Shwachman-Diamond syndrome: clinical, radiological and sonographic findings

Structural variation and missense mutation in SBDS associated with Shwachman-Diamond syndrome

Background

Shwachman–Diamond syndrome (SDS) is an autosomal recessive ribosomopathy caused mainly by compound heterozygous mutations in SBDS. Structural variation (SV) involving the SBDS locus has been rarely reported in association with the disease. We aimed to determine whether an SV contributed to the pathogenesis of a case lacking biallelic SBDS point mutations.

Case presentation

Whole exome sequencing was performed in a patient with SDS lacking biallelic SBDS point mutations. Array comparative genomic hybridization and Southern blotting were used to seek SVs across the SBDS locus. Locus-specific polymerase chain reaction (PCR) encompassing flanking intronic sequence was also performed to investigate mutation within the locus. RNA expression and Western blotting were performed to analyze allele and protein expression. We found the child harbored a single missense mutation in SBDS (c.98A > C; p.K33T), inherited from the mother, and an SV in the SBDS locus, inherited from the father. The missense allele and SV segregated in accordance with Mendelian expectations for autosomal recessive SDS. Complementary DNA and western blotting analysis and locus specific PCR support the contention that the SV perturbed SBDS protein expression in the father and child.

Conclusion

Our findings implicate genomic rearrangements in the pathogenesis of some cases of SDS and support patients lacking biallelic SBDS point mutations be tested for SV within the SBDS locus.

Shwachman-Diamond syndrome

Shwachman-Diamond syndrome (SDS) is a rare autosomal recessive disorder with exocrine pancreatic insufficiency, bone marrow failure and skeletal abnormalities. Patients frequently present failure to thrive, susceptibility to infections and short stature. A persistent or intermittent neutropenia occurs in 88-100% of patients. Bone marrow biopsy usually reveals a hypoplastic specimen with varying degrees of hypoplasia and fat infiltration. Some patients may develop myeloblastic syndrome and acute myeloblastic leukemia. The genetic defect in SDS has been identified in 2002. The osteoporosis is increased in patients with SDS, and also, bone malformations are included among the primary characteristics of the syndrome. The severity and location change with age and sexes. The typical characteristics include the following: secondary ossification centers delayed appearance, metaphysis enlargement and irregularity (very common in childhood, particularly in coastal and femur), growth cartilage progressive thinning and irregularity (possibly asymmetric growth), generalized osteopenia with cortical thinning. We describe a clinical case regarding an SDS patient with severe bone abnormalities and treated surgically for corrective osteotomy. The persistent or intermittent neutropenia that characterized this disease and the consequent risk of infection is a contraindication for short stature correction and limbs lengthening.

Dermatofibrosarcoma protuberans arising in the context of Shwachman-Diamond syndrome

Dermatofibrosarcoma protuberans (DFSP) is an uncommon malignant spindle-cell tumor usually presenting in adulthood. The epidemiology of DFSP has recently been reviewed, and there have been 152 reported cases of DFSP in patients below the age of sixteen. We present the case of a DFSP arising in a young patient with Shwachman-Diamond syndrome (SDS).

Congenital and developmental pancreatic anomalies: ultrasound, computed tomography, and magnetic resonance imaging features

The purpose of this article is to provide an overview of the most common anatomic, congenital, and developmental anomalies of the pancreas. Familiarity with the imaging appearances of these anomalies as well as the range of normal appearance is important to differentiate them from other conditions, especially since some of these variants are commonly encountered. Basic knowledge of the normal embryology is of utmost importance to be able to recognize these disorders.

Shwachman-Diamond syndrome is associated with low-turnover osteoporosis

INTRODUCTION

Shwachman-Diamond syndrome (SDS) is an autosomal recessive disorder characterized by exocrine pancreatic insufficiency and bone marrow dysfunction. These result in malabsorption and hematological abnormalities. A skeletal dysplasia is also an integral feature of SDS. The present study assessed prevalence and determinants of osteopenia and osteoporosis in patients with SDS and disease-causing mutations in the SBDS gene.

MATERIALS AND METHODS

Eleven patients (8 males) aged from 5 to 37 years (median 16.7 years) with a genetically confirmed diagnosis of SDS were assessed for fracture history, bone mineral content (BMC), lean tissue mass (LTM) and bone mineral density (BMD) (Hologic Discovery A), osteoporotic vertebral changes, and for blood biochemistry and hematological parameters. Iliac crest bone biopsies were obtained from four patients for histology and histomorphometry.

