Recurring germline mosaicism in a family due to reversion of an inherited derivative chromosome 8 from an 8;21 translocation with interstitial telomeric sequences.

BACKGROUND: Mosaicism for chromosomal structural abnormalities, other than marker or ring chromosomes, is rarely inherited. METHODS: We performed cytogenetics studies and breakpoint analyses on a family with transmission of mosaicism for a derivative chromosome 8 (der(8)), resulting from an unbalanced translocation between the long arms of chromosomes 8 and 21 over three generations. RESULTS: The proband and his maternal half-sister had mosaicism for a der(8) cell line leading to trisomy of the distal 21q, and both had Down syndrome phenotypic features. Mosaicism for a cell line with the der(8) and a normal cell line was also detected in a maternal half-cousin. The der(8) was inherited from the maternal grandmother who had four abnormal cell lines containing the der(8), in addition to a normal cell line. One maternal half-aunt had the der(8) and an isodicentric chromosome 21 (idic(21)). Sequencing studies revealed microhomologies at the junctures of the der(8) and idic(21) in the half-aunt, suggesting a replicative mechanism in the rearrangement formation. Furthermore, interstitial telomeric sequences (ITS) were identified in the juncture between chromosomes 8 and 21 in the der(8). CONCLUSION: Mosaicism in the proband, his half-sister and half-cousin resulting from loss of chromosome 21 material from the der(8) appears to be a postzygotic event due to the genomic instability of ITS and associated with selective growth advantage of normal cells. The reversion of the inherited der(8) to a normal chromosome 8 in this family resembles revertant mosaicism of point mutations. We propose that ITS could mediate recurring revertant mosaicism for some constitutional chromosomal structural abnormalities.

Germline HPF1 retrogene insertion in RB1 gene involved in cancer predisposition.

About half of the human genome is composed of repeated sequences derived from mobile elements, mainly retrotransposons, generally without pathogenic effect. Familial forms of retinoblastoma are caused by germline pathogenic variants in RB1 gene. Here, we describe a family with retinoblastoma affecting a father and his son. No pathogenic variant was identified after DNA analysis of RB1 gene coding sequence and exon-intron junctions. However, RB1 mRNA analysis showed a chimeric transcript with insertion of 114 nucleotides from HPF1 gene inside RB1 gene. This chimeric transcript led to an insertion of 38 amino acids in functional domain of retinoblastoma protein. Subsequent DNA analysis in RB1 intron 17 revealed the presence of a full-length HPF1 retrogene insertion in opposite orientation. Functional assay shows that this insertion has a deleterious impact on retinoblastoma protein function. This is the first report of a full-length retrogene insertion involved in human Mendelian disease leading to a chimeric transcript and a non-functional chimeric protein. Some retrogene insertions may be missed by standard diagnostic genetic testing, so contribution of retrogene insertions to human disease may be underestimated. The increasing use of whole genome sequencing in diagnostic settings will help to get a more comprehensive view of retrogenes.

Consanguinity and associated perinatal outcomes, including stillbirth.

BACKGROUND: Consanguinity defined as the sexual union between two related individuals has been previously an infrequent practice in Australia, but recently there has been migration from countries with widespread practice of consanguinity. There is limited and conflicting evidence in the literature that suggests consanguinity to be associated with adverse obstetric outcomes. AIM: To assess the effect of consanguinity on perinatal outcomes. MATERIALS AND METHODS: A retrospective analysis of singleton births over a ten-year period at an Australian tertiary hospital. The data were extracted from the hospital obstetric database and analysed for an association between consanguinity and perinatal outcomes, including stillbirth. Main outcome measures were stillbirth, threatened premature labour, fetal congenital abnormality, perinatal mortality and neonatal outcomes. RESULTS: There were 46 399 singleton births recorded over the ten-year study period, and 44 004 had consanguinity data available. The overall consanguinity rate was 5.5% (n = 2565), which remained consistent over the study period at our institution. Consanguinity was associated with higher rate of threatened premature labour (5.6% vs 4.7%, P = 0.003), fetal congenital abnormality (4.2% vs 3.1%, P = 0.004), perinatal mortality (2.4% vs 1.0%, P < 0.001) and reduced risk of hypertension in pregnancy (5.3% vs 3.4%, P < 0.001). Consanguinity was an independent risk factor for stillbirth with a relative risk of 2.88 (P < 0.001, 95% CI 1.98, 4.18). CONCLUSION: Women from consanguineous relationships are at higher risk of adverse perinatal outcomes, including stillbirth. Given the 5% prevalence of consanguinity in our obstetric population, these findings have significant implications for preconception counselling, obstetric care and health resource allocation.

The Association between Family History of Lung Cancer and Development of Lung Cancer: Analysis from the KoGES Data in Korea.

