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Biomedical subjects

P J McAlpine

Publications and source records attributed to P J McAlpine.

At least 19 recordsLinked to original sources

Complementation by two non-homologous recombinant chromosomes 3.

The first example known to us of complementation by two non-homologous chromosomes 3 is present in the karyotype of a phenotypically normal brother of an inv(3)(p25q21) carrier. The normal chromosomes 3 are replaced by two complementary recombinant chromosomes 3. The longer recombinant duplicates 3q21-qter and is deficient for 3p25-pter. It is identical to the recombinant inherited by infants born with multiple congenital anomalies to inv(3)(p25q21) carriers. The shorter recombinant duplicates 3p25-pter and is deficient for 3q21-qter. This recombinant has previously been observed only in prometaphase spreads from sperm of an inv(3) carrier from the same kindred. Theoretically it is possible for the carrier of these complementary recombinant chromosomes 3 to produce sperm carrying either a normal 3, or the inversion 3, which could then fertilize an egg carrying a normal 3 followed by normal fetal development. However, the spouse of our propositus reported one first trimester spontaneous abortion, followed by no recognized pregnancy over the next 12 years of marriage.

Chromosome Inversion

The cloned butyrylcholinesterase (BCHE) gene maps to a single chromosome site, 3q26.

Human tissues have two distinct cholinesterase activities: acetylcholinesterase and butyrylcholinesterase. Acetylcholinesterase functions in the transmission of nerve impulses, whereas the physiological function of butyryl-cholinesterase remains unknown. An atypical form of butyrylcholinesterase or the absence of its activity leads to prolonged apnea following administration of the muscle relaxant suxamethonium. Inheritance of these butyrylcholinesterase variants is consistent with the enzyme activity being encoded in a single autosomal locus, BCHE (formerly CHE1 and E1), which has been assigned to chromosome 3. Previous in situ hybridization of a BCHE cDNA probe gave evidence of homologous sequences at 3q26 and 16q11-q23, raising the possibility of more than one locus coding for butyrylcholinesterase [H. Soreq, R. Zamir, D. Zevin-Sonkin, and H. Zakut (1987) Hum. Genet. 77: 325-328]. Using a different cDNA probe hybridized in situ to 46,XX,inv(3)(p25q21) metaphase chromosomes, we report here the localization of BCHE to a single autosomal location: 3q26.

Autoradiography

The low-incidence red cell antigen Wra: genetic studies.

Studies of 91 individuals in three families allowed a genetic-linkage analysis of the gene governing the production of the low-incidence red cell antigen Wra and provided evidence that Wra is not a member of the Scianna, Landsteiner-Wiener, Chido/Rodgers, or XK blood group systems, and that the "WR" locus is excluded from autosomal sites or regions 1p34-p22.1, 1p21-q23, 1q32, 2p25, 3q21, 4q28-q32, 6p24-q12, 9q34.1-q34.2, 13q14.1-q14.2, 14q24.3-q32.1, 14q32.33, 16p13, 16q22.1, and 21q21-q22.1. "WR" is also excluded from within specified genetic distances of chromosomes 8 (GPT), 18 (JK), 19 (C3), 20 (ADA), and 22 (P1) loci, which brings its exclusion to approximately 10 percent (320cM) of the total genetic map of the genome. The possibility that "WR" is pseudoautosomal is deemed to be highly unlikely.

Blood Group Antigens

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Chromosome Mapping

Localization of a locus for Charcot-Marie-Tooth neuropathy type Ia (CMT1A) to chromosome 17.

Phenotypic data for 71 genetic markers for members of five Caucasian kindreds were tested for linkage with the autosomal dominant mutations causing Charcot-Marie-Tooth (hereditary motor sensory) neuropathy type I, characterized by markedly reduced nerve conduction velocities. Lod score analysis gave no evidence of linkage to the closely linked chromosome 1 loci SPTA1-FY-F5-AT3 and APOA2. In contrast, these mutations were found to map closely (zeta = 10.828, theta = 0.0) to D17S58, an anonymous segment of DNA from 17p11.2-p11.1, and thus define the CMT1A locus. Segregation information data for an inferred recombinant offspring indicated that the CMT1A locus is probably proximal to MYH2, the locus encoding adult skeletal muscle myosin heavy polypeptide 2, which maps to 17p13. Analysis of the lod scores on a per kindred basis gave no evidence of genetic heterogeneity.

Charcot-Marie-Tooth Disease

Evidence that SE is distal to LU on chromosome 19q.

Analysis of a family informative for chromosome 19 loci establishes that the Lutheran blood group locus (LU) lies between the third component of human complement (C3) and the secretor loci (SE). Previously published lod scores for C3:LU are increased from 2.94 to 3.80. The linkage relationships (zeta and theta) between C3, LU, and SE are examined, and the proposed order and approximate genetic distances are determined to be: pter--C3-10.6cM-cen-7.4cM-LU-9cM-SE--qter.

Chromosomes, Human, Pair 19

Analysis for linkage between F13A and three chromosome 6 marker loci: evidence for 6pter:F13A:HLA:GLO1:cen gene order.

The results of the present study provide independent support for F13A:HLA linkage and refine the F13A:HLA and F13A:GLO1 linkage relationships. Analysis of the corresponding recombination fractions for the total paternal F13A:HLA and F13A:GLO1 peak lod scores (z) indicates a locus order of 6pter:F13A:HLA:GLO1:cen. Lod scores between F13A and PLG, a locus recently assigned to chromosome 6, exclude close linkage between these loci.

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