Monozygotic Twin Sisters Research Articles

Can endogenous ethylene glycol production occur in humans? A detailed investigation of adult monozygotic twin sisters

Introduction To the best of our knowledge, clinically significant endogenous ethylene glycol production has never been reported in humans, very seldom reported in other animals or microorganisms, and then only under rare and specific conditions. We describe the detailed investigations we undertook in two adult monozygotic twin sisters to ascertain whether they were producing endogenous ethylene glycol. Methods Two previously healthy monozygotic adult twin sisters presented with recurrent episodes of apparent ethylene glycol poisoning beginning at age 35, requiring chronic hemodialysis to remove ethylene glycol and its metabolites as well as to restore metabolic homeostasis. The sisters denied ingestion or exposure to ethylene glycol. At their request, they were admitted to hospital under strict supervision to exclude surreptitious ingestion of ethylene glycol and to evaluate the need for treatment. Hemodialysis was withheld during this prospective study. Twin A was admitted for 14 days and twin B for 11 days. Serial biochemical analyses were performed in blood and urine. Clinical exome sequencing and mitochondrial deoxyribonucleic acid sequencing were also completed. Results In both twins, ethylene glycol was detected in urine, along with intermittent increases in concentrations of lactate, glycolate, and glycine in blood and/or urine. Blood ethylene glycol concentrations, however, remained <62 mg/L (<1 mmol/L) but became positive soon after discharge. The oxalate concentration remained normal in blood and urine. Plasma and urine amino acid profiles showed intermittent small increases in glycine, serine, taurine, proline, and/or alanine concentrations. Exome sequencing and mitochondrial deoxyribonucleic acid sequencing were non-diagnostic. Neither twin has been admitted with metabolic acidosis nor ethylene glycol poisoning since chronic hemodialysis was started. Twin A developed a calcium oxalate dihydrate lithiasis. Discussion Mitochondrial disease, methylmalonic/propionic/isovaleric aciduria, primary hyperoxaluria, and analyte error were all excluded in these twins, as were obvious common environmental exposures. Conclusion Detailed investigations were performed in adult monozygotic twin sisters to ascertain whether they were producing endogenous ethylene glycol. Alternative explanations were excluded to the very best of our efforts and knowledge. Global metabolomics, gut microbiome analyses, and whole genome sequencing are pending.

Fabry disease in female monozygotic twins with complex intronic haplotype variants: a case report

BackgroundFabry disease is an X-linked lysosomal storage disease caused by the impairment of α-galactosidase A. The complex intronic haplotype (CIH) variants, located in promoter and intronic regulatory lesions, has been found in patients with classical forms of Fabry disease. We present a case of Fabry disease in female monozygotic twins exhibiting the CIH mutation and classical manifestations.Case presentationA 61-year-old woman with a history of stroke, carotid artery occlusion, hypertrophic cardiomyopathy, and chronic kidney disease was referred to the nephrology clinic for management of her chronic kidney disease. Her monozygotic twin sister also presented with hypertrophic cardiomyopathy, atrial flutter, carotid stenosis, and proteinuria. Clinical symptoms and a comprehensive family history strongly suggested the presence of Fabry disease. Genetic analysis revealed the presence of 5 variants within a complex intronic haplotype (CIH): c.−10 C > T, c.369 + 990 C > A, c.370 − 81_370–77delCAGCC, c.640–16 A > G, and c.1000–22 C > T. We conducted a review of the patient’s previous kidney biopsy findings, which demonstrated the presence of lamellated inclusion bodies in electron microscopy. Remarkably, both the monozygotic twin sister and her son exhibited the same genetic mutation. Enzyme replacement therapy was initiated for the patient. Her kidney function decreased throughout a thorough 2-year follow-up period, while there was a slight decrease in the left ventricular mass index.ConclusionsThis is the first reported case of female monozygotic twins with the CIH variants representing cardiac, cerebrovascular, and renal manifestations suggestive of Fabry disease.

