14-3-3 epsilon has no homology to LIS1 and lies telomeric to it on chromosome 17p13.3 outside the Miller-Dieker syndrome chromosome region.

Previously, we isolated several cDNA clones of the LIS1 gene implicated in Miller-Dieker syndrome. Analysis of the 5' end of one of the clones (8-1), which was originally thought to represent the 5' end of LIS1, indicates a striking similarity to mouse 14-3-3 epsilon. We have isolated a full-length cDNA of human 14-3-3 epsilon, for which sequence analysis reveals a strong nucleotide conservation with mouse 14-3-3 epsilon in both translated and untranslated regions (UTRs).

Fine mapping of the cystinosis gene using an integrated genetic and physical map of a region within human chromosome band 17p13.

The cystinosis gene has been reported to reside in a 3.1 cM region of chromosome 17p13 flanked by markers D17S1828 and D17S1798. We created a yeast artificial chromosome (YAC) contig between these markers and report here an integrated genetic and physical map which will aid in the identification of other genes in this area.

X-linked malformations of neuronal migration.

Malformations of neuronal migration such as lissencephaly (agyria-pachygyria spectrum) are well-known causes of mental retardation and epilepsy that are often genetic. For example, isolated lissencephaly sequence and Miller-Dieker syndrome are caused by deletions involving a lissencephaly gene in chromosome 17p13.3, while many other malformation syndromes have autosomal recessive inheritance.

Multicolor spectral karyotyping of human chromosomes.

The simultaneous and unequivocal discernment of all human chromosomes in different colors would be of significant clinical and biologic importance. Whole-genome scanning by spectral karyotyping allowed instantaneous visualization of defined emission spectra for each human chromosome after fluorescence in situ hybridization. By means of computer separation (classification) of spectra, spectrally overlapping chromosome-specific DNA probes could be resolved, and all human chromosomes were simultaneously identified.

A YAC contig of the human CC chemokine genes clustered on chromosome 17q11.2.

CC chemokines are cytokines that attract and activate leukocytes. The human genes for the CC chemokines are clustered on chromosome 17. To elucidate the genomic organization of the CC chemokine genes, we constructed a YAC contig comprising 34 clones.

Isolation of the human chromosome 22q telomere and its application to detection of cryptic chromosomal abnormalities.

A number of human telomeres have been successfully cloned using a modified yeast artificial chromosome (YAC) vector (half-YAC) cloning strategy, but to date, human chromosome 22q has not been identified by this approach. We used an alternative approach of genomic walking, starting from a subtelomeric sequence, Tel-Bam3.4.

Unilateral cleft lip in a boy with Angelman syndrome.

We report on a mentally retarded boy with epileptic seizures, microcephaly, ataxia, and developmental delay. His clinical features were consistent with Angelman syndrome. Fluorescent in situ hybridization and DNA analysis showed a deletion of chromosome 15 q11-13 and thus confirmed the diagnosis.

Prenatal diagnosis of uniparental disomy 15 following trisomy 15 mosaicism.

Maternal uniparental disomy 15 (UPD15), responsible for approximately 25 per cent of Prader-Willi syndrome cases, is usually caused by maternal meiosis I non-disjunction associated with advanced maternal age. These cases may initially be detected as mosaic trisomy 15 during routine prenatal diagnostic studies. In such cases, PCR (polymerase chain reaction) microsatellite analysis of uncultured cells makes prospective prenatal diagnosis for UPD15 possible with results available in 2-4 days.

Miller-Dieker syndrome resulting from rearrangement of a familial chromosome 17 inversion detected by fluorescence in situ hybridisation.

We report a case of Miller-Dieker syndrome (MDS) owing to an unbalanced rearrangement of a familial pericentric inversion of chromosome 17 (inv(17) (p13.3q25.1)).

LIS2, gene and pseudogene, homologous to LIS1 (lissencephaly 1), located on the short and long arms of chromosome 2.

