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A mosaic is an organism composed of two or more genetically distinct cell populations
derived from a genetically homogeneous zygote. Cutaneous mosaicisms are the clinical
expressions of these disorders. The main event which allows the existence of
mosaicism is a genetic mutation, either structural or functional. Cutaneous
mosaicisms usually manifes...
Citations
... 20 The mosaicism pattern, according to the distribution of vascular and pigmentary lesions, was classified as Blaschko lines, checkboard, phylloid, patchy pattern without midline separation and lateralization. 21 Skin biopsies, from either vascular lesion or pigmentary lesion or both when possible, and peripheral blood samples were collected from all participants. ...
Importance
Postzygotic mutations in the GNAQ/GNA11 genes, which encode the G‐protein nucleotide binding protein alpha subunits, have been identified in patients with phakomatosis pigmentovascularis (PPV). However, little is known about the Chinese population.
Objective
To identify pathogenic mutations in pediatric patients with PPV within the Chinese population.
Methods
We performed whole‐exome sequencing (WES) using skin lesion tissues from pediatric patients diagnosed with PPV. Additionally, ultradeep‐targeted sequencing was conducted to validate the somatic mutations. A genotype‐phenotype correlation was analyzed by integrating data from previous reports with the findings of the present study.
Results
Thirteen patients were enrolled, all diagnosed with the cesioflammea type of PPV, except for one patient with an unclassifiable type. We identified somatic GNA11 c.547C>T (p.R183C) variant in seven patients and GNAQ c.548G>A (p.R183Q) in four patients, with low allelic fractions ranging from 2.1% to 8.6% through ultradeep sequencing. Besides, a GNAQ c.548G>A (p.R183Q) variant was detected through targeted sequencing in one of two patients who did not exhibit detectable variants via WES. The genotype‐phenotype correlation analysis, involving 15 patients with a GNA11 variant and 10 with a GNAQ variant, revealed that facial capillary malformation (87% vs. 50%, P = 0.075) and ocular melanocytosis (80% vs. 40%, P = 0.087) appeared to be more frequent in patients with GNA11 mutation compared to those with GNAQ mutations. All four patients diagnosed with cesiomarmorata type or overlapping cesioflammea and cesiomarmorata type PPV carried the GNA11 variant.
Interpretation
Our study demonstrated that the majority of PPV patients in the Chinese population carried a postzygotic variant of GNAQ/GNA11, thus further confirming the pathogenic role of GNAQ/GNA11 mosaicism in the development of PPV cesioflammea type.
... A fantastical monster originally denoted by the term "chimera," but in contemporary medicine the term refers to a biological being made up ISSN: 2583-4053 Volume-2 Issue-2 || April 2023 || PP. 259-267 https://doi.org/10.55544/jrasb. 2 ...
... To complicate matters, clinicians have historically used the word "mosaic" to describe twotoned skin patterns that sometimes occur in natural chimeras (Kouzak et al., 2013) Within the field of dermatology, the term "mosaic" denotes a perceived pattern or arrangement present on the surface of the skin. The design exhibits similarities to artistic mosaics. ...
... Male fetal progenitor cells persist in maternal blood for as long as 27 years postpartum. Proceedings of the National Academy of Sciences, 93 (2), 705-708. ...
Chimera has several important definitions that are common to each other, where he is known a single creature that is made up of two or more separate populations of genetically unique cells that originated from various zygotes. Definition can be interpreted as cells from one person might appear in another individual in a process known as chimerism. These cells may be incorporated into the parenchyma or they may circulate. Chimeras are divided into several types depending on several factors such as the percentage of chimera cells in the body of the organism neighborhood, origin, or other reasons, which includes microchimeras, natural human macro-chimeras and man-made chimeras. Chimeric cells in human can arise from three significant sources, namely originating from gestation, blood transfusions, and transplants.
... When a somatic mutation or chromosomal nondisjunction occurs during embryogenesis, affecting an epidermal progenitor cell, the affected offspring cells proliferate and migrate along the lines of Blaschko. 4 Currently, there is no standard treatment for BFH. Correct identification prevents patients from undergoing CASE LETTER unnecessary surgery and also allows periodic monitoring to detect malignant transformations. ...
... Although local recurrences are common, the rate of CIF metastasis is less than 10% and the ten-year survival rate is up to 90%. 3 The extremities are more commonly affected and lesions located on the trunk, head and neck are less frequent, although they are more aggressive. 1,4 Due to the risk of local recurrence, extensive surgical resection is recommended. Surgery alone shows recurrence rates of 17% to 40%. ...
... Immunohistochemistry is positive for vimentin and, in some cases, for desmin, smooth muscle actin, and cytokeratin. 4 CIF is characterized in up to 85% of cases by a specific t(12;15) (p13:q25) chromosomal translocation encoding an ETV6-NTRK3 gene fusion. 1,3---5 The diagnosis of CIF should always be considered in the presence of a congenital, spherical, bleeding extremity tumor in children, aiming to avoid treatment delays. ...