Insights into clinical phenotypes and treatment responses in a Small cohort of Taiwanese patients with SCN1A variants: A Preliminary study

BackgroundSCN1A channelopathy is the most well-known cause for epileptic encephalopathies and contributes to a wide phenotypic spectrum. The variable expressivity is troublesome for the interpretation of clinical significance and prognoses. To investigate the clinical manifestations, medications and outcomes of patients with SCN1A channelopathies, we conducted this observation retrospective study in Taiwan. MethodsA cohort consisting of 16 patients (5 males and 11 females) from multiple centers with identified SCN1A variants was investigated and phenotypically relevant factors were recorded. The variants were identified using NGS and confirmed by Sanger sequencing. A panel of 90 epileptic-related genes was used to identify SCN1A variants and to evaluate some of the potential SCN1A modifier genes. ResultsThe mean age of seizure onset was 10.4 months. Twelve of the sixteen patients (75%) had different degrees of neurocognitive sequela and psychobehavioral comorbidity in our cohort. Cognitive impairment was noted in all ten patients with Dravet syndrome (DS) and in two of the patients with non-DS phenotypes. A lower response rate to medications was also noted in patients with DS. Notably, a medication-specific tendency towards valproic acid (VPA), clobazam (CLB), and levetiracetam (LEV) was observed, revealing the effective pharmacotherapies for SCN1A-related seizures. An asymptomatic carrier with a reported pathogenic SCN1A variant was reviewed along with her monozygotic twin sister with DS. Nine novel SCN1A mutations are herein reported, eight of which being classified as pathogenic. ConclusionOur study revealed unfavorable outcomes for patients with SCN1A variants. Some patients with SCN1A channelopathy showed specific responsiveness to the pharmacotherapies previously either recommended or contraindicated for these patients. Our study also expands the genotype and provides valuable prognostic insights in patients with SCN1A channelopathy.

Monogenic Autoinflammatory Disease Due to Blau Syndrome with Nucleotide Oligomerization Domain 2 Gene Mutation in an Indian Family

Background: Blau syndrome is a monogenic disease resulting from mutations in nucleotide oligomerization domain 2 (NOD2) and is phenotypically characterized by a triad of dermatitis, arthritis, and uveitis. We report Blau syndrome in a child who had been symptomatic for years, without the typical clinical triad. Clinical Description: A 7-year-old girl child presented with bilateral knee, wrist, and ankle joint swelling since the age of 2 years. She had recently developed a rash on the body. Her mother, mother’s identical twin sister, and the latter’s 5-year-old daughter had similar joint pain and swellings since childhood. In view of the strong positive family history of polyarthritis, monogenic cause of arthritis was suspected. Management and Outcome: Complete blood count was unremarkable. Erythrocyte sedimentation rate was 20 mm at C-reactive protein was 36 mg/L, antinuclear antibody and rheumatoid arthritis factor were negative. X-ray of the knee joints and wrist joints showed soft-tissue swellings around the knee and lumbar scoliosis. A heterozygous pathogenic variant in NOD2 gene confirmed the diagnosis of Blau syndrome. After receiving the genetic report, the girl was started on prednisolone and weekly methotrexate. Conclusion: Early-onset arthritis, with recurrent episodes of fever, is not to be ignored if autoimmune markers are negative. Knowledge about the clinical features of autoinflammatory diseases and the spectrum of NOD2 variants will enable physicians to carry out specific investigations, especially genetic analysis for confirmation of the diagnosis and hence administer the right treatment.