We report here the isolation of a novel cDNA, designated LIS2, that maps to chromosome 2p11.2 by in situ hybridization and demonstrates extremely high sequence similarity to the recently identified LIS1 gene involved in Miller-Dieker lissencephaly at 17p13.3.

Detection of a subtle rearrangement of chromosome 22 using molecular techniques.

Conventional cytogenetics is a useful clinical tool that has a lower limit of sensitivity of 2-5 Mb for detection of duplications or deletions. Because the threshold of clinically significant aneusomy is below this range, there is a need for approaches to improve the sensitivity of the detection of aneusomy. We have implemented a system of screening for subtle unbalanced translocations in children with multiple congenital anomalies of unknown cause.

A new dinucleotide repeat polymorphism at the telomere of chromosome 21q reveals a significant difference between male and female rates of recombination.

We have used a half-YAC containing the human chromosome 21 long-arm telomere to clone, map, and characterize a new dinucleotide repeat polymorphism (D21S1575) close to 21qter. This marker is < 120 kb from the telomeric (TTAGGG)n sequences and is the most distal highly polymorphic marker on chromosome 21q. This marker has a heterozygosity of 71% because of a variable (TA)n repeat embedded within a long interspersed element (LINE) element.

Molecular characterization of two proximal deletion breakpoint regions in both Prader-Willi and Angelman syndrome patients.

Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are distinct mental retardation syndromes caused by paternal and maternal deficiencies, respectively, in chromosome 15q11-q13. Approximately 70% of these patients have a large deletion of approximately 4 Mb extending from D15S9 (ML34) through D15S12 (IR10). To further characterize the deletion breakpoints proximal to D15S9, three new polymorphic microsatellite markers were developed that showed observed heterozygosities of 60%-87%.

Replication banding and molecular studies of a mosaic, unbalanced dic(X;15)(Xpter-->Xq26.1::15p11-->15qter).

We present a patient with a chromosomal mosaicism involving the X chromosome. One cell line is 45,X and the other has a de novo paternally derived dicentric X;15 translocation. Her karyotype is therefore 45,X/45,X,dic(X;15)(Xpter-->Xq26.

Tissue-specific and allele-specific replication timing control in the imprinted human Prader-Willi syndrome region.

To examine the relationship between replication timing and differential gene transcription in tissue-specific and imprinted settings we have studied the replication timing properties of the human Prader-Willi syndrome (PWS) region on human chromosome 15q11-13. Interphase fluorescence in situ hybridization with an overlapping series of cosmid clones was used to map a PWS replication timing domain to a 500- to 650-kb region that includes the SNRPN gene. This PWS domain replicates late in lymphocytes but predominantly early in neuroblasts, with replication asynchrony observed in both tissues, and appears to colocalize with a genetically imprinted transcription domain showing prominent expression in the brain.

Spatial organization of ABR and CRK genes on human chromosome band 17p13.3.

Deletion of part or all of chromosome 17p is among the most frequent chromosome abnormalities in human cancer. We show that the CRK and ABR genes are close to a marker on chromosome 17p13.3, D17S34, which is frequently deleted in different tumours, and demonstrate that CRK is centromeric to ABR.

Summary of the 1993 ASHG ancillary meeting "recent research on chromosome 4p syndromes and genes".

The following is a summary of presentations given during an ancillary meeting to the 1993 American Society of Human Genetics Meeting in New Orleans, LA. This ancillary meeting, entitled "Recent Research on Chromosome 4p Syndromes and Genes," reviewed the history of the Wolf-Hirschhorn syndrome (WHS), the natural history of patients with WHS, and the smallest region of deletion associated with the WHS. The proximal 4p deletion syndrome and the duplication 4p syndrome were also described and advice was offered regarding detection of chromosome 4p deletions, duplications, and rearrangements.

Uniparental disomy in humans: development of an imprinting map and its implications for prenatal diagnosis.