Comprehensive analyses of the association between a family history of lung cancer and lung cancer risk are limited, especially in the Korean population. We used baseline data from the Korean Genome and Epidemiology Study, conducted between 2001 and 2013. This study enrolled 198,980 individuals. Lung cancer diagnoses and family histories were determined using questionnaires. Multivariable logistic regression analysis was performed to evaluate the effect of family history on the risk of lung cancer. Of 198,980 individuals, 6296 (3.2%) and 140 (0.1%) had a family history of lung cancer and lung cancer, respectively. Individuals with a family history of lung cancer in first-degree relatives (FDRs) had a higher risk of lung cancer development than those without (adjusted odds ratio [aOR] = 2.28, 95% confidence interval [CI] = 1.11-4.66). This was more pronounced in young individuals (<60 years) who had affected relatives diagnosed with lung cancer before the age of 60 years (aOR = 3.77, 95% CI = 1.19-11.88). In subgroup analyses, this association was more evident in women, never smokers, and young individuals. A family history of lung cancer, especially in FDRs, is a significant risk factor for lung cancer development in Korea.

[Genetic factors associated with long COVID]. / Factores genéticos asociados a long COVID.

INTRODUCTION: The variability in expression and evolution of COVID is not completely explained by clinical factors. In fact, genetic factors play an important role. Moreover, it is unknown whether the genetic factor that contribute to susceptibility and severity are also involved in the onset and evolution of long-COVID. The objective of this review is to gather information from literature to understand which genetic factors are involved in the onset of persistent COVID. MATERIAL AND METHODS: Systematic review in PubMed and bioRxiv and medRxiv repositories based on MeSH-descriptors and MeSH-terms related to COVID and genetic factors. Using these terms 2715 articles were pooled. An initial screening performed by authors independently, selected 205 articles of interest. A final deeper screening a total of 85 articles were chosen for complete reading and summarized in this review. RESULTS: Although ACE2 and TMPSS6 are involved in COVID susceptibility, their involvement in long-COVID has not been found. On the other hand, the severity of the disease and the onset of long-COVID has been associated with different genes involved in the inflammatory and immune response. Particularly interesting has been the association found with the FOXP4 locus. CONCLUSIONS: Although studies on long-COVID are insufficient to fully comprehend the cause, it is clear that the current identified genetic factors do not fully explain the progression and onset of long-COVID. Other factors such as polygenic action, pleiotropic genes, the microbiota and epigenetic changes must be considered and studied.

Differences in clinical and genetic characteristics between early- and late-onset narcolepsy in a Han Chinese cohort.

Early- and late-onset narcolepsy constitutes two distinct diagnostic subgroups. However, it is not clear whether symptomology and genetic risk factors differ between early- and late-onset narcoleptics. This study compared clinical data and single-nucleotide polymorphisms (SNPs) between early- and late-onset patients in a large cohort of 899 Han Chinese narcolepsy patients. Blood, cerebrospinal fluid, and clinical data were prospectively collected from patients, and patients were genotyped for 40 previously reported narcolepsy risk-conferring SNPs. Genetic risk scores (GRSs), associations of five different sets of SNPs (GRS1-GRS5) with early- and late-onset narcolepsy, were evaluated using logistic regression and receiver operating characteristic curves. Mean sleep latency was significantly shorter in early-onset cases than in late-onset cases. Symptom severity was greater among late-onset patients, with higher rates of sleep paralysis, hypnagogic hallucinations, health-related quality of life impairment, and concurrent presentation with four or more symptoms. Hypocretin levels did not differ significantly between early- and late-onset cases. Only rs3181077 (CCR1/CCR3) and rs9274477 (HLA-DQB1) were more prevalent among early-onset cases. Only GRS1 (26 SNPs; OR = 1.513, 95% CI: 0.893-2.585; P < 0.05) and GRS5 (6 SNPs; OR = 1.893, 95% CI: 1.204-2.993; P < 0.05) were associated with early-onset narcolepsy, with areas under the receiver operating characteristic curves of 0.731 and 0.732, respectively. Neither GRS1 nor GRS5 included SNPs in HLA regions. Our results indicate that symptomology and genetic risk factors differ between early- and late-onset narcolepsy. This protocol was approved by the Institutional Review Board (IRB) Panels on Medical Human Subjects at Peking University People's Hospital, China (approval No. Yuanlunshenlinyi 86) in October 2011.