A female patient carrying a novel DMD mutation with non-random X-chromosome inactivation from a DMD family

ObjectiveTo analyze the clinical phenotype and genetic characteristics of a female proband carrying a novel mutation in the DMD gene with non-random X-chromosome inactivation in a large pedigree with pseudohypertrophic muscular dystrophy.MethodsClinical information of the female proband, her monozygotic twin sister, and other family members were collected. Potential pathogenic variants were detected with Multiplex Ligation-dependent Probe Amplification (MLPA) and whole-exome sequencing (WES). Methylation-sensitive restriction enzyme (HhaI) was employed for X-chromosome inactivation analysis.ResultsThe proband was a female over 5 years old, displayed clinical manifestations such as elevated creatine kinase (CK) levels and mild calf muscle hypertrophy. Her monozygotic twin sister exhibited normal CK levels and motor ability. Her uncle and cousin had a history of DMD. WES revealed that the proband carried a novel variant in the DMD (OMIM: 300,377) gene: NM_004006.3: c.3051_3053dup; NP_003997.2: p.Tyr1018*. In this pedigree, five out of six female members were carriers of this variant, while the cousin and uncle were hemizygous for this variant. X-chromosome inactivation analysis suggested non-random inactivation in the proband.ConclusionThe c.3051_3053dup (p.Tyr1018*) variant in the DMD gene is considered to be the pathogenic variant significantly associated with the clinical phenotype of the proband, her cousin, and her uncle within this family. Integrating genetic testing with clinical phenotype assessment can be a valuable tool for physicians in the diagnosis of progressive muscular dystrophies, such as Becker muscular dystrophy (BMD) and Duchenne muscular dystrophy (DMD).

Monozygotic twin sisters differ in voice quality: Acoustic analysis of the diphthong [‘oj] produced by Brazilian native speakers

Identical twins challenge individual voice recognition applied in communication, criminal investigation, and health technologies. The similarities between siblings are due to the genetic heritage that produced either their vocal tract or the psychological processes acting since birth. To contribute to a precise individual identification by voice, we tested the hypothesis that even MZ siblings would differ in the spectral distribution of formants and sound quality. We recorded 86 same-sex twin pairs (71 MZ, 15 DZ 30 ± 12 years old) saying the Portuguese verse of “Hi, my name is (Pedro or Ana).” We trimmed the diphthong Ój (“Hi”) and measured f0, F1-F4 formants, jitter, shimmer, and Harmonic-to-noise ratio (HNR). As the male sampling was small, we compared only female twins using the Wilcoxon-matched test, the intrapair Correlation Coefficient (ICC), and GLMM models. On average, [Ój] lasted 0.24 ± 0.07 s, and f0 ranged from 469 to 510 kHz according to sex. We found no differences between the MZ or DZ sisters in any acoustic parameter, besides F1 for MZ ones. Also, MZ sisters were more alike (F1, jitter, HNR, weak; F3, F4 moderate) than DZ (only F1 high ICC). The interaction zygosity × age affected intrapair similarity, the older the sisters, the greater their differences. Short voice segments, like the diphthong [Ój], may not be good for differentiating identical twins but provide insights to discussion; F2, F4, and shimmer should be investigated in future studies considering males, younger participants, and other vocal expressions.

Bullous Variant of Central Serous Chorioretinopathy in Goodpasture's Disease - A Case Report and Review of Literature.

To describe a case of bullous variant of central serous chorioretinopathy (CSR) in Goodpasture's disease (GD) compared to an identical twin without GD, and summarize the literature on ocular manifestations of GD. Interventional/observational case report and literature review. A 46-year-old white female with a history of GD presented with decreased vision. She demonstrated bilateral multifocal pigment epithelial detachments and a large inferior exudative retinal detachment in the left eye consistent with bilateral CSR with bullous variant CSR (bvCSR) in the left eye. Despite treatment, her disease remained refractory, with final VA of 20/200 in the left eye. The patient's identical twin sister did not have GD and demonstrated milder CSR on presentation with a more typical, self-limited disease course. Her final VA was 20/20 bilaterally. GD is associated with severe manifestations of CSR (exudative RD). Additional studies focusing on the association between GD and CSR severity may be of interest.