Uniparental disomy (UPD) in humans is caused primarily by meiotic nondisjunction events, followed by trisomy or monosomy 'rescue'. The majority of cases appear to be associated with advanced maternal age, and may be initially detected as mosaic trisomies during routine prenatal diagnosis by chorionic villus sampling or amniocentesis. In addition, structural abnormalities including Robertsonian translocations, reciprocal translocations and supernumerary marker chromosomes appear to be associated with an increased risk of UPD.

A variety of genetic mechanisms are associated with the Prader-Willi syndrome.

An extensive set of chromosome 15 DNA polymorphisms and densitometric analysis with four markers mapping to the Prader-Willi chromosome region (PWCR) of chromosome 15 have been used to characterize a cohort of 30 subjects with classical Prader-Willi syndrome (PWS). Molecular analysis enabled the classification of the PWS subjects into four groups: (A) 18 subjects (60%) had deletions of paternal 15q11-13 involving a common set of DNA markers. Two subjects had differently sized deletions, one larger and one smaller than the other cases.

Deletions of a differentially methylated CpG island at the SNRPN gene define a putative imprinting control region.

To determine the molecular basis of Prader-Willi syndrome (PWS) and Angelman syndrome (AS), we have isolated new transcripts from chromosome 15q11-q13. Two novel transcripts located within 300 kilobases telomeric to the small nuclear ribonucleoprotein-associated polypeptide N gene (SNRPN) were paternally expressed in cultured cells, along with SNRPN, defining a large imprinted transcriptional domain. In three PWS patients (two sibs), small deletions remove a differentially methylated CpG island containing a newly described 5' exon alpha of SNRPN, and cause loss of expression for the three imprinted transcripts and altered methylation over hundreds of kilobases.

Isochromosome 15q of maternal origin in two Prader-Willi syndrome patients previously diagnosed erroneously as cytogenetic deletions.

Since our previous report on two Prader-Willi syndrome (PWS) patients with t(15q;15q) (Niikawa and Ishikiriyama; Hum Genet 69:22-27, 1985) was erroneous, we report here new data and a corrected interpretation. Reexamination of the parental origin of their t(15q;15q) using polymorphic DNA markers that are mapped to various regions of 15q documented no molecular deletions at the 15q11-q13 region in either patient. Both patients were homozygous at all loci examined and their haplotypes on 15q coincided with one of those in their respective mothers.

Detailed analysis of loss of heterozygosity on chromosome band 17p13 in breast carcinoma on the basis of a high-resolution physical map with 29 markers.

We have constructed a physical map of chromosome band 17p13, using 29 markers that had been localized to 17p13 by means of fluorescence in situ hybridization (FISH) and analysis by pulsed-field gel electrophoresis (PFGE). The map spans nearly 8 Mb of genomic DNA, and the estimated average distance between each marker is roughly 290 kb. The p13 band of chromosome 17 is thought to contain a putative tumor suppressor gene in addition and distal to TP53.

Imprinting analysis of three genes in the Prader-Willi/Angelman region: SNRPN, E6-associated protein, and PAR-2 (D15S225E).

In order to identify genes in the Prader-Willi/Angelman syndrome critical region, radiolabeled cDNA probes from poly(A)+ RNA from mouse tissues were used to identify potential exon-containing genomic DNA fragments in cosmid or phage clones from appropriate yeast artificial chromosomes, and these fragments were subsequently used to screen human cDNA libraries. A mouse brain cDNA probe was effective in detecting control genes of various abundance including small nuclear ribonucleoprotein polypeptide N (SNRPN), hypoxanthine-guanine phosphoribosyl transferase, glyceraldehyde-3-phosphate dehydrogenase, and beta-actin. Two genes mapping within the Angelman syndrome critical region were isolated.

Olfactory receptor gene cluster on human chromosome 17: possible duplication of an ancestral receptor repertoire.

A gene superfamily of olfactory receptors (ORs) has recently been identified in a number of species. These receptors share a seven transmembrane domain structure with many neurotransmitter and hormone receptors, and are likely to underlie the recognition and G-protein-mediated transduction of odorant signals. Previously, OR genes cloned in different species were from random locations in the respective genomes.