Jing Da Shi

Characterization of mutations in patients with autoimmune polyglandular syndrome type 1 (APS1)

Abstract Autoimmune polyglandular syndrome type 1 (APS1), also known as autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED), is an autosomal recessive disorder characterized by the failure of several endocrine glands as well as nonendocrine organs. The autoimmune regulator (AIRE) gene responsible for APS1 on chromosome 21q22.3 has recently been identified. Here, we have characterized mutations in the AIRE gene by direct DNA sequencing in 16 unrelated APS1 families ascertained mainly from the USA. Our analyses identified four different mutations (a 13-bp deletion, a 2-bp insertion, one nonsense mutation, and one potential splice/donor site mutation) that are likely to be pathogenic. Fifty-six percent (9/16) of the patients contained at least one copy of a 13-bp deletion (1094–1106del) in exon 8 (seven homozygotes and two compound heterozygotes). A nonsense mutation (R257X) in exon 6 was also found in 31.3% (5/16) of the USA patients. These data are important for genetic diagnosis and counseling for families with autoimmune endocrine syndromes.

Molecular cloning and characterization of a novel gene family of four ancient conserved domain proteins (ACDP).

We have recently cloned four novel human genes that encode the ancient conserved domain proteins (ACDP). The full-length cDNA sequence of ACDP1 consists of 5898 bp and encodes a predicted protein of 951 amino acids (AA). The transcript for ACDP2 has 4058 bp of cDNA sequence, encoding a protein of 875 AA. ACDP3 contains 3113 bp of cDNA sequence and encodes a putative protein of 707 AA. ACDP4 contains 4765 bp of cDNA sequence and encodes a protein of 775 AA. The ACDP genes belong to a highly conserved new gene family. The conserved region showed 62.8% of nucleotide sequence identity, and 65.5% of AA identity with 92% of AA homologies among ACDP members. The conserved domain is also found in genes from evolutionarily divergent species from bacteria, yeast, Caenorhabditis elegans, and Drosophila melanogaster to mammals. All ACDP genes except ACDP1 have a ubiquitous expression pattern while ACDP1 expression is restricted to the brain and testis. Immunofluorescence staining of premeablized HeLa cells showed that ACDP proteins are predominantly localized in the nucleus. Sequence homology analyses revealed AA property and structural homologies between the ACD domain and cyclin molecules.

Molecular cloning and characterization of the mouse Acdp gene family

BackgroundWe have recently cloned and characterized a novel gene family named ancient conserved domain protein (ACDP) in humans. To facilitate the functional study of this novel gene family, we have cloned and characterized Acdp, the mouse homologue of the human ACDP gene family.ResultsThe four Acdp genes (Acdp1, Acdp2, Acdp3 and Acdp4) contain 3,631 bp, 3,244 bp, 2,684 bp and 2,743 bp of cDNA sequences, and encode deduced proteins of 951, 874, 713 and 771 amino acids, respectively. The mouse Acdp genes showed very strong homologies (>90%) in both nucleotide and amino acid sequences to their human counterparts. In addition, both nucleotide and amino acid sequences within the Ancient Conserved Domain (ACD) are highly conserved in many different taxonomic species. Particularly, Acdp proteins showed very strong AA homologies to the bacteria CorC protein (35% AA identity with 55% homology), which is involved in magnesium and cobalt efflux. The Acdp genes are widely expressed in all tissues tested except for Acdp1, which is only highly expressed in the brain with low levels of expression in kidney and testis. Immunostaining of Acdp1 in hippocampus neurons revealed a predominant localization on the plasma membrane.ConclusionThe Acdp genes are evolutionarily conserved in diverse species and ubiquitously expressed throughout development and adult tissues suggesting that Acdp may be an essential gene. Acdp showed strong homology to bacteria CorC protein and predominantly localized on the plasma membrane. These results suggest that Acdp is probably a family of proteins involved in ion transport in mammalian cells

High resolution mapping and mutation analyses of candidate genes in the urofacial syndrome (UFS) critical region

The urofacial (Ochoa) syndrome (UFS) characterized by congenital obstructive uropathy and abnormal facial expression is a rare disorder caused by a single recessive disease gene. Our previous studies using homozygosity mapping have located the UFS gene to a genomic interval of approximately 360 kb on chromosome 10q23‐10q24. In this study, we have constructed a genomic sequence map covering the entire UFS interval and narrowed the disease interval to a genomic region of 220 kb that harbor the newly identified ACDP1 gene in addition to part of the GOT1 gene which has already been excluded as a candidate for UFS. Extensive search for mutations in the coding region, the 5′ and 3′ untranslated regions, the promoter region, and the exon/intron junctions failed to identify a pathogenic mutation in UFS patients. Furthermore, our analyses indicated that the same gene on chromosome 10q is responsible for all UFS patients from multiple ethnic groups.

