Lmna Mutations and HGPS
Collins and his team of researchers decided to screen 23 affected individuals for mutations of the Lmna gene. They chose the Lmna gene due to its involvement in a wide spectrum of heritable disorders including Emery-Dreifuss muscular dystrophy, familial partial lipodystrophy, limb girdle muscular dystrophy, and Charcot-Marie-Tooth disease (“Lmna”). The decision to screen the Lmna gene definitely paid off, as three different mutations were discovered. The mutations encompassed the substitution of just one base, and included the following: G608G (GGC > GGT), G608S (GGC > AGC), and E145K (GAG > AAG) (Pollex RL et. al. 2004). In each case, the affected individual carried only one mutation, and were heterozygous for …show more content…
The sequence tracers form the HGPS patients include the two base substitutions that occurred on codon 608, including the G608G (GGC > GGT) and G608S (GGC > ACG) respectively. Part b of the diagram suggests that both of the observed HGPS mutations might activate a cryptic splice site in exon 11. Figure c in the diagram shows the results of testing this hypothesis. It is a demonstration of the abnormal splice product using reverse-transcription polymerase chain reaction, a technique used in genetic studies that allows the detection and quantification of mRNA. This method shows whether or not a specific gene is being expressed in a given sample. While the RNA from the unaffected individuals produces the expected product, the diagram shows an abnormal product of 489 bp in the samples that were affected by HGPS due to the activation of the cryptic splice site. A western blot, a procedure used to identify specific amino acid sequences in proteins, was performed (section d) using an antibody against lamin A/C. This was conducted to determine whether the mutant messenger RNA was actually translated into a protein. The figure shows an additional band present in the four lanes that corresponded to samples from HGPS cases, proving that the mRNA was in fact translated into a protein (Eriksson, Maria et. al. …show more content…
Nuclear lamins have been identified as the major components of the nuclear lamina, and are also present in the nuclear interior as well as in lamin associated proteins (Gruenbaum Y, et. al. 2003). The nuclear lamina is a highly complex structure that encompasses many protein interactions with lamins and compound interactions between these proteins and chromatin associated proteins. The nuclear lamina plays a crucial role in most nuclear activities as well as being a critical component of maintaining nuclear structure and shape. It is involved in DNA replication, RNA transcription, nuclear and chromatin organization, cell cycle regulation, and cell development and differentiation (Gruenbaum Y et. al.
Collins and his team of researchers decided to screen 23 affected individuals for mutations of the Lmna gene. They chose the Lmna gene due to its involvement in a wide spectrum of heritable disorders including Emery-Dreifuss muscular dystrophy, familial partial lipodystrophy, limb girdle muscular dystrophy, and Charcot-Marie-Tooth disease (“Lmna”). The decision to screen the Lmna gene definitely paid off, as three different mutations were discovered. The mutations encompassed the substitution of just one base, and included the following: G608G (GGC > GGT), G608S (GGC > AGC), and E145K (GAG > AAG) (Pollex RL et. al. 2004). In each case, the affected individual carried only one mutation, and were heterozygous for …show more content…
The sequence tracers form the HGPS patients include the two base substitutions that occurred on codon 608, including the G608G (GGC > GGT) and G608S (GGC > ACG) respectively. Part b of the diagram suggests that both of the observed HGPS mutations might activate a cryptic splice site in exon 11. Figure c in the diagram shows the results of testing this hypothesis. It is a demonstration of the abnormal splice product using reverse-transcription polymerase chain reaction, a technique used in genetic studies that allows the detection and quantification of mRNA. This method shows whether or not a specific gene is being expressed in a given sample. While the RNA from the unaffected individuals produces the expected product, the diagram shows an abnormal product of 489 bp in the samples that were affected by HGPS due to the activation of the cryptic splice site. A western blot, a procedure used to identify specific amino acid sequences in proteins, was performed (section d) using an antibody against lamin A/C. This was conducted to determine whether the mutant messenger RNA was actually translated into a protein. The figure shows an additional band present in the four lanes that corresponded to samples from HGPS cases, proving that the mRNA was in fact translated into a protein (Eriksson, Maria et. al. …show more content…
Nuclear lamins have been identified as the major components of the nuclear lamina, and are also present in the nuclear interior as well as in lamin associated proteins (Gruenbaum Y, et. al. 2003). The nuclear lamina is a highly complex structure that encompasses many protein interactions with lamins and compound interactions between these proteins and chromatin associated proteins. The nuclear lamina plays a crucial role in most nuclear activities as well as being a critical component of maintaining nuclear structure and shape. It is involved in DNA replication, RNA transcription, nuclear and chromatin organization, cell cycle regulation, and cell development and differentiation (Gruenbaum Y et. al.