Generalized atherosclerosis sparing the transplanted kidney in Schimke disease

Chromatin regulator SMARCAL1 modulates cellular lipid metabolism

Biallelic mutations of the chromatin regulator SMARCAL1 cause Schimke Immunoosseous Dysplasia (SIOD), characterized by severe growth defects and premature mortality. Atherosclerosis and hyperlipidemia are common among SIOD patients, yet their onset and progression are poorly understood. Using an integrative approach involving proteomics, mouse models, and population genetics, we investigated SMARCAL1's role. We found that SmarcAL1 interacts with angiopoietin-like 3 (Angptl3), a key regulator of lipoprotein metabolism. In vitro and in vivo analyses demonstrate SmarcAL1's vital role in maintaining cellular lipid homeostasis. The observed translocation of SmarcAL1 to cytoplasmic peroxisomes suggests a potential regulatory role in lipid metabolism through gene expression. SmarcAL1 gene inactivation reduces the expression of key genes in cellular lipid catabolism. Population genetics investigations highlight significant associations between SMARCAL1 genetic variations and body mass index, along with lipid-related traits. This study underscores SMARCAL1's pivotal role in cellular lipid metabolism, likely contributing to the observed lipid phenotypes in SIOD patients.

Clinical course of post-kidney transplant Schimke immuno-osseous dysplasia

BACKGROUND

Schimke immuno-osseous dysplasia (SIOD) is a rare systemic disease characterized by short stature, proteinuria, and recurrent infections. Patients usually have spondyloepiphyseal dysplasia, and progressive steroid-resistant nephropathy that leads to kidney failure. However, their clinical course after kidney transplantation (KT) is not yet well known. Here, we present our experience with cases of SIOD treated at our institute.

CASE PRESENTATION

Since 2014, three children have been diagnosed with nephropathy resulting from SIOD. They presented with proteinuria in the nephrotic range at 7, 5, and 3 years of age. Focal segmental glomerulosclerosis was confirmed and progressed to kidney failure approximately 2 years after proteinuria was detected. These patients underwent living-donor KT from their parents. After KT, Case 1 lost his graft within 7 months due to multi-organ failure caused by disseminated adenovirus infection and died. Case 2 experienced graft failure 5 years after KT due to acute rejection from poor compliance. In Case 3, the allograft was still functioning 6 years after KT with low-dose tacrolimus single medication (trough level < 5 ng/mL). Extra-renal manifestations progressed regardless of KT, namely, right renal vein thrombosis and pulmonary hypertension in Case 1, severe bilateral hip dysplasia and Moyamoya syndrome in Case 2, and neutropenia and thrombocytopenia in Case 3, in addition to recurrent infection.

CONCLUSION

In SIOD patients, KT is complicated with recurrent infections due to their inherent immune dysfunction. Additionally, extra-renal symptoms may render the patients morbid despite the recovery of kidney function.

Moyamoya Syndrome in Schimke Immune-Osseous Dysplasia: A Rare Association

Schimke immuno-osseous dysplasia (SIOD) is an uncommon autosomal recessive (AR) spondylo-epiphyseal dysplasia (SED) and its clinical course and phenotype are yet to be properly described. The phenotypic presentation is quite varied with involvement of the renal, skeletal, vascular, immune, and hematopoietic systems being the most common presentation. We describe a 19-year-old female who presented with adolescent-onset brain and skeletal involvement without renal manifestations. Based on imaging and clinical features, she was diagnosed with a case of SIOD. There is no definitive treatment yet for this disorder, however, clinicians should be aware of this disorder so that adequate counseling and symptomatic management, especially in controlling hypertension and dyslipidemia, can be provided to the affected patients.

Different phenotypes of Schimke immuno-osseous dysplasia (SIOD) in two sisters with the same mutation in the SMARCAL1 gene: case reports

BACKGROUND

Schimke immuno-osseous dysplasia (SIOD) is a very rare autosomal recessive genetic disease caused by mutations in the SMARCAL1 gene. It is characterized by spondyloepiphyseal dysplasia, T-cell immunodeficiency, hypercromic nevi, hypercholesterolemia and steroid-resistant nephrotic syndrome with progressive renal failure to end-stage kidney disease.