Reporte de una nueva mutación en Colombia: un paciente con síndrome de Kabuki / Report of a new mutation in Colombia in a patient with Kabuki Syndrome

RESUMEN Introducción: el síndrome de Kabuki es un desorden pediátrico congénito de origen genético. Los pacientes presentan anormalidades morfológicas como paladar hendido, globos oculares prominentes, eversión del tercio externo del párpado inferior, persistencia de cojinetes dactilares y anormalidades vertebrales. La mayoría cursan con dificultad del aprendizaje. Objetivo: reportar un caso pediátrico de síndrome de Kabuki y fomentar el reconocimiento del fenotipo asociado para facilitar su diagnóstico oportuno. Caso Clínico: paciente masculino de 9 años con características clínicas y diagnóstico genético probable para síndrome de Kabuki. Presenta fisuras palpebrales largas, paladar en ojival, baja implantación auricular, persistencia de almohadillas en pulpejos de dedos, talla baja y colangitis esclerosante primaria. Conclusión: el síndrome de Kabuki tipo 1, se caracteriza por alteraciones faciales que inducen una sospecha diagnóstica. El paciente reportado presentaba múltiples hallazgos descritos. En el estudio genético realizado se considera la variante identificada en el gen KMT2D, probablemente patogénica.

SUMMARY Introduction: Kabuki Syndrome is a pediatric congenital disorder of genetic origin. These patients present morphological abnormalities such as cleft palate, prominent eyeballs, persistence of fingerpads, and vertebral abnormalities. Most also have learning difficulty. Objective: Report a pediatric case of Kabuki Syndrome to increase the recognition of the phenotype associated with it and the likelihood of a diagnosis with the use of a clinical case report. Case report: A nine-year-old male patient with clinical characteristics and probable genetic diagnosis of Kabuki Syndrome. He exhibits elongated eyelids, cleft palate, low auricular implantation, persistence of fingerpads, reduced height, and primary sclerosing cholangitis. Conclusion: Diagnostic suspicion of type one Kabuki Syndrome is characterized mainly by facial alterations. The following patient presents multiple distinctive characteristics described in literature. A genetic study considers the gene KMT2D a possible pathologic genetic variant of the disease.

Consanguinity and Inbreeding Coefficient F in Aligarh city, India: A Cross Sectional Study

Objective: To determine the coefficient of inbreeding of consanguinity (F) and its correlates in Aligarh city, India. Material and Methods: Cross sectional household survey with a sample size of 2000 (1600 non-consanguineous and 400 consanguineous couples) using systematic random sampling. Researcher conducted the study by visiting every tenth household of every tenth ward of Aligarh city. Information was recorded on a pre-tested questionnaire, which had questions pertaining to religion, details regarding relationship between couples (consanguineous / non consanguineous marriage), type of consanguinity (first cousin/second cousin/third cousin), level of education and occupation (a proxy for socioeconomic status). Descriptive statistics, Chi-square, and multivariate logistic regression were used. Results: Multivariate logistic regression analysis showed that Islam (p<0.001) and Christianity (p<0.001) were significantly associated with consanguinity. Private employment with (-) B value (p<0.001) showed a significant association of the variable with non-consanguineous group. Coefficient of inbreeding for the present study was 0.0538, highest reported from any part of India. Conclusion: Consanguinity is a prevailing problem in Aligarh city, India. Evidence based guidelines needed. Information ­ education ­ communication and pre-marital counseling suggested to make population aware of the consequences of consanguinity and to help couples make a decision.

Leprosy: review of the epidemiological, clinical, and etiopathogenic aspects - Part 1

Leprosy is caused by Mycobacterium leprae and has been known since biblical times. It is still endemic in many regions of the world and a public health problem in Brazil. The prevalence rate in 2011 reached 1.54 cases per 10,000 inhabitants in Brazil. The mechanism of transmission of leprosy consists of prolonged close contact between susceptible and genetically predisposed individuals and untreated multibacillary patients. Transmission occurs through inhalation of bacilli present in upper airway secretion. The nasal mucosa is the main entry or exit route of M. leprae. The deeper understanding of the structural and biological characteristics of M. leprae, the sequencing of its genome, along with the advances in understanding the mechanisms of host immune response against the bacilli, dependent on genetic susceptibility, have contributed to the understanding of the pathogenesis, variations in the clinical characteristics, and progression of the disease. This article aims to update dermatologist on epidemiological, clinical, and etiopathogenic leprosy aspects.

De Gregor Mendel y la docencia sin licencia / Gregor Mendel: teaching without licence

Gregor Mendel, padre de la genética, fracasó en su intento por obtener la licenciatura que lo acreditara como profesor, pero su fracaso fue el origen de su posterior triunfo histórico. La fidelidad de Mendel hacia la defensa del preformismo fue la base de los experimentos en Pisum sativum. Su historia demuestra que la licencia no necesariamente certifica al verdadero maestro y que el buen maestro no requiere de licencia...

Gregor Mendel, father of Genetics, failed in his attempt to obtain an accredited degree as a teacher, but his failure was the origin of a subsequent historical triumph. Mendel’s faithfulness toward the defense of preformationism was the basis of the experiments in Pisum sativum. His history shows that the license does not necessarily certify the true master, and that the good teacher does not require licensing...