We build a model of storage of well-defined positional information in probabilistic sequence patterns. Once a pattern is defined, it is possible to judge the effect of any mutation in it. We show that the frequency of...We build a model of storage of well-defined positional information in probabilistic sequence patterns. Once a pattern is defined, it is possible to judge the effect of any mutation in it. We show that the frequency of beneficial mutations can be high in general and the same mutation can be either advantageous or deleterious depending on the pattern’s context. The model allows to treat positional information as a physical quantity, formulate its conservation law and to model its continuous evolution in a whole genome, with meaningful applications of basic physical principles such as optimal efficiency and channel capacity. A plausible example of optimal solution analytically describes phase transitions-like behavior. The model shows that, in principle, it is possible to store error-free information on sequences with arbitrary low conservation. The described theoretical framework allows one to approach from novel general perspectives such long-standing paradoxes as excessive junk DNA in large genomes or the corresponding G- and C-values paradoxes. We also expect it to have an effect on a number of fundamental concepts in population genetics including the neutral theory, cost-of-selection dilemma, error catastrophe and others.展开更多
Objectives: The currently available methods for rapid prenatal diagnosis of common chromosomal aneuploidies are either Interphase-Fluorescence in Situ Hybridisation (I-FISH) or Quanti- tative Fluorescent Polymerase Ch...Objectives: The currently available methods for rapid prenatal diagnosis of common chromosomal aneuploidies are either Interphase-Fluorescence in Situ Hybridisation (I-FISH) or Quanti- tative Fluorescent Polymerase Chain Reaction (QF-PCR). QF-PCR represents a rapid, high throughput, cost-effective alternative for Interphase-FISH. The objective of the study was to evaluate the performance of QF-PCR, as a molecular-based technique for the detection of chromosome 21, 18 and 13 copy numbers. Study design: A retrospective cohort of 163 samples referred for screening of common chromosomal aneuploidies was blindly tested for chromosome 21, 18 and 13 copy numbers using QF-PCR and the results were compared with those of conventional cytogenetic analysis. Results: QF-PCR demonstrated optimal sensitivity and specificity (100%) for non mosaic trisomies. QF-PCR was able to consistently detect maternal cell contamination and mosaic trisomies when the trisomic cell line was present at an adequate level (23% or more). However, QF-PCR was unable to detect chromosomal rearrangements for which the primers were not designed. Conclusion: QF- PCR proved its superior performance as a molecular-based method for autosomal aneuploidy detection concerning both sensitivity and specificity.展开更多
We report a novel C-terminal MECP2 frameshift deletion (1135 1142delCCCGTG CC) in a 19-year-old woman with mental retardation and epilepsy. Preservation of language capabilities, purposeful hand use and sufficient loc...We report a novel C-terminal MECP2 frameshift deletion (1135 1142delCCCGTG CC) in a 19-year-old woman with mental retardation and epilepsy. Preservation of language capabilities, purposeful hand use and sufficient locomotion implied an atypical variant of Rett syndrome (OMIM 312750). Occipito-frontal head circumference was large at birth (36 cm; SDS 1.7) and increased until adulthood (58.5 cm; SDS 2.3). Conclusion: Our observation indicates that head size and head growth are of limited reliability in the diagnosis of MECP2-associated phenotypes.展开更多
文摘We build a model of storage of well-defined positional information in probabilistic sequence patterns. Once a pattern is defined, it is possible to judge the effect of any mutation in it. We show that the frequency of beneficial mutations can be high in general and the same mutation can be either advantageous or deleterious depending on the pattern’s context. The model allows to treat positional information as a physical quantity, formulate its conservation law and to model its continuous evolution in a whole genome, with meaningful applications of basic physical principles such as optimal efficiency and channel capacity. A plausible example of optimal solution analytically describes phase transitions-like behavior. The model shows that, in principle, it is possible to store error-free information on sequences with arbitrary low conservation. The described theoretical framework allows one to approach from novel general perspectives such long-standing paradoxes as excessive junk DNA in large genomes or the corresponding G- and C-values paradoxes. We also expect it to have an effect on a number of fundamental concepts in population genetics including the neutral theory, cost-of-selection dilemma, error catastrophe and others.
基金a DAAD-German Egyptian Research Long-Term Schoolarship(GERLS).
文摘Objectives: The currently available methods for rapid prenatal diagnosis of common chromosomal aneuploidies are either Interphase-Fluorescence in Situ Hybridisation (I-FISH) or Quanti- tative Fluorescent Polymerase Chain Reaction (QF-PCR). QF-PCR represents a rapid, high throughput, cost-effective alternative for Interphase-FISH. The objective of the study was to evaluate the performance of QF-PCR, as a molecular-based technique for the detection of chromosome 21, 18 and 13 copy numbers. Study design: A retrospective cohort of 163 samples referred for screening of common chromosomal aneuploidies was blindly tested for chromosome 21, 18 and 13 copy numbers using QF-PCR and the results were compared with those of conventional cytogenetic analysis. Results: QF-PCR demonstrated optimal sensitivity and specificity (100%) for non mosaic trisomies. QF-PCR was able to consistently detect maternal cell contamination and mosaic trisomies when the trisomic cell line was present at an adequate level (23% or more). However, QF-PCR was unable to detect chromosomal rearrangements for which the primers were not designed. Conclusion: QF- PCR proved its superior performance as a molecular-based method for autosomal aneuploidy detection concerning both sensitivity and specificity.
文摘We report a novel C-terminal MECP2 frameshift deletion (1135 1142delCCCGTG CC) in a 19-year-old woman with mental retardation and epilepsy. Preservation of language capabilities, purposeful hand use and sufficient locomotion implied an atypical variant of Rett syndrome (OMIM 312750). Occipito-frontal head circumference was large at birth (36 cm; SDS 1.7) and increased until adulthood (58.5 cm; SDS 2.3). Conclusion: Our observation indicates that head size and head growth are of limited reliability in the diagnosis of MECP2-associated phenotypes.
