Congenital nephrotic syndrome of the Finnish type (NPHS1) is an autosomal-recessive disorder, characterized by massive proteinuria in utero and nephrosis at birth. In this study, the 150 kb critical region of NPHS1 was sequenced, revealing the presence of at least 11 genes, the structures of 5 of which were determined. Four different mutations segregating with the disease were found in one of the genes in NPHS1 patients. The NPHS1 gene product, termed nephrin, is a 1241-residue putative transmembrane protein of the immunoglobulin family of cell adhesion molecules, which by Northern and in situ hybridization was shown to be specifically expressed in renal glomeruli. The results demonstrate a crucial role for this protein in the development or function of the kidney filtration barrier.

Congenital nephrotic syndrome of the Finnish type (NPHS1) is an autosomal recessive disorder that is caused by mutations in the recently discovered nephrin gene, NPHS1 (AF035835). The disease, which belongs to the Finnish disease heritage, exists predominantly in Finland, but many cases have been observed elsewhere in Europe and North America. The nephrin gene consists of 29 exons spanning 26 kb in the chromosomal region 19q13.1. In the present study, the genomic structure of the nephrin gene was analyzed, and 35 NPHS1 patients were screened for the presence of mutations in the gene. A total of 32 novel mutations, including deletions; insertions; nonsense, missense, and splicing mutations; and two common polymorphisms were found. Only two Swedish and four Finnish patients had the typical Finnish mutations: a 2-bp deletion in exon 2 (Finmajor) or a nonsense mutation in exon 26 (Finminor). In seven cases, no mutations were found in the coding region of the NPHS1 gene or in the immediate 5'-flanking region. These patients may have mutations elsewhere in the promoter, in intron areas, or in a gene encoding another protein that interacts with nephrin.

Chromosome 19 has the highest gene density of all human chromosomes, more than double the genome-wide average. The large clustered gene families, corresponding high G1C content, CpG islands and density of repetitive DNA indicate a chromosome rich in biological and evolutionary significance. Here we describe 55.8 million base pairs of highly accurate finished sequence representing 99.9% of the euchromatin portion of the chromosome. Manual curation of gene loci reveals 1,461 protein-coding genes and 321 pseudogenes. Among these are genes directly implicated in mendelian disorders, including familial hypercholesterolaemia and insulin-resistant diabetes. Nearly one-quarter of these genes belong to tandemly arranged families, encompassing more than 25% of the chromosome. Comparative analyses show a fascinating picture of conservation and divergence, revealing large blocks of gene orthology with rodents, scattered regions with more recent gene family expansions and deletions, and segments of coding and non-coding conservation with the distant fish species Takifugu.

We investigated the organization, architecture, and evolution of the largest cluster (∼4 Mb) of Krüppel-associated box zinc finger (KRAB-ZNF) genes located in cytogenetic band interval 19p12. A highly integrated physical map (∼700 kb) of overlapping cosmid and BAC clones was developed between genetic STS markers D19S454 and D19S269. Using ZNF91 exon-specific probes to interrogate a detailed EcoRI restriction map of the region, ZNF genes were found to be distributed in a head-to-tail fashion throughout the region with an average density of one ZNF duplicon every 150-180 kb of genomic distance. Sequence analysis of 208,967 bp of this region indicated the presence of two putative ZNF genes: one consisting of a novel member of this gene family (ZNF208) expressed ubiquitously in all tissues examined and the other representing a nonprocessed pseudogene (ZNF209), located 450 kb proximal to ZNF208. Large blocks of (∼25-kb) inverted ␤-satellite repeats with a remarkably symmetrical higher order repeat structure were found to bracket the functional ZNF gene. Hybridization analysis using the ␤-satellite repeat as a probe indicates that ␤-satellite interspersion between ZNF gene cassettes is a general property for 1.5 Mb of the ZNF gene cluster in 19p12. Both molecular clock data as well as a retroposon-mapping molecular fossil approach indicate that this ZNF cluster arose early during primate evolution (∼50 million years ago). We propose an evolutionary model in which heteromorphic pericentromeric repeat structures such as the ␤ satellites have been coopted to accommodate rapid expansion of a large gene family over a short period of evolutionary time.[The sequence data described in this paper have been submitted to GenBank under accession nos. AC003973 and AC004004.] Zinc finger (ZNF) genes represent one of the largest gene families in the human genome with an estimated 500-600 members (Hoovers et al. 1992;Becker et al. 1995;Klug and Schwabe 1995). Although the specific function of the majority of ZNF genes remains largely unknown, as a class they are believed to encode transcriptional regulators that in a few instances have been shown to play critical roles in cellular and developmental differentiation processes (Pieler and Bellefroid 1994). ZNF proteins have been implicated in many diverse eukaryotic developmental processes, such as segment pattern formation in the Drosophila embryo (Rosenberg et al. 1986); cellular proliferation in the cerebellar hindbrain of the mouse (Wilkinson et al. 1989); and hematopoietic differentiation among human myeloid precursor cells (Hromas et al. 1991). DNA binding of the encoded proteins is typically mediated by a ZNF motif that consists either of two cysteines and two histidines (Krüppel family or C 2 /H 2 type) or four cysteines alone (steroid receptor or C 2 / C 2 type). The conserved cysteines and/or histidines form a tetrahedral complex around a zinc metal ion, generating a folded loop or ''finger'' of 30 amino acids that is capable of making contact with DNA (Miller et al. 1985)...