Disruption of NEUROD2 causes a neurodevelopmental syndrome with autistic features via cell-autonomous defects in forebrain glutamatergic neurons.

While the transcription factor NEUROD2 has recently been associated with epilepsy, its precise role during nervous system development remains unclear. Using a multi-scale approach, we set out to understand how Neurod2 deletion affects the development of the cerebral cortex in mice. In Neurod2 KO embryos, cortical projection neurons over-migrated, thereby altering the final size and position of layers. In juvenile and adults, spine density and turnover were dysregulated in apical but not basal compartments in layer 5 neurons. Patch-clamp recordings in layer 5 neurons of juvenile mice revealed increased intrinsic excitability. Bulk RNA sequencing showed dysregulated expression of many genes associated with neuronal excitability and synaptic function, whose human orthologs were strongly associated with autism spectrum disorders (ASD). At the behavior level, Neurod2 KO mice displayed social interaction deficits, stereotypies, hyperactivity, and occasionally spontaneous seizures. Mice heterozygous for Neurod2 had similar defects, indicating that Neurod2 is haploinsufficient. Finally, specific deletion of Neurod2 in forebrain excitatory neurons recapitulated cellular and behavioral phenotypes found in constitutive KO mice, revealing the region-specific contribution of dysfunctional Neurod2 in symptoms. Informed by these neurobehavioral features in mouse mutants, we identified eleven patients from eight families with a neurodevelopmental disorder including intellectual disability and ASD associated with NEUROD2 pathogenic mutations. Our findings demonstrate crucial roles for Neurod2 in neocortical development, whose alterations can cause neurodevelopmental disorders including intellectual disability and ASD.

22q11.2 microduplication syndrome with associated esophageal atresia/tracheo-esophageal fistula and vascular ring.

This case report describes a patient with a 22q11.2 duplication. His features, which include VACTERL association with an esophageal atresia/tracheo-esophageal fistula and a vascular ring, expand the previously described phenotype for this duplication.

Mitochondrial enzyme dysfunction in autism spectrum disorders; a novel biomarker revealed from buccal swab analysis.

AIM: Mitochondrial function studies in autism spectrum disorders (ASD) have detected skeletal muscle mitochondrial enzyme deficiencies in respiratory complex (RC) activities. As a muscle biopsy is expensive and invasive, we assessed RC-I and RC-IV activities in buccal swabs. METHODS: 92 children with ASD and 68 controls were studied with immunocapture for RC-I and microspectrophotometry for RC-IV. RESULTS: Significant RC activity deficiencies were found in 39 (42%) ASD patients (p < 0.01) and more prevalent in more severe cases. Aberrant RC overactivity was seen in 9 children. RC-I/RC-IV activity ratio was significantly increased in 64% of the entire ASD cohort including 76% of those more severely affected (p < 0.05). CONCLUSION: Buccal swab analysis revealed extensive RC abnormalities in ASD providing a noninvasive biomarker to assess mitochondrial function in ASD patients.

A novel 2q37 microdeletion containing human neural progenitors genes including STK25 results in severe developmental delay, epilepsy, and microcephaly.

2q37 microdeletion syndrome is a rare syndrome characterized by neurodevelopmental delay, bone, cardiovascular, and neurological alterations. This syndrome is typically associated with loss of genetic material of approximately 100 genes in the 2q37 band. However, the genes associated with neurodevelopmental phenotype in this syndrome are still unknown. We identified a deleted region of 496 kb by whole genome array CGH in a patient who fulfilled criteria for 2q37 microdeletion syndrome with developmental delay, microcephaly, hypoplasia of the corpus callosum, hand wringing, toe walking, and seizures. The deleted segment contains genes that are highly expressed in the developing human cortical plate and the subventricular zone (SVZ) in vivo and human neural progenitors in vitro, including SEPT2, THAP4, ATG4B, PPP1R7, and STK25. Network analysis revealed that STK25 was the most interacting gene associated with neural development in this deletion. Our report narrows the likely causative genomic region for microcephaly and neurodevelopmental delay in 2q37 microdeletion syndrome to a small genomic region enriched with neural progenitor genes that may represent an important locus for the development of the human cortex and corpus callosum.