Early-onset gynecological tumors in DNA repair-deficient xeroderma pigmentosum group C patients: a case series

BackgroundXeroderma pigmentosum (XP) is a group of rare hereditary disorders with highly increased risk of skin tumors due to defective DNA repair. Recently we reported 34-fold increased risk of internal tumors in XP patients in comparison with general population. The molecular data and clinical practice on the internal tumors treatment in XP patients is limited and scarcely represented in the medical literature. In this work, we describe young patients with constitutive biallelic deactivation of the XPC gene developing gynecological tumors with somatic DICER1 mutations.MethodsWhole genome sequencing was used to analyze in detail somatic mutational landscape and driver events of these rare tumors.ResultsWe describe five early-onset gynecological tumors in four xeroderma pigmentosum group C (XP-C) young patients (11 to 19 years old) including vaginal embryonal rhabdomyosarcomas in monozygotic twin sisters, juvenile granulosa-cell tumor of the ovary and poorly differentiated stage IA Sertoli-Leydig cell tumor in 19-years old patient, and FIGO stage IC1 tumor of ovary in 13-years old patient. XP-C ovarian tumors harbor 4.4 times more single base substitutions than sporadic tissue-matched cancers and demonstrate XP-C specific mutation signature with strong transcriptional bias indicating inability of the cells to repair bulky DNA lesions of unknown etiology. A special mode of treatment was applied to avoid usage of chemotherapy which is toxic for XP patients.ConclusionsXP-C status should be accounted for prevention and specific treatment of gynecological tumors in young DNA repair-deficient XP patients.

A novel heterozygous ZBTB18 missense mutation in a family with non-syndromic intellectual disability.

Intellectual disability (ID) is a common neurodevelopmental disorder characterized by significantly impaired adaptive behavior and cognitive capacity. High throughput sequencing approaches have revealed the genetic etiologies for 25-50% of ID patients, while inherited genetic mutations were detected in <5% cases. Here, we investigated the genetic cause for non-syndromic ID in a Han Chinese family. Whole genome sequencing was performed on identical twin sisters diagnosed with ID, their respective children, and their asymptomatic parents. Data was filtered for rare variants, and in silico prediction tools were used to establish pathogenic alleles. Candidate mutations were validated by Sanger sequencing. In silico modeling was used to evaluate the mutation's effects on the protein encoded by a candidate coding gene. A novel heterozygous variant in the ZBTB18 gene c.1323C>G (p.His441Gln) was identified. This variant co-segregated with affected individuals in an autosomal dominant pattern and was not detected in asymptomatic family members. Molecular studies reveal that a p.His441Gln substitution disrupts zinc binding within the second zinc finger and disrupts the capacity for ZBTB18 to bind DNA. This is the first report of an inherited ZBTB18 mutation for ID. This study further validates WGS for the accurate molecular diagnosis of ID.

Rare variants in the MECP2 gene in girls with central precocious puberty: a translational cohort study

Identification of genetic causes of central precocious puberty have revealed epigenetic mechanisms as regulators of human pubertal timing. MECP2, an X-linked gene, encodes a chromatin-associated protein with a role in gene transcription. MECP2 loss-of-function mutations usually cause Rett syndrome, a severe neurodevelopmental disorder. Early pubertal development has been shown in several patients with Rett syndrome. The aim of this study was to explore whether MECP2 variants are associated with an idiopathic central precocious puberty phenotype. In this translational cohort study, participants were recruited from seven tertiary centres from five countries (Brazil, Spain, France, the USA, and the UK). Patients with idiopathic central precocious puberty were investigated for rare potentially damaging variants in the MECP2 gene, to assess whether MECP2 might contribute to the cause of central precocious puberty. Inclusion criteria were the development of progressive pubertal signs (Tanner stage 2) before the age of 8 years in girls and 9 years in boys and basal or GnRH-stimulated LH pubertal concentrations. Exclusion criteria were the diagnosis of peripheral precocious puberty and the presence of any recognised cause of central precocious puberty (CNS lesions, known monogenic causes, genetic syndromes, or early exposure to sex steroids). All patients included were followed up at the outpatient clinics of participating academic centres. We used high-throughput sequencing in 133 patients and Sanger sequencing of MECP2 in an additional 271 patients. Hypothalamic expression of Mecp2 and colocalisation with GnRH neurons were determined in mice to show expression of Mecp2 in key nuclei related to pubertal timing regulation. Between Jun 15, 2020, and Jun 15, 2022, 404 patients with idiopathic central precocious puberty (383 [95%] girls and 21 [5%] boys; 261 [65%] sporadic cases and 143 [35%] familial cases from 134 unrelated families) were enrolled and assessed. We identified three rare heterozygous likely damaging coding variants in MECP2 in five girls: a de novo missense variant (Arg97Cys) in two monozygotic twin sisters with central precocious puberty and microcephaly; a de novo missense variant (Ser176Arg) in one girl with sporadic central precocious puberty, obesity, and autism; and an insertion (Ala6_Ala8dup) in two unrelated girls with sporadic central precocious puberty. Additionally, we identified one rare heterozygous 3'UTR MECP2 insertion (36_37insT) in two unrelated girls with sporadic central precocious puberty. None of them manifested Rett syndrome. Mecp2 protein colocalised with GnRH expression in hypothalamic nuclei responsible for GnRH regulation in mice. We identified rare MECP2 variants in girls with central precocious puberty, with or without mild neurodevelopmental abnormalities. MECP2 might have a role in the hypothalamic control of human pubertal timing, adding to the evidence of involvement of epigenetic and genetic mechanisms in this crucial biological process. Fundação de Amparo à Pesquisa do Estado de São Paulo, Conselho Nacional de Desenvolvimento Científico e Tecnológico, and the Wellcome Trust.