CASE PRESENTATION

We report two cases of SIOD in sisters, diagnosed after the debut of nephrotic syndrome. Both had a personal history of short stature, acetabular hip dysplasia and hypercholesterolemia. The first case, a 6 year-old girl, presented peripheral refractory edema, severe arterial hypertension and progressive decrease of the glomerular filtration rate. Steroid-resistance of nephrotic syndrome was confirmed, treated with tacrolimus without response. Renal function worsened over the following 4 months, so haemodialysis was started. Her sister, a 5 years-old girl, had steroid-resistant nephrotic syndrome, who is currently with normal blood pressure and normal renal function under enalapril treatment. In view of the suspicion of SIOD, the genetic studies were carried out, revealing the same mutation in homozygosis.

CONCLUSIONS

SIOD has a variable expression with multi-systemic involvement with a short life expectancy. The early diagnosis is important, which can encourage the early start of treatment and anticipation of complications that may be life-threatening.

Schimke immunoosseous dysplasia and management considerations for vascular risks

Schimke immunoosseous dysplasia (SIOD) is a multisystemic condition characterized by early arteriosclerosis and progressive renal insufficiency, among other features. Many SIOD patients have severe, migraine-like headaches, transient neurologic attacks, or cerebral ischemic events. Cerebral events could be exacerbated or precipitated by hypertension, and it is unclear how these are related to arteriosclerotic changes as dyslipidemia is also a feature of SIOD. The correlation between hypercholesterolemia and cardiovascular risk in SIOD is unclear. Also, the etiology and management of headaches is not well characterized. Here we report our clinical observations in the management of SIOD in a patient who was diagnosed in school age despite early signs and symptoms. We describe biallelic variants, including a previously unreported c.1931G>A (p.Arg644Gln) variant in SMARCAL1. We specifically investigated whether migraine-like headaches and progressive nephropathy may be related to blood pressure dysregulation. We found a correlation between tighter blood pressure regulation using ambulatory blood pressure monitoring and a subjective decrease in headache symptoms. We discuss blood pressure medication management in SIOD. We also characterize dyslipidemia relative to atherosclerosis risks and provide new management strategies to consider for optimizing care.

Increased Wnt and Notch signaling: a clue to the renal disease in Schimke immuno-osseous dysplasia?

Background

Schimke immuno-osseous dysplasia (SIOD) is a multisystemic disorder caused by biallelic mutations in the SWI/SNF-related matrix-associated actin-dependent regulator of chromatin, subfamily A-like 1 (SMARCAL1) gene. Changes in gene expression underlie the arteriosclerosis and T-cell immunodeficiency of SIOD; therefore, we hypothesized that SMARCAL1 deficiency causes the focal segmental glomerulosclerosis (FSGS) of SIOD by altering renal gene expression. We tested this hypothesis by gene expression analysis of an SIOD patient kidney and verified these findings through immunofluorescent analysis in additional SIOD patients and a genetic interaction analysis in Drosophila.

Results

We found increased expression of components and targets of the Wnt and Notch signaling pathways in the SIOD patient kidney, increased levels of unphosphorylated β-catenin and Notch1 intracellular domain in the glomeruli of most SIOD patient kidneys, and genetic interaction between the Drosophila SMARCAL1 homologue Marcal1 and genes of the Wnt and Notch signaling pathways.

Conclusions

We conclude that increased Wnt and Notch activity result from SMARCAL1 deficiency and, as established causes of FSGS, contribute to the renal disease of most SIOD patients. This further clarifies the pathogenesis of SIOD and will hopefully direct potential therapeutic approaches for SIOD patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-016-0519-7) contains supplementary material, which is available to authorized users.