RESULTS

The main findings were: (1) markedly reduced BMD Z-scores at the lumbar spine (median -2.1, range -4.4 to -0.8), proximal femur (median -1.3, range -2.2 to -0.7) and, whole body (median -1.0, range -2.8 to +0.6), and reduced Z-scores for height-adjusted BMC/LTM ratio (median -0.9, range -3.6 to +1.1); (2) vertebral compression fractures in three patients; and (3) blood biochemistry suggestive of mild vitamin D and vitamin K deficiency. Bone biopsies in four patients showed significant low-turnover osteoporosis with reduced trabecular bone volume, low numbers of osteoclasts and osteoblasts, and reduced amount of osteoid.

CONCLUSIONS

The results suggest that in addition to the skeletal dysplasia, SDS is associated with a more generalized bone disease characterized by low bone mass, low bone turnover and by vertebral fragility fractures. Osteoporosis may result from a primary defect in bone metabolism, and could be related to the bone marrow dysfunction and neutropenia.

Disorders of the pediatric pancreas: imaging features

The purpose of this manuscript is to provide an overview of the normal development of the pancreas as well as pancreatic pathology in children. Diagnostic imaging plays a major role in the evaluation of the pancreas in infants and children. Familiarity with the range of normal appearance and the diseases that commonly affect this gland is important for the accurate and timely diagnosis of pancreatic disorders in the pediatric population. Normal embryology is discussed, as are the most common congenital anomalies that occur as a result of aberrant development during embryology. These include pancreas divisum, annular pancreas, agenesis of the dorsal pancreatic anlagen and ectopic pancreatic tissue. Syndromes that can manifest pancreatic pathology include: Beckwith Wiedemann syndrome, von Hippel-Lindau disease and autosomal dominant polycystic kidney disease. Children and adults with cystic fibrosis and Shwachman-Diamond syndrome frequently present with pancreatic insufficiency. Trauma is the most common cause of pancreatitis in children. In younger children, unexplained pancreatic injury must always alert the radiologist to potential child abuse. Pancreatic pseudocysts are a complication of trauma, but can also be seen in the setting of acute or chronic pancreatitis from other causes. Primary pancreatic neoplasms are rare in children and are divided into exocrine tumors such as pancreatoblastoma and adenocarcinoma and into endocrine or islet cell tumors. Islet cell tumors are classified as functioning (insulinoma, gastrinoma, VIPoma and glucagonoma) and nonfunctioning tumors. Solid-cystic papillary tumor is probably the most common pancreatic tumor in Asian children. Although quite rare, secondary tumors of the pancreas can be associated with certain primary malignancies.

Shwachman-Diamond syndrome

Shwachman-Diamond syndrome (SDS), described just under 40 years ago, is a rare, autosomal-recessive disorder usually manifest in infancy and characterized by exocrine pancreatic insufficiency, short stature, and bone marrow dysfunction. Additional clinical features include metaphyseal dysostosis, epiphyseal dysplasia, immune dysfunction, liver disease, growth failure, renal tubular defects, insulin-dependent diabetes mellitus, and psychomotor retardation. Hematological manifestations other than neutropenia include anemia, raised fetal hemoglobin (HbF) levels, thrombocytopenia, impaired neutrophil chemotaxis, and aplastic anemia; as with other constitutional bone marrow failure syndromes, there is a predilection to malignant myeloid transformation. No unifying pathogenetic mechanism(s) has yet been shown to be responsible for SDS, although new insights into the molecular, genetic, and cellular basis of this rare disease have recently been described.

Shwachman-Diamond syndrome in a Mexican family

Shwachman-Diamond Syndrome (SDS) is an inherited condition with multisystemic abnormalities including pancreatic exocrine dysfunction, neutropenia, short stature, and skeletal abnormalities. In this report, we describe the case of a 14-year-old female with a history of neutropenia, pancreatic exocrine insufficiency and pancreatic endocrine sufficiency, pancreatic lipomatosis (10), and the development of myeloid leukemia. Postmortem examination revealed a high probability of SDS. We also describe the clinical findings in the patient's six siblings, suggesting this as a familial form of SDS. Because the gene(s) responsible for this syndrome have not yet been identified, genetic confirmation is not yet possible. This is the first report in the literature of a Mexican family with probable SDS.