This book has five chapters covering peroxisomal diseases, X-linked immunodeficiencies, genetic mutations affecting human lipoproteins and their receptors and enzymes, genetic aspects of cancer, and Gaucher disease. The chapter on peroxisomes covers their discovery, structure, functions, disorders, etc. The chapter on X-linked immunodeficiencies discusses such diseases as agammaglobulinemia, severe combined immunodeficiency, Wiskott-Aldrich syndrome, animal models, linkage analysis, etc. Apolipoprotein formation, synthesis, gene regulation, proteins, etc. are the main focus of chapter 3. The chapter on cancer covers such topics as oncogene mapping and the molecular characterization of some recessive oncogenes. Gaucher disease is covered from its diagnosis, classification, and prevention, to its organ system involvement and molecular biology.

Advances in Human Genetics

Transferrin (Tf) is the major iron binding protein in vertebrate serum. It shares homologous amino acid sequences with four other proteins: lactotransferrin, ovotransferrin, melanoma antigen p97, and HuBlym-1. Antigen p97 and the Tf receptor genes have been mapped on human chromosome 3. The goal of the study described here was to initiate the characterization of the Tf gene by identifying and characterizing its cDNA and mapping its chromosomal location. Recombinant plasmids containing human cDNA encoding Tf have been isolated by screening an adult human liver library with a mixed oligonucleotide probe. Within the 2.3 kilobase pairs of Tf cDNA analyzed, there is a probable leader sequence encoded by 57 nucleotides followed by 2037 nucleotides that encode the homologous amino and carboxyl domains. During evolution, three areas of the homologous amino and carboxyl domains have been strongly conserved, possibly reflecting functional constraints associated with iron binding. Chromosomal mapping by in situ hybridization and somatic cell hybrid analysis indicate that the Tf gene is located at q21-25 on human chromosome 3, consistent with linkage of the Tf, Tf receptor, and melanoma p97 loci.

https://www.pnas.org/content/pnas/81/9/2752.full.pdf

Human transferrin: cDNA characterization and chromosomal localization

It is estimated that the human haploid genome is composed of 3 × 109 nucleotides and that only 10% of it consists of coding and regulatory sequences.14 If a gene is approximately 104 nucleotides in length, which includes the coding region and the intervening and flanking sequences, this estimate would predict that there are about 3–10 × 104 human genes coding for different protein products. Since gene clustering in humans has become evident (for example, the hemoglobin, immunoglobin, and HLA clusters), these estimated gene products may be grouped in from 3000 to 15,000 clusters.15 Further, based upon genetic and molecular studies of microorganisms, Drosophila, and the mouse, there are perhaps 5 × 104 structural genes estimated in humans,14,106,183 which is in agreement with the number of estimated protein products in the human genome. Mapping the human genome involves partitioning the total number of genes into individual maps representing the 24 different human nuclear chromosomes and linearly ordering them on each chromosome. A similar exercise has mapped the 37 genes encoded in the DNA of the mitochondrial genome.2

Mapping the Human Genome, Cloned Genes, DNA Polymorphisms, and Inherited Disease

Comparative maps for mice and humans have been exceptionally important for predicting linkages, for identifying homologous mutations and disease loci, and for studying genome organization and evolution. This report summarizes the status of this comparative map. We provided a listing of homologous genes and anonymous loci that have been mapped in mice and humans together with references documenting homology and the chromosomal and linkage assignments (Table 1). We used a matrix to help readers find con-

/pdf/comparative-map-for-mice-and-humans-fygmq2ux5o.pdf

Comparative map for mice and humans.

The human gene for interleukin 2 (IL2)was assigned to chromosome 4 using human-mouse somatic cell hybrids and Southern filter hybridization of cell hybrid DNA. To identify IL2,a recombinant DNA probe (pIL2-50A) was used which contained a human interleukin 2 cDNA insert which hybridized to a 3.5-kb fragment in human DNA when cleaved with the restriction enzyme EcoRL.

Interleukin 2 (IL2) is assigned to human chromosome 4.

Conserved linkage groups have been found on the X and autosomal chromosomes in several mammalian species. The identification of conserved chromosomal regions has potential for predicting gene location in mammals, particularly in humans. The genes for human aminoacylase-1 (ACY1, N-acylamino acid aminohydrolase, E.C.3.5.1.14), an enzyme in amino acid metabolism, and beta-galactosidase-A (GLB1, E.C.3.2.1.23), deficient in GM1-gangliosidosis, have been assigned to human chromosome 3. Using human-mouse somatic cell hybrids segregating translocations of human chromosome 3, expression of both ACY1 and GLB1 correlated with the presence of the p21 leads to q21 region of chromosome 3. In a previous study, assignment of these genes to mouse chromosome 9 used mouse-Chinese hamster somatic cell hybrids, eliminating mouse chromosomes. To approximate the size of the conserved region in the mouse, experiments were performed with recombinant inbred mouse strains. An electrophoretic variant of ACY-1 in mouse strains was used to map the Acy-1 gene 10.7 map U from the beta-galactosidase locus. These data suggest that there is a region of homology within the p21 leads to q21 region of human chromosome 3 and a segment of mouse chromosome 9. Since the mouse transferrin gene (Trf) is closely linked to the aminoacylase and beta-galactosidase loci, we predict that the human transferrin (TF) gene is on chromosome 3.

Mapping of aminoacylase-1 and beta-galactosidase-A to homologous regions of human chromosome 3 and mouse chromosome 9 suggests location of additional genes.

R W Elliott

Papers

Mapping of aminoacylase-1 and beta-galactosidase-A to homologous regions of human chromosome 3 and mouse chromosome 9 suggests location of additional genes.