Internal carotid artery surgical revascularization in a pediatric patient with Schimke immuno-osseous dysplasia

Schimke immuno-osseous dysplasia (SIOD) is a rare autosomal recessive disorder characterized by spondyloepiphyseal dysplasia, episodic lymphopenia, renal failure, and cerebrovascular disease secondary to arteriosclerosis and myointimal hyperplasia. In this paper the authors report the first known application of internal carotid artery (ICA) surgical revascularization to relieve a high-grade focal stenosis of the ICA in a pediatric patient, a 6-year-old boy with SIOD. The clinical presentation, imaging features, operative technique, and postoperative course are described and the molecular genetics, pathophysiology, and treatment considerations in SIOD are discussed.

Dental abnormalities and preventive oral care in Schimke immuno-osseous dysplasia

BACKGROUND

Schimke immuno-osseous dysplasia (SIOD) is a rare, severe, autosomal recessive disorder that results in spondyloepiphyseal dysplasia, renal dysfunction, immunodeficiency, facial dysmorphism and growth failure. Little is known about oral features associated with SIOD. Some of the dental anomalies encountered are specific to SIOD and have only been reported in individuals with SIOD.

CASE REPORT

This paper describes the clinical and radiographic dental manifestations of SIOD in two Caucasian brothers. Both lived to be about 10 years old. After a variety of symptoms were reported, a diagnosis of SIOD was finally made when the brothers were, respectively, 5 and 8 years old. At that time, dental anomalies, such as dyschromia, bulbous crowns, short and thin roots, had not been taken into account to establish the diagnosis. However, knowledge of the dental features characteristic of this disease could have helped make the diagnosis. Although both were caries- and periodontal disease-free, special attention was focused on prevention, including dietary counselling, plaque control, oral hygiene instructions and the use of fluoridated toothpaste.

FOLLOW-UP

The two patients were followed every 6 months, for over 2 years (until their death), by both a private dentist and a university hospital dentist, which helped them maintain good oral health. Oral hygiene was assessed at each appointment and fissure sealants were placed by the private practitioner on their first permanent molars.

CONCLUSION

This report describes dental anomalies specific to SIOD that could facilitate diagnosis. Clinicians and dentists should work in collaboration to diagnose and treat children with SIOD. These patients require regular and specific dental management because of their fragile health and their characteristic dental anomalies. Ideally, preventive visits should be scheduled every 6 months in addition to curative visits as needed.

Novel SMARCAL1 bi-allelic mutations associated with a chromosomal breakage phenotype in a severe SIOD patient

PURPOSE

Chromosomal instability syndromes include a group of rare diseases characterized by defective DNA-damage-response and increased risk of chromosomal breakage. Patients display defects in the recognition and/or repair of DNA damage, with a subsequent high rate of malignancies and abnormal gene rearrangements. Other clinical manifestations, such as immunodeficiency, neurodevelopmental delay and skeletal abnormalities, are present in some of these syndromes. We studied a patient with profound T-lymphocyte defect, neurodevelopmental delay, facial dysmorphism, nephrotic syndrome and spondyloepiphyseal bone dysplasia typical of SIOD.

METHODS

Karyotype and chromosome fragility assays on patients' peripheral blood mononuclear cells showed an abnormal rate of spontaneous breaks. Cell cycle analysis of patient's fibroblasts following replication stress induced by hydroxyhurea revealed a delay in their release from S-phase to G2. When using higher concentrations of hydroxyhurea no patient fibroblast colonies could survive, compared with control fibroblasts. Whole-exome sequencing revealed novel compound heterozygote mutations in SMARCAL1 gene, resulting in putative frame shifts of encoded SMARCAL1 from each allele and no detected protein in patient's cells. The patient's youngest brother was found to have similar manifestations of SIOD but of less severity, including short stature, facial dysmorphism and typical osseous dysplasia, but no clinical findings suggestive of immunodeficiency and no chromosomal fragility. Similar to his sister, the brother carries both bi-allelic mutations in SMARCAL1 gene.

