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V P Johnson

Publications and source records attributed to V P Johnson.

14 recordsLinked to original sources
PubMed1992

Molecular detection of a 4p deletion using PCR-based polymorphisms: a technique for the rapid detection of the Wolf-Hirschhorn syndrome.

Wolf-Hirschhorn syndrome (WHS) results from a deletion of part of chromosome 4p. The region of 4p consistently deleted in WHS is near the tip of 4p. Two loci in this region D4S95 and D4S125 are associated with highly informative VNTR polymorphisms and were recently converted to allow PCR-based screening. PCR analysis was used successfully to identify a small de novo deletion of 4p in a patient suspected of having WHS. This procedure allows a rapid and accurate confirmation of 4p deletions in cases where cytogenetics alone cannot provide a clear answer.

Abnormalities, Multiple↗
PubMed1992

Natural history of mosaic trisomy 14 syndrome.

Trisomy 14 mosaicism produces a distinct phenotype. Among the 13 reported and 2 additional patients, the following findings were present in more than 90%: growth retardation (15/15), psychomotor retardation (10/10), broad nose (13/14), "dysplastic" and/or apparently low-set ears (15/15), micrognathia (15/15), short neck (11/12), congenital heart disease (14/15), and micropenis and cryptorchidism (6/6). Other frequent findings were prominent forehead (12/14), hypertelorism (8/13), narrow palpebral fissure (7/9), large mouth (10/14), cleft or highly arched palate (10/14), body asymmetry (8/12), and abnormal skin pigmentation (6/10). Sex ratio was 6M:9F. Four patients died before age 4 months, while at least 2 patients survived through teens. One boy died at age 3 years following cardiac surgery. One girl with tetralogy of Fallot showed a remarkable improvement in health after Blalock-Taussig procedure. Although the surviving patients showed moderate growth and mental retardation, the oldest surviving woman at 29 years demonstrates functional language and appropriate self help skills.

Abnormalities, Multiple↗
PubMed1992

Human genome project.

Genome n. [gene plus chromosome] the complete set of chromosomes containing all of the genes of an organism. For man this set of 46 per cell stretches to a 6 foot strand of DNA. Within this string of 3 billion nucleotide bases are 100,000 genes. Utilizing a 4 letter alphabet (Adenine, Guanine, Cytosine, Thymine), genes provide the blueprint for the amino acid sequence of structural protein (cell membrane, connective tissue, etc) or functional protein (hormones, enzymes, transmitters, etc). DNA replication guarantees exact gene copies and chromosome meiosis and crossing over guarantees varied gene combinations. This forms the basis for the similarity and the diversity of all of humankind: the similarity needed to perpetuate successful genes and the diversity needed for genes to respond to the weeding out process of evolution.

Ethics, Medical↗
PubMed1991

Pelizaeus-Merzbacher disease: clinical and DNA-linkage study of an extended family.

We describe a 5-generation family of 6 individuals with Pelizaeus-Merzbacher disease, Type I. DNA linkage study was done to establish carrier status. Two loci, DXS162 and DXYS1, were informative in this family for carrier determination. The highest lod score is that for PMD-DXYS1 (Z = 1.421 at theta = 0). The carrier probability can only be defined as likely or unlikely in the absence of an established recombination frequency.

Chromosome Mapping↗
PubMed1991

Duplication of the distal part of the long arm of chromosome 1.

A case of dup(1)(q42----qter) is reported. A literature review of duplication of the distal third of chromosome 1 with breakpoints at various sites, 1q23, 1q25, 1q32, and 1q42, was undertaken. Clinical similarities and differences based on the size of the duplicated segment and other associated deficiencies are summarized.

Abnormalities, Multiple↗
PubMed1991

Sex chromosome marker: clinical significance and DNA characterization.

Two patients are described with a virtually identical marker sex chromosome that was so small as to defy classification by conventional cytogenetic studies. DNA hybridization with Y probes allows classification into Y or non-Y, and in situ hybridization with X centromere specific sequences, into X or non-X. One patient was proven to have a Y fragment, and the second, an X fragment. DNA characterization is important since prognosis and clinical management depends on proper identification of the small marker sex chromosome.

Child, Preschool↗
PubMed1979

Trisomy 14 mosaicism: case report and review.

Complete or partial trisomy 14 is compatible with life. However, in the former case, mosaicism is probably always present. A case of trisomy 14 mosaicism is reported. Comparisons are made with other trisomy 14, trisomy 14 mosaicism, and duplication 14q cases previously reported. As a group, they share some clinical manifestations. The phenotype consists of multiple congenital anomalies, including microcephaly, broad nose, wide mouth, high or cleft palate, micrognathia, congenital heart disease, intrauterine growth retardation, and mental retardation. The present patient also has asthma, eczema, and developmental asymmetry.

Abnormalities, Multiple↗
PubMed1976

The Wolf-Hirschhorn (4p-) syndrome.

In a review of 43 cases, the phenotypic spectrum of the Wolf-Hirschhorn syndrome is analyzed and the frequency of clinical anomalies is tabulated. The characteristic features are intrauterine growth retardation, severe psychomotor retardation, typical facies, and various major and minor congenital anomalies suggestive of a midline fusion defect. Diagnosis is established by karyotyping- deletion of the short arm of chromosome No. 4. All cases so far reported are de novo occurrences with no sibling involvement and normal parents. Prognosis is poor, with death in the first 2 years of life in 34% of cases, usually due to cardiac decompensation or infection. Psyhomotor retardation is profound, so that heroic medical efforts probably need to be reconsidered.

Abnormalities, Multiple↗
PubMed1975

Smith-Lemli-Opitz syndrome: review and report of two affected siblings.

This paper reports two siblings with the Smith-Lemli-Opitz syndrome and reviews the literature on the subject. SLOS is a syndrome of multiple congenital anomalies with mental and growth retardation, unusual facies, genito-urinary and hand and foot abnormalities inherited as an autosomal recessive trait.

Abnormalities, Multiple↗
PubMedDate not supplied

Martin-Bell syndrome segregating in a large kindred with normal transmitting males: clinical, cytogenetic, and linkage study.

We report on a large kindred with 10 mentally retarded, fra(X) positive males and 2 normal transmitting males. Clinical findings include variable degrees of facial anomalies, macroorchidism, behavioral characteristics, and cognitive deficiencies. The affected grandsons were fra(X) positive while their obligate carrier mothers and transmitting grandfathers were fra(X) negative. DNA-restriction fragment length polymorphism (RFLP) linkage study was undertaken to find informative markers to identify heterozygotes or hemizygotes. The problems encountered in genetic counselling, by the absence of established criteria for diagnosis, are discussed.

Adolescent↗