Biomedical subjects
Publications and source records attributed to Y Nakagome.
Twenty-four novel cosmid clones were cloned and mapped on the human Y chromosome using a panel consisting of DNA from seven individuals each having a different segment of the Y chromosome. Eight were assigned to the short arm, 15 to the long arm and 1 to the both short and long arms.
Results of DNA study on two patients of gonadal dysgenesis with a 45,X/46,X,Ynf (non-fluorescent Y chromosome) karyotype are described. In one patient who developed gonadoblastoma, all 12 loci on the non-fluorescent part of Yq were detected. Another patient did not have gonadoblastoma at 20 years, and only the proximal 6 loci out of 12 were detected.
Three probes each detecting a locus on the proximal long arm of the Y chromosome were partially sequenced. Thus, 3 sets of novel primers were developed which enable PCR detection of these 3 loci. Five previously reported primer sets, 3 on the short arm and each one on the centromere and the distal long arm, were mapped along with the novel three using a mapping panel consisted of 8 patients each with different structural abnormality of the Y chromosome. Now, PCR detection of these 8 loci covering an entire length of the Y chromosome has become possible enabling rapid screening of patients with Y chromosome aberrations.
Sex determination by polymerase chain reaction (PCR) analysis of the X-Y homologous amelogenin gene is highly reliable since the detection of an X-specific amplified fragment validates the procedure. Previously, we reported that 250 ng of template DNA are required for sex determination by this method. We report here a refinement of the technique to include dual PCR. Dual PCR using two sets of primers results in the detection of X- and Y-specific amplified fragments from as little as 0.005 ng of template DNA. This is a powerful technique for the analysis of trace forensic samples and its application is discussed.
Two XX male patients were examined for the presence of 25 Y-specific loci using Southern blot analysis and polymerase chain reaction techniques. They were phenotypically normal male patients, although 1 had bilateral undescended testes and 1 had hypoplastic testes. The former patient had 10 of 11 loci on the short arm, while the latter lacked any of the 25 Y-specific loci. These findings may suggest the existence of a non-Y gene that is controlled by the testis-determining factor on the short arm of the Y chromosome and has a role in the testis formation in man.
The probe 47z detects DNA polymorphisms on both the X and Y chromosomes. Blood samples were collected from Korean, Chinese, Jewish, Caucasian and Negro populations and polymorphisms of both loci were compared with findings previously reported in Japanese. Both Y1 and Y2 alleles were detected in Japanese and Koreans. However, only the Y1 allele was detected in each of the other populations. Although, both X1 and X2 alleles were detected in all examined populations, the frequency of the X2 allele was very low among Negroes.
A bovine XY female in Holstein-Friesian heifer, which appeared as female with uterus and ovaries but did not show the estrus until 23 months old after the birth, was cytogenetically and molecularbiologically examined. As results of chromosome analysis, leucocyte and fibroblasts from skin, spleen and kidney examined had only metaphase plates with 60, XY. From these results and the clinical characteristics, this case was clearly diagnosed as a pure XY female. It was ascertained that the two genes, ZFY and AMG gene which located on the short arm of the Y chromosome (Yp) were detected in normal bulls and a XY female, but were not detected in normal cow, mother cow and half-sib heifer by Southern blotting.
The application of variable number of tandem repeat (VNTR) markers to the determination of twin zygosity was investigated. In the first case, which was performed with the use of six VNTR markers, the probability of monozygosity, calculated from Essen-Möller's formula II, was 0.99972. In the other three cases in which four VNTR markers were analyzed, the probabilities were 0.98251-0.99557. These results suggest that VNTR markers are useful for determination of twin zygosity.
An XX true hermaphrodite was examined for the presence of Y-specific sequences using Southern-blotting and polymerase chain reaction (PCR) techniques. Of 25 loci examined, only two, the proximal border of the pseudoautosomal region (PABY) and the sex determining region of the Y chromosome (SRY), were detected. A crossing over event in paternal meiosis, proximal to the SRY locus but distal to the zinc finger protein (ZFY) locus, presumably transferred to two loci to the X chromosome.