CONCLUSIONS

We present here the first evidence of intrinsic chromosomal instability in a severe SMARCAL1-deficient patient with a clinical picture of SIOD. Our results are consistent with the recently outlined role of SMARCAL1 protein in DNA damage response.

Dental abnormalities in Schimke immuno-osseous dysplasia

Described for the first time in 1971, Schimke immuno-osseous dysplasia (SIOD) is an autosomal-recessive multisystem disorder that is caused by bi-allelic mutations of SMARCAL1, which encodes a DNA annealing helicase. To define better the dental anomalies of SIOD, we reviewed the records from SIOD patients with identified bi-allelic SMARCAL1 mutations, and we found that 66.0% had microdontia, hypodontia, or malformed deciduous and permanent molars. Immunohistochemical analyses showed expression of SMARCAL1 in all developing teeth, raising the possibility that the malformations are cell-autonomous consequences of SMARCAL1 deficiency. We also found that stimulation of cultured skin fibroblasts from SIOD patients with the tooth morphogens WNT3A, BMP4, and TGFβ1 identified altered transcriptional responses, raising the hypothesis that the dental malformations arise in part from altered responses to developmental morphogens. To the best of our knowledge, this is the first systematic study of the dental anomalies associated with SIOD.

Reduced elastogenesis: a clue to the arteriosclerosis and emphysematous changes in Schimke immuno-osseous dysplasia?

BACKGROUND

Arteriosclerosis and emphysema develop in individuals with Schimke immuno-osseous dysplasia (SIOD), a multisystem disorder caused by biallelic mutations in SMARCAL1 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like 1). However, the mechanism by which the vascular and pulmonary disease arises in SIOD remains unknown.

METHODS

We reviewed the records of 65 patients with SMARCAL1 mutations. Molecular and immunohistochemical analyses were conducted on autopsy tissue from 4 SIOD patients.

RESULTS

Thirty-two of 63 patients had signs of arteriosclerosis and 3 of 51 had signs of emphysema. The arteriosclerosis was characterized by intimal and medial hyperplasia, smooth muscle cell hyperplasia and fragmented and disorganized elastin fibers, and the pulmonary disease was characterized by panlobular enlargement of air spaces. Consistent with a cell autonomous disorder, SMARCAL1 was expressed in arterial and lung tissue, and both the aorta and lung of SIOD patients had reduced expression of elastin and alterations in the expression of regulators of elastin gene expression.

CONCLUSIONS

This first comprehensive study of the vascular and pulmonary complications of SIOD shows that these commonly cause morbidity and mortality and might arise from impaired elastogenesis. Additionally, the effect of SMARCAL1 deficiency on elastin expression provides a model for understanding other features of SIOD.

Improved outcome with immunosuppressive monotherapy after renal transplantation in Schimke-immuno-osseous dysplasia

SIOD is a multisystem disorder caused by a mutant chromatin remodelling protein. The main clinical findings are spondyloepiphyseal dysplasia with disproportionate growth restriction, defective cellular immunity, and steroid-resistant nephrotic syndrome secondary to biopsy proven FSGS leading to ESRF. Concerning ESRF, kidney transplantation is the therapy of choice since FSGS does not recur in the graft. However, with respect to the underlying immune disorder and the increased susceptibility to life threatening infections, the question of the optimal immunosuppressive therapy after renal transplantation remains unresolved. Under conventional immunosuppressive regimens some SIOD patients have developed severe disseminated cutaneous papilloma virus infections or EBV associated lymphoproliferative disease. We present several cases of children with SIOD (four of five had SMARCAL1 mutations) and monotherapy maintenance immunosuppression after renal transplantation and compare them with 13 patients from the SIOD registry. We have found that post-renal transplantation immunosuppressive monotherapy results in a good outcome with a reduced number of severe infections. Due to the underlying immunodeficiency in SIOD, limited immunosuppression may be possible without increasing the risk of acute or chronic rejection.

