ARCL2A.

Premature aging disorders: A clinical and genetic compendium

Progeroid disorders make up a heterogeneous group of very rare hereditary diseases characterized by clinical signs that often mimic physiological aging in a premature manner. Apart from Hutchinson-Gilford progeria syndrome, one of the best-investigated progeroid disorders, a wide spectrum of other premature aging phenotypes exist, which differ significantly in their clinical presentation and molecular pathogenesis. Next-generation sequencing (NGS)-based approaches have made it feasible to determine the molecular diagnosis in the early stages of a disease. Nevertheless, a broad clinical knowledge on these disorders and their associated symptoms is still fundamental for a comprehensive patient management and for the interpretation of variants of unknown significance from NGS data sets. This review provides a detailed overview on characteristic clinical features and underlying molecular genetics of well-known as well as only recently identified premature aging disorders and also highlights novel findings towards future therapeutic options.

Homozygous deletion of MYADML2 in cranial asymmetry, reduced bone maturation, multiple dislocations, lumbar lordosis, and prominent clavicles

A null mutation in a patient can facilitate phenotype assignment and uncovers the function of that specific gene. We present five sibs of a consanguineous Pakistani family afflicted with a new syndrome with an unusual combination of skeletal anomalies including cranial asymmetry, fused sagittal sutures deviating from the medial axis, mandibular prognathia, maxillary hypoplasia, misaligned and crowded teeth, delayed bone age, multiple dislocations, hypoplastic and malpositioned patellae, humeral intracondylar fissures, scapular dyskinesis, long limbs, lumbar lordosis, protruding chest, prominent clavicles, short 5th digital rays, and ventral transverse digital creases plus features of cutis laxa. We mapped the disease gene locus to a 3.62-Mb region at 17q25.3 and identified a homozygous deletion of maximal 7.3 kb deduced to totally inactivate MYADML2 and downstream gene PYCR1, biallelic variants in which cause autosomal recessive cutis laxa (ARCL). All five affected sibs had the most common features of ARCL but not many of the less common ones. We attributed the anomalies not typical for ARCL to MYADML2 deficit, because no other genetic defect possibly a candidate to underlie the skeletal phenotype was found. MYADML2 is a gene of unknown function, has not been studied, and has not been associated with disease. Our findings present a possible phenotype for MYADML2 deficit that includes impaired bone patterning and maturation, definitely show that the gene is not essential for survival, and provide a start point for future studies on the function of MYADML2 protein. Detection of new patients is needed to confirm and delineate MYADML2-deficiency phenotype.

Inborn errors of metabolism leading to neuronal migration defects

The development and organisation of the human brain start in the embryonic stage and is a highly complex orchestrated process. It depends on series of cellular mechanisms that are precisely regulated by multiple proteins, signalling pathways and non-protein-coding genes. A crucial process during cerebral cortex development is the migration of nascent neuronal cells to their appropriate positions and their associated differentiation into layer-specific neurons. Neuronal migration defects (NMD) comprise a heterogeneous group of neurodevelopmental disorders including monogenetic disorders and residual syndromes due to damaging factors during prenatal development like infections, maternal diabetes mellitus or phenylketonuria, trauma, and drug use. Multifactorial causes are also possible. Classification into lissencephaly, polymicrogyria, schizencephaly, and neuronal heterotopia is based on the visible morphologic cortex anomalies. Characteristic clinical features of NMDs are severe psychomotor developmental delay, severe intellectual disability, intractable epilepsy, and dysmorphisms. Neurometabolic disorders only form a small subgroup within the large group of NMDs. The prototypes are peroxisomal biogenesis disorders, peroxisomal ß-oxidation defects and congenital disorders of O-glycosylation. The rapid evolution of biotechnology has resulted in an ongoing identification of metabolic and non-metabolic disease genes for NMDs. Nevertheless, we are far away from understanding the specific role of cortical genes and metabolites on spatial and temporal regulation of human cortex development and associated malformations. This limited understanding of the pathogenesis hinders the attempt for therapeutic approaches. In this article, we provide an overview of the most important cortical malformations and potential underlying neurometabolic disorders.

ATP6V0A2-related cutis laxa in 10 novel patients: Focus on clinical variability and expansion of the phenotype

In ATP6V0A2-related cutis laxa, the skin phenotype varies from a wrinkly skin to prominent cutis laxa and typically associates with skeletal and neurological manifestations. The phenotype remains incompletely characterized, especially in adult patients. Glycosylation defects and reduced acidification of secretory vesicles contribute to the pathogenesis, but the consequences at the clinical level remain to be determined. Moreover, the morphology of the elastic fibres has not been studied in ATP6V0A2-related cutis laxa, nor its relation with potential clinical risks. We report on the extreme variability in ATP6V0A2-related cutis laxa in 10 novel patients, expand the phenotype with emphysema and von Willebrand disease and hypothesize on the pathogenesis that might link both with deficiency of glycosylation and with elastic fibre anomalies. Our data will affect clinical management of patients with ATP6V0A2-related cutis laxa.

Cutis laxa in a patient with 1p36 deletion syndrome

Chromosome 1p36 deletion is the most common subtelomeric deletion syndrome characterized by variable features including unique facial appearance, intellectual disability, developmental delay, cardiac defects, seizures and hypotonia. Here, we report a patient with developmental delay, dilated cardiomyopathy, seizures, hirsutism and cutis laxa who was diagnosed with 1p36 deletion syndrome by chromosome microarray analysis. This patient is the first reported case of 1p36 deletion syndrome associated with cutis laxa and our results suggest that the 1p36 region contains one or more genes relevant to cutis laxa. This case also indicates the importance of considering chromosome abnormalities (microdeletion/microduplication syndromes) in patients presenting skin disorders combined with unexplained developmental delay, intellectual disability or multiple congenital abnormalities.

Geroderma osteodysplasticum: Histological features and the role of panel-based exome sequencing in diagnosis

Geroderma osteodysplasticum (GO) has clinical and histological features that overlap with other causes of wrinkly skin. Here we present the case of a child diagnosed with GO following exome sequencing of a panel of genes covering the wide differential diagnosis. The histological features of the overlapping conditions are presented, highlighting the utility of panel testing for conditions of this type. This is relevant to many genetic conditions and can influence ongoing management as exemplified by this case.

Near-fatal presentation of bilateral pneumothorax in cutis laxa patient: Case report, and review of the literature

Cutis laxa (CL) is a rare connective tissue disease characterized by a loose, wrinkled, and inelastic skin. Here, we report an unusual presentation in a 15-year-old male patient who is a known patient of CL who presented with bilateral pneumothorax. He was successfully managed initially by chest tube insertion and then he was treated surgically with bilateral staged thoracoscopy, apical bullectomy, and pleurodesis with full uneventful recovery.