... Pigmentary mosaicism, or hypomelanosis of Ito (HI, MIM# 300337), is a rare neurocutaneous syndrome characterized by hypopigmented skin whorls along Blaschko's lines. It is associated with nervous system abnormality and other ectodermal defects involving fingers, toes, and teeth (Kouzak et al. 2013;Sybert 1994). Hypopigmented lesions have a reduced number of melanocytes, which originate from neural crest cells (Carmignac et al. 2021;Kuster and Konig 1999;Lee et al. 1999). ...
Pigmentary mosaicism of the Ito type, also known as hypomelanosis of Ito, is a neurocutaneous syndrome considered to be predominantly caused by somatic chromosomal mosaicism. However, a few monogenic causes of pigmentary mosaicism have been recently reported. Eleven unrelated individuals with pigmentary mosaicism (mostly hypopigmented skin) were recruited for this study. Skin punch biopsies of the probands and trio-based blood samples (from probands and both biological parents) were collected, and genomic DNA was extracted and analyzed by exome sequencing. In all patients, plausible monogenic causes were detected with somatic and germline variants identified in five and six patients, respectively. Among the somatic variants, four patients had MTOR variant (36%) and another had an RHOA variant. De novo germline variants in USP9X, TFE3, and KCNQ5 were detected in two, one, and one patients, respectively. A maternally inherited PHF6 variant was detected in one patient with hyperpigmented skin. Compound heterozygous GTF3C5 variants were highlighted as strong candidates in the remaining patient. Exome sequencing, using patients’ blood and skin samples is highly recommended as the first choice for detecting causative genetic variants of pigmentary mosaicism.
... This skin finding has an association with the presence of mosaicism. 19 Survival of mosaic trisomy 8 patients has been variable and seems to be influenced by the presence of some underlying major malformations. 8,17 In our patient, it is noteworthy that the presence of a moderate laryngotracheomalacia. ...
Mosaic trisomy 8 is a condition characterized by a great phenotypic and cytogenetic variability whose incidence ranges around 1 in 25,000 to 50,000 live births. Here, we report a mosaic trisomy 8 patient presenting laryngotracheomalacia, an uncommon finding, analyzing its possible role over morbidity, and mortality. The patient was a boy who, after birth, had tachypnea and paleness. He presented periods of respiratory dysfunction with need of ventilatory support. Respiratory syncytial virus test was positive. Naso fibrobronchoscopy showed moderate laryngotracheomalacia. He also had recurrent episodes of pneumonia and difficulty in withdrawing continuous positive airway pressure. The patient also presented leucoma, abnormal and low-set ears, pectus excavatum, clenched fists with overlapping fingers, cryptorchidism, clubfeet, and deep longitudinal plantar creases. G-bands by Trypsin using giemsa (GTG-banding) karyotype from a peripheral blood sample revealed a mosaic trisomy 8: mos 47,XY, + 8[15]/46,XY[7]. At 4 months, the patient developed respiratory failure, and a chest computed tomography scan showed areas of atelectasis and gross fibroatelectatic striae. He ended up presenting clinical worsening and died at 4 months and 8 days. In our literature review, we found some reports describing patients with mosaic trisomy 8 and laryngotracheomalacia. However, we cannot rule out the possibility that this association could be casual, since laryngotracheomalacia is a relatively common finding in children. Therefore, more studies are still necessary to understand the possible relation between both conditions and the role of laryngotracheomalacia over morbidity and prognosis of mosaic trisomy 8 patients.
... Lesions were differentiated from lichen plano pilaris and follicular lichen planus on basis of dermatoscopic patterns (pigment dots and globules, vitiligo, pemphigus vulgaris, granuloma annulare, dermatomyositis and systemic lupus erythematosus. 3 Lines of blaschko are postulated to correspond to the migration of ectodermal and neuroectodermal cells during embryogenesis and also thought to reflect T-lymphocytic migration and clonal expression during embryogenesis of skin. 4 A loss of heterozygosity of one of the concerned genes distributed along lines of Blaschko leads to superimposed segmental manifestation. 3 Linear lesions are usually seen in lichen planus; however, there are only a few reports of blaschkoid lichen planus pigmentosus. 5,6 We were unable to find a previous similar report of blaschkoid follicular lichen planus pigmentosus in literature. ...
... Lesions were differentiated from lichen plano pilaris and follicular lichen planus on basis of dermatoscopic patterns (pigment dots and globules, vitiligo, pemphigus vulgaris, granuloma annulare, dermatomyositis and systemic lupus erythematosus. 3 Lines of blaschko are postulated to correspond to the migration of ectodermal and neuroectodermal cells during embryogenesis and also thought to reflect T-lymphocytic migration and clonal expression during embryogenesis of skin. 4 A loss of heterozygosity of one of the concerned genes distributed along lines of Blaschko leads to superimposed segmental manifestation. 3 Linear lesions are usually seen in lichen planus; however, there are only a few reports of blaschkoid lichen planus pigmentosus. 5,6 We were unable to find a previous similar report of blaschkoid follicular lichen planus pigmentosus in literature. ...