Neurologic phenotype of Schimke immuno-osseous dysplasia and neurodevelopmental expression of SMARCAL1

Schimke immuno-osseous dysplasia (OMIM 242900) is an uncommon autosomal-recessive multisystem disease caused by mutations in SMARCAL1 (swi/snf-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like 1), a gene encoding a putative chromatin remodeling protein. Neurologic manifestations identified to date relate to enhanced atherosclerosis and cerebrovascular disease. Based on a clinical survey, we determined that half of Schimke immuno-osseous dysplasia patients have a small head circumference, and 15% have social, language, motor, or cognitive abnormalities. Postmortem examination of 2 Schimke immuno-osseous dysplasia patients showed low brain weights and subtle brain histologic abnormalities suggestive of perturbed neuron-glial migration such as heterotopia, irregular cortical thickness, incomplete gyral formation, and poor definition of cortical layers. We found that SMARCAL1 is highly expressed in the developing and adult mouse and human brain, including neural precursors and neuronal lineage cells. These observations suggest that SMARCAL1 deficiency may influence brain development and function in addition to its previously recognized effect on cerebral circulation.

Cerebellar atrophy in Schimke-immuno-osseous dysplasia

Schimke-immuno-osseous dysplasia is an autosomal-recessive multisystem disorder with the prominent clinical features disproportionate growth failure, progressive renal failure, and T-cell immunodeficiency. Neurological symptoms caused by transient ischemic attacks (TIAs) and strokes are a typical clinical finding in severe SIOD. Cerebral ischemia and white matter changes, moyamoya phenomena and absence of a cerebellar hemisphere and partial absence of the cerebellar vermis have been described in patients with severe SIOD. We present three SIOD patients with atrophy of the caudal parts of the cerebellar vermis (posterior lobule) and of the cerebellar hemispheres. We hypothesize that these cerebellar abnormalities are a continuum of the ongoing vascular disease in severe SIOD.

Schimke immunoosseous dysplasia: suggestions of genetic diversity

Schimke immunoosseous dysplasia (SIOD), which is characterized by prominent spondyloepiphyseal dysplasia, T-cell deficiency, and focal segmental glomerulosclerosis, is a panethnic autosomal recessive multisystem disorder with variable expressivity. Biallelic mutations in switch/sucrose nonfermenting (swi/snf) related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like 1 (SMARCAL1) are the only identified cause of SIOD. However, among 72 patients from different families, we identified only 38 patients with biallelic mutations in the coding exons and splice junctions of the SMARCAL1 gene. This observation, the variable expressivity, and poor genotype-phenotype correlation led us to test several hypotheses including modifying haplotypes, oligogenic inheritance, or locus heterogeneity in SIOD. Haplotypes associated with the two more common mutations, R820H and E848X, did not correlate with phenotype. Also, contrary to monoallelic SMARCAL1 coding mutations indicating oligogenic inheritance, we found that all these patients did not express RNA and/or protein from the other allele and thus have biallelic SMARCAL1 mutations. We hypothesize therefore that the variable expressivity among patients with biallelic SMARCAL1 mutations arises from environmental, genetic, or epigenetic modifiers. Among patients without detectable SMARCAL1 coding mutations, our analyses of cell lines from four of these patients showed that they expressed normal levels of SMARCAL1 mRNA and protein. This is the first evidence for nonallelic heterogeneity in SIOD. From analysis of the postmortem histopathology from two patients and the clinical data from most patients, we propose the existence of endophenotypes of SIOD.

Schimke immuno-osseous dysplasia: a clinicopathological correlation

BACKGROUND

Schimke immuno-osseous dysplasia (SIOD) is a fatal autosomal recessive disorder caused by loss-of-function mutations in swi/snf-related matrix-associated actin-dependent regulator of chromatin, subfamily a-like 1 (SMARCAL1).

METHODS

Analysis of detailed autopsies to correlate clinical and pathological findings in two men severely affected with SIOD.