Genetic homogeneity, high-resolution mapping, and mutation analysis of the urofacial (Ochoa) syndrome and exclusion of the glutamate oxaloacetate transaminase gene (GOT1) in the critical region as the disease gene

The urofacial (Ochoa) syndrome (UFS) is a rare autosomal recessive disorder characterized by abnormal facial expression and urinary abnormalities. Previously, we mapped the gene to a genomic interval of approximately 1 cM on chromosome region 10q23-24, using families from Columbia. Here we demonstrate genetic homogeneity of the syndrome through homozygosity mapping in American patients with Irish heritage. We established a physical map and identified novel polymorphic markers in the UFS critical region. Haplotype analysis using the new markers mapped the UFS gene within one YAC clone of 1,410 kb. We also determined the precise location of the gene encoding for glutamate oxaloacetate transaminase (GOT1) within the new UFS critical region and determined its genomic structure. However, mutation analysis excluded GOT1 as a candidate for the UFS gene.

Novel TSHβ subunit gene mutation causing congenital central hypothyroidism in a newborn male

Newborn screening programs that use only high TSH levels as a marker for hypothyroidism may overlook neonates with congenital hypothyroidism (CH) due to TSH deficiency. We sought the cause of TSH deficiency in a neonate with low levels of thyroxine and TSH. The coding region of the TSHbeta gene was amplified and its sequence examined for mutations. Two mutations in exon 3 were identified: 1) a nucleotide deletion of T410 in codon 105 resulting in a frameshift in one allele, and 2) a previously unreported nucleotide deletion of T266 in codon 57, causing a frameshift and a premature stop at codon 62 in the other allele. We describe a compound heterozygous patient with TSHbeta mutations at codons 57 and 105 that interfered with a critical disulfide bond in the TSH molecule and caused CH. State screening programs that measure both T4 and TSH levels have the potential to detect newborns with congenital central hypothyroidism.

Rapid decrease of RNA level of a novel mouse mitochondria solute carrier protein ( Mscp ) gene at 4–5 weeks of age

Abstract. We cloned a novel mouse gene that encodes a protein with homology to the mitochondria solute carrier proteins (Mscp). The major full-length Mscp transcript contains 4112 bp of cDNA and a deduced protein of 338 amino acids. The Mscp protein shares 50%, 40%, and 39% sequence identity with the C. elegans hypothetical protein T26089 and the yeast mitochondria carrier proteins MRS3 and MRS4, respectively. It also showed homology with the uncoupling proteins (UCP1, UCP2, and UCP3; 22%, 24%, and 29% identity, respectively). The protein has six transmembrane domains and three mitochondria energy-transfer protein signature motifs, which are conserved among all the members of mitochondria carrier protein family. Northern analysis indicated that the Mscp gene is highly expressed in the spleen. Using cDNA microarray and Northern analysis, we have shown a significant decrease of the splenic Mscp mRNA levels around 4–5 weeks of age in several mouse strains including C57BL/6J, nonobese diabetic (NOD), and several NOD-congenic mice. These results suggest that the Mscp gene is decreased during splenic lymphocyte maturation in these mice.

Detection of AIRE Mutation in Atypical Autoimmune Polyglandular Syndrome Type 1 (APS1)

We describe several members of a family in which the R257X mutation in the AIRE gene responsible for autoimmune polyglandular syndrome type 1 (APS1) was found. The daughter, who is homozygous for the mutation, presented with a range of clinical pathology, including immunoglobulin deficiencies, mucocutaneous candidiaisis and hypothyroidism. Although this patient does not meet the strict clinical diagnostic criteria of APS1, genetic testing made a definitive diagnosis of APS1 and suggested that other APS1 component diseases may appear in this patient in the future. Our study demonstrates the power of screening for the AIRE mutations in all patients who present with one or more APSl-component diseases; genetic testing may become a part of routine clinical care for all such patients.