A dual polymerase chain reaction (PCR) technique is developed which enables the detection of one part male DNA in 25,000 parts female DNA. The technique amplifies a part of the X-Y homologous amelogenin gene in which the Y counterpart has a 189 bp deletion within one of the introns. This deletion has made it possible to identify individual X and Y counterparts based on the difference in size between them. None of the 18 pregnant women studied showed a positive Y-signal although eight of them bear male fetuses excluding the presence of fetal cells at one in 25,000 maternal cells. The results presented here show that a sensitivity of greater than one in 25,000 is required for detection of fetal genetic disease using maternal peripheral blood.
A method of sex identification using the polymerase chain reaction technique is described. Using a pair of nucleotide primers from an X-Y homologous region, both the X and the Y sequences can be amplified simultaneously, and more importantly, they result in fragments of different lengths. The success of the procedure is therefore monitored by the presence of a X-specific band while sex is identified by the presence or absence of a Y-specific band.
A Japanese boy with genital malformation and mixed gonadal dysgenesis is described. The karyotype appeared to be 46,X t(15;Y)(p13;q11). A comparison of the Q-positive segment on der(15) with that of the paternal Y chromosome revealed, however, the loss of over half of the Q-positive segment from the paternal Y during t(15;Y) translocation. The father had an unusually long Y chromosome that corresponded to a chromosome 18. DNA analysis further revealed a deletion of the non-fluorescent part of the long arm of the Y chromosome spanning interval 5-6.
A female patient with unilateral gonadal dysgenesis was a mosaic for three cell lines, 45,X/46,X, + marI/46,X, + marII, including two different marker chromosomes. DNA analysis using 17 Y-specific DNA probes revealed that each marker consists of different segments of the Y chromosome.
Amelogenesis imperfecta is characterized by the defective formation of tooth enamel. Here we present evidence that the X-linked form of this disorder (AIH1) is caused by a structural alteration in one of the predominant proteins in enamel, amelogenin. Southern blot analysis revealed a deletion extending over 5 kb of the amelogenin gene in males with the hypomineralization form of the AIH1. Carrier females were heterozygous for the molecular defect. The deletion appears to include at least two exons of the amelogenin gene and the extent of the deletion was verified by PCR analysis. The mutation was shown to segregate with the disease among 15 analyzed individuals belonging to the same kindred. Our results link a defect in the amelogenin gene to the abnormal formation of enamel. We thus conclude that the amelogenin protein has a role in biomineralization of tooth enamel.
Results of cloning and sequencing of genomic sequences from the X and Y chromosomes that encode the tooth enamel gene amelogenin (both AMG and AMGL) are described. Three exons are defined on both the X and Y sequences. The nucleotide sequences reported here offer basic information for investigating human amelogenin.
A hypospadiac boy with a hypoplastic penis and an apparent 46,XX karyotype in blood and testis cultures is described. Exploratory laparotomy and bilateral gonadal biopsy revealed the presence of 2 testes in the right and 1 in the left hemiscrotum, each of which only showed hypoplastic testicular tissues histologically. Uncultured testis smears showed Y chromatin in approximately 20% of the cells. Also, the Southern blot and polymerase chain reaction analyses detected a weak but distinct signal of Y chromosome-derived deoxyribonucleic acid sequences in the perineal skin but not in the blood lymphocytes. The results indicated that the boy had a small proportion of Y chromosome-containing cells in the form of mosaicism in limited tissues, such as the testes and perineal skin. This finding may have implications in the genesis of testes in some cases of XX patients, and true hermaphrodites or male pseudohermaphrodites with an apparent 46,XX karyotype. To our knowledge, this appears to be the first case of polyorchidism with an identified chromosome abnormality.
An average-sized human Y chromosome contains about 3,000 copies of the repeating DNA family DYZ1. A major repeating unit of the family, pHY10, has been cloned and an entire 3,564-bp sequence has already been determined by Nakahori et al. (1986). In the present study, pHY10 was divided into six consecutive segments, A to F, which were independently amplified by the PCR technique to see if they were strictly male-specific. pHY10 appears to consist of segments of various male-specificity. The B segment was apparently male-specific; however, the use of additional techniques (Southern-blot analysis or second PCR amplification in combination with the standard PCR) revealed homologous sequences in some females. None of the six segments of pHY10 may be male-specific in a strict sense. Different segments appear to be conserved during evolution to different extents. The 323-bp E segment appears to be the least conserved and to be responsible for the generation of most variations within the DYZ1 family.