Introduction:
Some therapeutic decisions in vitiligo depend on the likelihood of the disease remaining stable and inactive.
Aim:
To determine a period of disease stability in vitiligo following which reactivation was unlikely.
Materials and methods:
This cross-sectional descriptive study was carried out in 200 patients where a detailed clinical history of the disease activity and stability over the course of vitiligo was recorded.
Results:
There were 167 (83.5%) patients with non-segmental vitiligo and 33 (16.5%) with segmental vitiligo. For every 1-year increase in the duration of the disease, stable and active periods increased by 0.7 and 0.3 years, respectively in non-segmental vitiligo and by 0.9 and 0.1 years in segmental vitiligo (P < 0.01). When segmental vitiligo was stable for at least 2 years, it was five times less likely to re-activate than the disease that was stable for less than 2 years (P = 0.16). However, in non-segmental vitiligo, we found no association between the duration of stability and risk of reactivation.
Conclusions:
Segmental vitiligo usually becomes inactive after the disease has been stable for 2 years. Non-segmental vitiligo is prone to reactivation even after prolonged periods of stability.
... Nevertheless, Blaschko's lines or bands which are considered as ectodermal developmental segments of skin (or embryonal pigmentary segments as Dr. Sarma refers to) cannot be missed in such lesions. 6 We had clearly stated that linear, curvilinear and circular bands around appendages and orifices on the face were consistent with Blaschko's patterns. We also demonstrated segmental involvement of vitiligo in different combinations and permutations within the anatomic segments of the body as well. ...
... They are characterized by inflammatory infiltrate and distribution along the lines of Blaschko. The most common of these are lichen striatus and blaschkitis, which are distinguished by age of onset, location, and histopathological features [1][2][3]. ...
... These can be linear or correspond to patterns such as Blaschko's lines, dermatomes, Langer's lines, or Voigt's lines, each of which has physiological etiologies. Blaschko's lines were first described by Alfred Blaschko in 1901 and are thought to reflect patterns of cell migration and clonal expansion during the embryonic development of the epidermis [2]. ...
... It depends on their location. They appear in a V-shaped configuration on the back, in an S-shaped configuration on the anterior abdomen, and linearly on the extremities [2]. ...
Cutaneous conditions can follow Blaschko's lines on the skin, which are thought to reflect patterns of cell migration and clonal expansion during embryonic development of the epidermis. These diseases are hypothesized to be caused by genetic mosaicism resulting from processes such as lyonization or somatic postzygotic mutation. Lichen striatus and blaschkitis are two such acquired inflammatory skin disorders that are distinguished in the literature by age of onset, location, and histopathological features. Lichen striatus is typically observed on the extremities of children and is characterized by lichenoid papules that appear in a linear distribution along Blaschko's lines. Microscopic examination typically shows spongiosis, as well as lichenoid and periadnexal inflammation. Blaschkitis more commonly occurs in adults and frequently involves the truncal areas, including the chest and abdomen. Microscopic examination typically shows spongiotic dermatitis. We describe a young man with a linear eruption extending from the flexor aspect of his right wrist to his central chest, which has features of both lichen striatus and blaschkitis. Both lichen striatus and blaschkitis are self-limited diseases that may resolve within months. It has been suggested that lichen striatus and blaschkitis are not separate entities, but rather the two endpoints within the spectrum of blaschkolinear acquired inflammatory skin eruption (BLAISE). The overlapping features of lichen striatus and blaschkitis in our patient demonstrate the spectrum of clinical and pathologic features in patients with BLAISE.
... These lines illustrate ectodermal development patterns. This distribution pattern, especially on the trunk, is frequently hard to distinguish from dermatomes [12]. ...
... Since then, multiple reviews have been published 9,18,[23][24][25][26] , and many authors, including some of us, have proposed mosaicism classifications, focusing on the pattern of affected regions of the body and the type of underlying mechanism 25 . As well, there have been many attempts to classify genetic mosaicism of the skin 25,27 . Happle 3,28 emphasized the overlapping nature of proposed categories. ...
Mosaicism denotes an individual who has at least two populations of cells with distinct genotypes that are derived from a single fertilized egg. Genetic variation among the cell lines can involve whole chromosomes, structural or copy-number variants, small or single-nucleotide variants, or epigenetic variants. The mutational events that underlie mosaic variants occur during mitotic cell divisions after fertilization and zygote formation. The initiating mutational event can occur in any types of cell at any time in development, leading to enormous variation in the distribution and phenotypic effect of mosaicism. A number of classification proposals have been put forward to classify genetic mosaicism into categories based on the location, pattern, and mechanisms of the disease. We here propose a new classification of genetic mosaicism that considers the affected tissue, the pattern and distribution of the mosaicism, the pathogenicity of the variant, the direction of the change (benign to pathogenic vs. pathogenic to benign), and the postzygotic mutational mechanism. The accurate and comprehensive categorization and subtyping of mosaicisms is important and has potential clinical utility to define the natural history of these disorders, tailor follow-up frequency and interventions, estimate recurrence risks, and guide therapeutic decisions.