RESULTS

As predicted by the clinical course, T cell deficiency in peripheral lymphoid organs, defective chondrogenesis, focal segmental glomerulosclerosis, cerebral ischaemic lesions and premature atherosclerosis were identified. Clinically unexpected findings included a paucity of B cells in the peripheral lymphoid organs, emperipolesis-like (penetration of one cell by another) abnormalities in the adenohypophysis, fatty infiltration of the cardiac right ventricular wall, pulmonary emphysema, testicular hypoplasia with atrophy and azospermia, and clustering of small cerebral vessels.

CONCLUSIONS

A regulatory role for the SMARCAL1 protein in the proliferation of chondrocytes, lymphocytes and spermatozoa, as well as in the development or maintenance of cardiomyocytes and in vascular homoeostasis, is suggested. Additional clinical management guidelines are recommended as this study has shown that patients with SIOD may be at risk of pulmonary hypertension, combined immunodeficiency, subcortical ischaemic dementia and cardiac dysfunction.

Membranous nephropathy in Schimke immuno-osseous dysplasia

Schimke immuno-osseous dysplasia is a rare autosomal recessive multi-system disorder, with clinical features of growth retardation, spondylo-epiphyseal dysplasia, nephrotic syndrome and immunodeficiency beginning in childhood. Here, we report a new case, in a 10-year-old boy with characteristic symptoms of Schimke immuno-osseous dysplasia. The patient presented with short stature and, later, developed nephrotic syndrome and peritonitis. In addition, he had perinuclear anti-neutrophilic cytoplasmic antibody (p-ANCA)-positive arthritis. Renal pathology of the patients with this disease usually show focal segmental glomerulonephritis, whereas our patient had membranous nephropathy, which has not previously been reported.

Schimke immuno-osseous dysplasia: a cell autonomous disorder?

SMARCAL1 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like protein 1) encodes a SWI/SNF ATP-dependent chromatin remodeling protein. Mutations in SMARCAL1 cause the autosomal-recessive multisystem disorder Schimke immuno-osseous dysplasia (SIOD); this suggests that the SMARCAL1 protein is involved in the development or maintenance of multiple organs. Disease within these many tissues could arise by a cell autonomous or a cell non-autonomous mechanism. Consistent with a cell autonomous mechanism, we did not find any disease recurrence in transplanted organs or protection of other tissues by the organ grafts. In order to better understand the role of SMARCAL1 during normal development and in the pathogenesis of SIOD, we characterized the spatial and temporal expression of the murine homolog (Smarcal1). The Smarcal1 mRNA and protein were expressed throughout development and in all tissues affected in patients with SIOD including the bone, kidney, thymus, thyroid, tooth, bone marrow, hair, eye, and blood vessels. Significantly, the expression profile of Smarcal1 in the mouse has led us to reexamine and identify novel pathology in our patient population resulting in changes in the clinical management of SIOD. The expression of Smarcal1 in affected tissues and the non-recurrence of disease in grafted organs lead us to hypothesize a cell autonomous function for SMARCAL1 and to propose tissue-specific mechanisms for the pathophysiology of SIOD.

R561C missense mutation in the SMARCAL1 gene associated with mild Schimke immuno-osseous dysplasia

