James Skare

Linkage analysis of seven kindreds with the X-linked lymphoproliferative syndrome (XLP) confirms that the XLP locus is near DXS42 and DXS37

SummaryAnalysis of seven kindreds indicates that the XLP locus exhibits 1% recombination with DXS42 (lod = 17.5) and no recombination with DXS37 (lod = 13.3).

Homozygosity for the met30 transthyretin gene in a Turkish kindred with familial amyloidotic polyneuropathy

SummaryA Turkish family is described with two members suffering from familial amyloidotic polyneuropathy. Their transthyretin genes were examined using the polymerase chain reaction, and both patients possessed the met30 mutation in both of their transthyretin genes. In this family, only individuals who are homozygous for the met30 mutation have developed symptoms.

Partial Xq25 deletion in a family with the X-linked lymphoproliferative disease (XLP)

X-linked lymphoproliferative disease (XLP) results in exquisite vulnerability to EBV infection: fatal infectious mononucleosis (IM), acquired hypogammaglobulinemia and/or malignant lymphoma occur invariably following infection with the virus. We have identified the XLP locus using the DXS42 DNA probe having restriction length polymorphisms (RFLP). We report an interstitial deletion involving a portion of the Xq25 region in the X chromosome of an affected male, one sister, and their mother. Concordance has been established between the presence of a deletion and RFLP linkage analysis with the DXS42 probe in the kindred. This finding will contribute substantially to the mapping, cloning, and sequencing of the gene responsible for XLP.

A new mutation causing familial amyloidotic polyneuropathy

The DNA from an individual with familial amyloidotic polyneuropathy was examined. It did not possess any of the mutations which have previously been associated with familial amyloidotic polyneuropathy. However, a novel 7.0 kb Sph I restriction fragment was discovered, and the mutation creating it was localized to exon 3 of the transthyretin gene. This mutation was inherited from a parent, and may result in an amino acid substitution for glu89, his90 or ala91. The patients transthyretin has a lower pI than normal transthyretin.

Detection of X-linked lymphoproliferative disease using molecular and immunovirologic markers

PURPOSE, PATIENTS, AND METHODS Detection of males affected with the X-linked lymphoproliferative disease (XLP) was sought using immunovirologic and molecular genetic linkage techniques. The study population consisted of 20 males in six families with XLP. RESULTS Concordance for detection of affected males was 100% when linkage analysis using DXS42 and DXS37 DNA probes and antibody responses to challenge with bacteriophage phi X174 were both determined. Most affected males showing IgG subclass immune deficiency could not produce antibodies to Epstein-Barr virus nuclear antigen and had deficient responses to challenge with bacteriophage phi X174. CONCLUSION Use of only one of the techniques described can fail to lead to the diagnosis of XLP, because problems can prevail with each individual determination.

Mapping the mutation causing the X-linked lymphoproliferative syndrome in relation to restriction fragment length polymorphisms on Xq

SummaryThe X-linked lymphoproliferative syndrome (XLP) results in fatal infectious mononucleosis, hypogammaglobulinemia, and malignant lymphoma. The mutation has been mapped relative to several restriction fragment length polymorphism (RFLP) markers in the X121-Xq27 vicinity. The DXS37 locus was found to be near both the DXS42 and XLP loci.

A new transthyretin variant from a patient with familial amyloidotic polyneuropathy has asparagine substituted for histidine at position 90

A new transthyretin variant which lost an Sph I cleavage site within exon 3 has been characterized. A 260 bp sequence containing exon 3 was amplified using the polymerase chain reaction, and the variant was found to possess a Bsm I cleavage site not present in normal transthyretin. This led to the conclusion that the histidine at position 90 was replaced by asparagine, and amino acid analysis supported the conclusion. The discovery of this mutation suggests that intermolecular binding between hydrophobic polypeptide loops on the surface of transthyretin can lead to familial amyloidotic polyneuropathy.

Localization of the gene for human heart fatty acid binding protein to chromosome 1p32-1p33

Heart fatty acid binding protein (hFABP) is an abundant 14-kDa cytosolic protein thought to be involved in trafficking of fatty acids from the plasma membrane to sites of β-oxidation in mitochondria and peroxisomes and to the endoplasmic reticulum for lipid synthesis. A human hFABP cDNA isolated by polymerase chain reaction was used as a probe for in situ hybridization to metaphase chromosomes. A fragment of the gene for human hFABP was used as a probe for fluorescence in situ hybridization to metaphase chromosomes. The cDNA and genomic probes both localized the gene for human hFABP to chromosome 1p32-1p33.

A new transthyretin variant (Ser2 sn) associated with familial amyloidosis in a Portuguese patient

The detection and characterization of a new transthyretin (ATTR) variant, Ser23Asn, associated with cardiomyopathy in a Portuguese patient with familial amyloidosis is described. Isoelectric focusing (IEF) of serum from the propositus demonstrated heterozygosity for the presence of wild type and variant ATTR. A combination of mass spectrometric (MS) analyses, including electrospray ionization mass spectrometry (ESI MS), high performance liquid chromatography (HPLC)/ESI MS and matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) performed on the serum-derived TTR were used to identify and locate the amino acid replacement in the variant protein. Genetic mutation analysis by DNA sequencing and allele-specific PCR confirmed this finding.

In Situ Hybridization applied to Waardenburg Syndrome

Multilocus linkage analysis has suggested that the Waardenburg syndrome type 1 (WS1) locus is flanked by placental alkaline phosphatase (ALPP) and fibronectin 1 (FN1). We used fluorescence in situ hybridization (FISH) to map ALPI (intestinal alkaline phosphatase) to 2q36.3-q37.1 and FN1 to 2q34. FISH also showed that a WS1 patient with a de novo interstitial deletion of 2q35-q36.1 retained both API and FN1 on the deleted chromosome. The human PAX3 gene has been shown previously to be mutated in at least two WS1 patients. We mapped a PCR product from the PAX3 gene to 2q35 and found it was absent in the deleted chromosome. Thus, our FISH mapping results confirm the conclusions from previous linkage analysis and support the conclusion that mutation of the PAX3 gene can cause Waardenburg syndrome.