Monozygotic twin cases of endometriosis with Glanzmann thrombasthenia: a case report and review of literature

BackgroundGlanzmann thrombasthenia (GT) is a rare bleeding disorder with a high prevalence in communities where consanguineous marriages are mainstream. Endometriosis is a chronic inflammatory disease, and its risk increases in women with menstrual periods of longer than six days. The phenotypic expression of endometriosis is determined by the frequency and rate of the menstrual flow, as well as genetic and environmental factors.Result and case presentation14-year-old monozygotic twin sisters with GT who developed ovarian endometriosis were referred to Hazrat Rasoul Hospital due to severe dysmenorrhea. In ultrasonic examination, endometrioma cysts were reported in both patients. They both went under endometrioma cystectomy, and the bleeding was managed using antifibrinolytic drugs, followed by recombinant activated coagulation factor VII. Both were discharged after 3 days. In the ultrasound examination performed one year after the surgery, ovaries were normal in the first twin, while the second twin had a 28 × 30 hemorrhagic cyst in the left ovary.Discussion and conclusionMenstrual bleeding and genetic factors are two theories that could be related to GT and endometriosis association, and GT could be considered a risk factor for endometriosis.

Hyper‐IgE syndrome presenting with early life craniosynostosis in monozygotic twin sisters

<scp>Hyper‐IgE</scp> syndrome presenting with early life craniosynostosis in monozygotic twin sisters

Allergic bronchopulmonary aspergillosis in identical twins: Effectiveness of dupilumab

Allergic bronchopulmonary aspergillosis in identical twins: Effectiveness of dupilumab

From the Wright Brothers to the A380: Developing Transplantation Takes Teams of Teams.

From the Wright Brothers to the A380: Developing Transplantation Takes Teams of Teams.