Autosomal-recessive Schimke immuno-osseous dysplasia (SIOD) characterized by spondyloepiphyseal dysplasia, focal-segmental glomerulosclerosis (FSGS), T-cell immunodeficiency and facial dysmorphism is caused by defects in the SMARCAL1 gene. The gene product is involved in the transcriptional regulation of other genes. A 12-year-old boy of consanginous Turkish descent developed disproportionate short stature from spondyloepiphyseal dysplasia at the age of 6 and nephrotic syndrome at the age of 10 years. Renal biopsy revealed FSGS, the kidney function was normal, T-lymphocytes were diminished without infectious complications, and he has had no cerebral ischemia. Analysis of the patient's SMARCAL1 gene revealed a novel homozygous C1798T transition leading to a R561C substitution. The parents and two healthy sisters were found to be heterozygous. A younger brother, who is also homozygous for the mutation, is clinically asymptomatic and has no proteinuria at the age of 18 months. Still, his CD4 cells are diminished. For SMARCAL1 mutations a clear genotype-phenotype correlation has been reported: severe SIOD with in utero or early-childhood onset leading to end-stage renal disease within a few years is caused by nonsense, frame shift or splice mutations. Many patients die from infections and cerebrovascular insults during childhood. Mild SIOD manifests later and progresses more slowly without infectious or cerebral vascular complications--the underlying defect being missense mutations in all three patients reported so far. The novel R561C missense mutation in our patient with mild SIOD is additional evidence for the genotype-phenotype correlation reported for SMARCAL1 mutations.

Mitochondrial function in schimke-immunoosseous dysplasia

Schimke-immunoosseous dysplasia (SIOD) is a multisystemic disorder caused by a mutation of a putative chromatin remodelling protein. Spondyloepiphyseal dysplasia with disproportionate growth deficiency, nephrotic syndrome with focal and segmental glomerulosclerosis, defective cellular immunity, and transient ischemic attacks are major clinical features in the severe form of SIOD. In the present study we tested the hypothesis that mitochondrial dysfunction may be an underlying pathophysiologic mechanism in this multisystemic disease. Mitochondrial parameters were studied in blood (lactate, pyruvate, ketone bodies, alanine) and in urine (organic acids) of four patients with the severe form of SIOD. Activities of respiratory chain enzymes were measured spectrophotometrically in fibroblasts of two of these patients. In patients with the severe form of SIOD normal concentrations of lactate as well as normal lactate/pyruvate- and ketone-body ratios were found in plasma. Alanine, the long-term parameter for lactate, was normal as well; metabolites of the citrate cycle were not found in the urine. Activities of respiratory chain enzymes I-V were not significantly reduced in fibroblasts from two patients with the severe form of SIOD. There was no evidence for mitochondrial dysfunction in SIOD. The underlying pathophysiology of SIOD remains unclear.

Association of migraine-like headaches with Schimke immuno-osseous dysplasia

Schimke immuno-osseous dysplasia (SIOD) is characterized by spondyloepiphyseal dysplasia, nephropathy, and T-cell deficiency. SIOD is caused by mutations in the putative chromatin remodeling protein SMARCAL1. We report an 8-year-old boy with SIOD and recurrent, severe, refractory migraine-like headaches. Through a retrospective questionnaire-based study, we found that refractory and severely disabling migraine-like headaches occur in nearly half of SIOD patients. We have also found that the vasodilator minoxidil provided symptomatic relief for one patient. We hypothesize that these headaches may arise from an intrinsic vascular, neuroimmune, or neurovascular defect resulting from loss of SMARCAL1 function.

Schimke-immuno-osseous dysplasia: New mutation with weak genotype-phenotype correlation in siblings

Schimke-immuno-osseous dysplasia (SIOD) is a multisystem disorder with the following consistent clinical features: spondyloepiphyseal dysplasia with disproportional growth deficiency, nephrotic syndrome with focal and segmental glomerulosclerosis, and defective cellular immunity. Transitory ischemic attacks due to vaso-occlusive processes are complications in some patients with severe SIOD. Recently, mutations of SMARCAL1, which encodes a putative chromatin remodelling protein, have been associated with SIOD. Patients with milder disease were observed to harbor a missense mutation on each allele, whereas patients with a severe form of the disease were predicted to have at least one allele with a nonsense, frameshift or splicing mutation. We report two brothers who are both compound heterozygous for the mutations 836 T>C and 2542 G>T detected in exons 4 and 17, respectively. We demonstrate the lack of genotype-phenotype correlation in these patients as one brother shows some features of the severe form while the other does not. Neither clinical nor molecular findings can fully predict the clinical course of SIOD.