1/2. A missense mutation in the proteolipid protein gene responsible for pelizaeus-merzbacher disease in a Japanese family.We investigated the proteolipid protein (PLP) gene of two boys in a Japanese family with pelizaeus-merzbacher disease (PMD), an X-linked neurologic disorder characterized by dysmyelination in the central nervous system (CNS). The patients showed similar clinical signs from birth and autopsy on the elder brother confirmed a connatal type of PMD. Direct sequencing of the PLP gene and PLP mRNAs from the brain of the PMD patient revealed a G to T transition in exon V of the PLP gene, which leads to a glycine to cysteine substitution at residue 220. Allele-specific oligonucleotide hybridization revealed that this mutation was also present in his brother, but was absent in 100 X chromosomes of normal Japanese individuals. Northern blot analysis showed that the mRNA levels of PLP and myelin basic protein, two major myelin proteins produced by oligodendrocytes, were much reduced in the PMD brain, hence, there was a specific loss of oligodendrocytes. It seems likely that the substitution is responsible for PMD (connatal type) in this particular family and causes oligodendrocytes death in the CNS.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
2/2. sex determination of human embryos using the polymerase chain reaction and confirmation by fluorescence in situ hybridization.OBJECTIVE: To use fluorescence in situ hybridization to corroborate the polymerase chain reaction (PCR) preimplantation diagnosis of human embryos in three couples carrying a chromosome X-linked disease. SETTING: Clinical and research IVF laboratories. patients: Individuals undergoing preimplantation diagnosis. RESULTS: Four ETs were performed in couples undergoing preimplantation diagnosis by multiplex PCR or fluorescence in situ hybridization, resulting in the birth of two normal female twins. The result of another is pending. A total of 22 embryos were analyzed by PCR. Embryos that were diagnosed as being at risk of carrying the genetic abnormality (n = 8), embryos that failed diagnosis (n = 4), and genetically normal embryos that arrested development (n = 4) were further analyzed by fluorescence in situ hybridization. The sex of all 16 embryos was determined and confirmed the previous 12 preimplantation diagnoses by multiplex PCR. In addition, fluorescence in situ hybridization analysis allowed the detection of two aneuploid embryos, one XO and one XXY, previously diagnosed by PCR as a normal female and male. Two mosaics were also detected. CONCLUSION: polymerase chain reaction and fluorescence in situ hybridization are possible for preimplantation sex determination in cases of genetic sex-linked disease. fluorescence in situ hybridization, however, supplies additional information about sex chromosome aneuploidy and is not susceptible to contamination or misdiagnosis of monosomy X.- - - - - - - - - - ranking = 10keywords = hybridization (Clic here for more details about this article) |