RF14 | PSAT120 X-Linked Central Precocious Puberty Associated with MECP2 Defects

Abstract Methyl-CpG-binding protein 2 (MECP2) is a chromatin-associated protein that can both activate and repress transcription, playing an essential role in neuronal maturation. MECP2 is encoded by an X-linked gene (chromosome Xq28) with high expression in the brain, including the hypothalamic region. Loss-of-function mutations in MECP2 are usually associated with Rett syndrome, a rare genetic disorder characterized by normal early development followed by regression of acquired skills, such as purposeful hand movements and the ability to communicate, repetitive hand stereotypies, slowed brain growth, seizures, and intellectual disability with female predominance. Notably, early pubertal development (early thelarche, pubarche and, less often, menarche) has been demonstrated in girls with Rett syndrome. In this original study, a total of 329 CPP patients (308 girls and 21 boys) were investigated for MECP2 defects. Familial cases were identified in 38% of this CPP cohort. First, 129 CPP patients were enrolled for multigene sequencing studies (whole-exome sequencing n=58; targeted gene sequencing n=71) as part of genetic investigations based on large-scale approaches. Three rare heterozygous sequence variants predicted to be deleterious in MECP2 gene were identified in 5 girls from 4 unrelated families with CPP: the p.Arg97Cys de novo missense variant in two monozygotic twin sisters with CPP and microcephaly; the p.Ser176Arg de novo missense variant in one girl with sporadic CPP, obesity and autism; and the p.Ala6_Ala8dup insertion in two unrelated girls with sporadic CPP (one with a maternally inherited variant). To expand the investigation for potentially damaging sequence variants of MECP2, a larger multiethnic cohort of 200 CPP patients was further analyzed through Sanger sequencing. One rare heterozygous 3'UTR insertion in MECP2 (c.*36_*37insT) was identified in two unrelated girls with sporadic CPP (one with a maternally inherited variant and other with a de novo variant). None of these MECP2 variants have been previously reported in Rett syndrome cases. The girls with CPP associated with MECP2 defects did not manifest typical Rett syndrome. The three patients with more deleterious MECP2 variants, according to in silico prediction tools, had neurobehavioral phenotypes, likely corresponding to a genotype-phenotype correlation. Immunohistochemistry and immunofluorescence studies were performed in pubertal female mice. Abundant staining for Mecp2 was demonstrated in multiple hypothalamic nuclei (arcuate, suprachiasmatic, and paraventricular) and in the median eminence. Co-localization of Mecp2 and GnRH within GnRH neurons was suggested in double labelling experiments. Hence, Mecp2 expression was demonstrated in key hypothalamic nuclei responsible for GnRH regulation in female mice. In conclusion, we have identified rare dominant MECP2 defects in multiple unrelated girls with CPP with or without mild neurodevelopmental abnormalities, revealing a new X-linked form of premature reactivation of the hypothalamic-pituitary-gonadal axis. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m., Sunday, June 12, 2022 12:30 p.m. - 12:35 p.m.

ONE21 technique for an individualized assessment and treatment of upper face wrinkles in five pairs of identical twins with IncobotulinumtoxinA.

Facial aging is a complex process, which, beyond a genetic predisposition, involves both physical and environmental factors. Even identical twins with the same genetic load may differ substantially in facial wrinkles and aging, demanding a personalized treatment approach. To demonstrate the ONE21 technique as an excellent tool to a customized assessment and IncobotulinuntoxinA treatment to address phenotype discordances and epigenetic drifts in identical twins, expressed by different patterns of upper face muscle contractions and wrinkles intensity. Five pairs of identical Caucasian twin sisters, from 30 to 45years of age, were evaluated for hyperfunctional upper facial wrinkles (forehead, glabella, and periorbital), assessing the individual anatomy, muscle function and habitual facial movements of each patient. All the subjects were treated with the ONE21 technique using IncobotulinumtoxinA and reevaluated 30days after the procedure. Though the clinical-anatomical pattern of the forehead contraction was similar between the pairs, the strength of the muscles, the number and depth of wrinkles differed. This varied presentation demanded distinct points of distribution and dosages of incobotulinumtoxinA for all the twins, according to the ONE21 approach. The results 30days after treatment were satisfactory in all the subjects. The ONE21 technique allows an objective and careful evaluation of the wrinkles of the upper face, based on an individualized assessment, which may vary even in identical twins.

