Genetic analysis of Shwachman-Diamond syndrome: phenotypic heterogeneity in patients carrying identical SBDS mutations.
Shwachman-Diamond syndrome (SDS) is a rare hereditary disorder characterized by pancreatic exocrine insufficiency, bone marrow dysfunction and skeletal changes. Recently, the cause of SDS was identified as mutations of Shwachman-Bodian-Diamond syndrome gene (SBDS) and most mutations are caused by gene conversion between SBDS and its highly homologous pseudogene. Clinical variations especially in skeletal and bone marrow abnormalities are well known in this syndrome. To study the relationship between SBDS mutation and its clinical features, we analyzed 9 Japanese patients including one sibling and detected the three different SBDS mutations in 7 patients: a mutation that disrupts the donor splice site of intron 2, deletes 8 bp of the exon 2 and produces premature termination (258+2 T > C), a dinucleotide change that replaces a lysine at 62 nd amino acid to a termination codon (183-184 TA > CT), and a 4-bp deletion that causes premature termination by frameshift (292-295 delAAAG). The 5 patients represent compound heterozygotes of the 258+2 T > C and 183-184 TA > CT mutations. One patient is a compound heterozygote of the 258+2 T > C and 292-295 delAAAG mutations, and in the remaining one case only a 258+2 T > C mutation could be detected. Thus, the 258+2 T > C and 183-184 TA > CT mutations are prevalent among Japanese patients. No mutations were found in two cases, despite the clinical features. Of the 7 patients with SBDS mutations, persistent hematologic abnormalities and skeletal changes were not observed in 3 and 2 patients, respectively. Notably, clinical variations are present even among the patients with the identical genotype: compound heterozygotes of the 258+2 T > C and 183-184 TA > CT mutations. Further study will be required to explain the clinical heterogeneity.
Kawakami
Takako
T
Department of Pediatrics, Yamagata University School of Medicine, Yamagata, Japan.
Mitsui
Tetsuo
T
Kanai
Masayo
M
Shirahata
Emi
E
Sendo
Dai
D
Kanno
Miyako
M
Noro
Mizuka
M
Endoh
Mikiya
M
Hama
Asahito
A
Tono
Chikako
C
Ito
Etsuro
E
Tsuchiya
Shigeru
S
Igarashi
Yutaka
Y
Abukawa
Daiki
D
Hayasaka
Kiyoshi
K
D001483:Base Sequence; D001855:Bone Marrow Diseases / Q000235:genetics*; D001842:Bone and Bones / Q000002:abnormalities*; D002648:Child; D002675:Child, Preschool; D002875:Chromosomes / Q000648:ultrastructure; D004247:DNA / Q000737:chemistry; D004252:DNA Mutational Analysis; D017931:DNA Primers / Q000737:chemistry; D010188:Exocrine Pancreatic Insufficiency / Q000235:genetics*; D005091:Exons; D005260:Female; D016368:Frameshift Mutation; D017353:Gene Deletion; D014644:Genetic Variation; D006579:Heterozygote; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007438:Introns; D007564:Japan; D007621:Karyotyping; D008239:Lysine / Q000737:chemistry; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D009841:Oligonucleotides; D010009:Osteochondrodysplasias / Q000235:genetics*; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D013577:Syndrome
D017931:DNA Primers; D009841:Oligonucleotides; D011506:Proteins; D012333:RNA, Messenger; C470521:SBDS protein, human; D004247:DNA; D008239:Lysine