Race and Identity in Brit Bennett’s The Vanishing Half

Race and identity transformation have been overarching themes in the works of African American writers. Brit Bennett’s The Vanishing Half (2020) is one fictional work that deals with identical twin sisters: Desiree and Stella Vignes. They are two light-skinned Black sisters who have chosen or rebuilt their identities based on the needs that allow them to live in peace among their communities. This study attempts to trace the importance of race and identity for the African Americans through exploring the lives of these twin sisters who leave their hometown. Through postcolonial critical concepts of identity and race, this research sheds light on the reasons behind the sisters’ decisions to keep or shed their Black identity, as well as their community’s influence on their decision to leave their hometown. This study found that the choices of race and identity the sisters made earlier in their lives identified their fate and established a path for their children. Desiree prefers to maintain her identity by marrying a Black man, and Stella sees her interest in marrying a White man and keeping her past hidden. Kennedy, Stella’s daughter with a White man, and Jude, Desiree’s daughter with a Black man, adhere to their parent’s beliefs regarding race and identity. However, Stella and Desiree still long for their origin and home, and ultimately, they gather again at home they left together.

A Longitudinal 3D Investigation on Facial Similarity among Two Monozygotic Twins in Their First Childhood: An Application of the 3D-3D Facial Superimposition Technique.

Children affected by orofacial disorders mix functional alterations with morphological problems, and suitable techniques should be devised for their analysis. Stereophotogrammetry and 3D-3D facial superimposition have already proven to reliably assess morphological differences even between twin siblings, separating the effect of genetic and environmental factors. However, little information is available about twin babies. We longitudinally analyzed a couple of healthy monozygotic twin sisters aged 6 months to 5 years (height time points). The entire 3D facial models of the two sisters were registered according to the least point-to-point distance, and the relevant RMS (root mean square) distance between the facial models was calculated at each time and compared with reference data recorded from adult twins (Mann-Whitney test, p < 0.05). RMS values in the twin sisters were on average 1.18 ± 0.21 mm, and 1.86 ± 0.53 mm in adults, with a significant difference (p < 0.01). Results showed that twins are more similar in early childhood when environmental factors are supposed to have not influenced facial morphology sufficiently. Additionally, the technique seems adequate to detect even small differences: the faces of the twin sisters were not fully identical. 3D-3D facial superimposition techniques can objectively quantify facial dissimilarity even in monozygotic twins. The method may be applied to the faces of twins discordant for some orofacial and maxillofacial pathology and potentially separate genetic and environmental factors.

Post COVID-19 Anterior Cruciate Ligament (ACL) Tear in Twin Sisters After Re-starting Professional Futsal Exercises: A ‎Case Report

Awareness of the long-term COVID-19 complications is of significant importance in reducing its morbidity through the implementation of timely interventional programs. In this study, we report an anterior cruciate ligament (ACL) tear in athlete identical twin sisters almost 2 months after the COVID-19 infection. The patients had 15 years of professional futsal experience and showed no obvious risk factors for an ACL tear, such as familial history, abnormal menstruation, oral contraceptive consumption, reduced intercondylar notch, or increased tibial slope. However, they experienced a non-contact complete ACL tear within 1 month of re-participation in professional exercise after the COVID-19 infection. Both patients reported a sense of muscle weakness during the COVID-19 recovery period, and ligamentous laxity was obvious according to the clinical examination and the Beighton criteria. This report shows persistent muscle weakness after the COVID-19 infection that could increase the risk of ACL injury in female athletes and suggests taking a prophylactic rehabilitating program to prevent its catastrophic consequences.

Computational identification of personal genetic variants in an identical twin sisters' family

Nowadays, scientists still have a limited understanding of how much genetic variation exists between identical twins. This study aims to analyse genotypic differences between identical twins and annotate the functional variants. We employed the 23andMe genotyping service to compare the genomes of twin sisters and their family members. With 162,400 SNPs genotyped at the autosomes, we found that there were 64,083 (10.26%) differences between one of the twins and their sibling brothers, while only 2530 differences (0.41%) existed between twin sisters. In total, among the 1974 nonsynonymous variants genotyped, excluding 'no calls,' only 17 shared nonsynonymous pathogenic variants between twin sisters were identified. The 16 pathogenic variants harboured genes are enriched with six significant terms associated with liver function and metabolic pathways. Our research could provide insight for physicians conducting studies related to genetic variations and personalised treatment of genetic disorders of identical twins.