Co-occurrence of non-mosaic trisomy 22 and inherited balanced t(4;6)(q33;q23.3) in a liveborn female: case report and review of the literature.

Trisomy 22 is the third most common autosomal trisomy occurring in about 0.4% of all clinically recognized pregnancies. Complete non-mosaic trisomy 22 is extremely rare in live births. Most affected children die before one year of age. To date, only 29 liveborn cases have been reported and none has carried an additional genetic lesion. In this report, we describe the clinical presentation, cytogenetic, and cytogenomic findings in a liveborn female with complete non-mosaic trisomy 22 as well as a paternally inherited, balanced reciprocal chromosomal rearrangement t(4;6)(q33;q23.3). The proband manifested features commonly seen in individuals with non-mosaic trisomy 22 such as intrauterine growth retardation (IUGR), single umbilical artery, cranial abnormalities, short neck, cleft lip and palate, dysmorphic ears, hypoplastic nipples, digital malformation, congenital heart defects, dysplastic kidneys, and genital anomalies. In addition, she had lobar holoprosencephaly, aqueductal stenosis, and limb and eye problems that have not been associated with complete trisomy 22 in previous reports. She died at 35 days of age of complex heart disease and renal failure. We are hereby expanding the cytogenetic and clinical spectrum of this rare chromosome disorder. Clinical features of liveborn children with non-mosaic trisomy 22 are reviewed and compared to those in our proband. The impact of genomic content in relation to the survival of trisomies in humans is also discussed.

Fraternal twins with autism, severe cognitive deficit, and epilepsy: diagnostic role of chromosomal microarray analysis.

A 7-year-old child presented with atypical absence epilepsy. He also had autism and severe cognitive deficit. As part of his diagnostic workup, a chromosomal microarray analysis was performed, which showed novel biallelic deletions in the neurexin 1 gene (NRXN1). His fraternal twin sister, who also had autism and cognitive impairment, was subsequently found to have the same biallelic deletions. Deletions included a 272-282kb loss at band 2p16.3 in one allele and a smaller 135-174-kb loss on the second allele. Neurexin 1 (NRXN1) is a cell adhesion protein, forming a synaptic complex with neuroligin. This signals a pathway that is critical for activity-dependent synaptic transmission. Mutations in this gene have been associated with autism and neurodevelopmental delay. Although there are many reports of heterozygous mutations with variable expressivity, only 3 cases with biallelic NRXN1 mutations have been previously reported, all of which have a more severe phenotype. We report 2 siblings with biallelic deletions, both of which affect the promoter region and exons 1-5 in the α-NRXN1 isoform, which has a role in the Ca(2+)-dependent release of neurotransmitters in the central nervous system. Our cases expand the phenotype of biallelic α NRXN 1 mutations and emphasize the important role of NRXN1 in autism and intellectual disability. Chromosomal microarray analysis should be the clinical standard in all specialties for first-tier genetic testing in autistic spectrum disorders.

Mitochondrial dysfunction in autism.

Using data of the current prevalence of autism as 200:10,000 and a 1:2000 incidence of definite mitochondrial (mt) disease, if there was no linkage of autism spectrum disorder (ASD) and mt disease, it would be expected that 1 in 110 subjects with mt disease would have ASD and 1 in 2000 individuals with ASD would have mt disease. The co-occurrence of autism and mt disease is much higher than these figures, suggesting a possible pathogenetic relationship. Such hypothesis was initially suggested by the presence of biochemical markers of abnormal mt metabolic function in patients with ASD, including elevation of lactate, pyruvate, or alanine levels in blood, cerebrospinal fluid, or brain; carnitine level in plasma; and level of organic acids in urine, and by demonstrating impaired mt fatty acid ß-oxidation. More recently, mtDNA genetic mutations or deletions or mutations of nuclear genes regulating mt function have been associated with ASD in patients or in neuropathologic studies on the brains of patients with autism. In addition, the presence of dysfunction of the complexes of the mt respiratory chain or electron transport chain, indicating abnormal oxidative phosphorylation, has been reported in patients with ASD and in the autopsy samples of brains. Possible pathogenetic mechanisms linking mt dysfunction and ASD include mt activation of the immune system, abnormal mt Ca(2+) handling, and mt-induced oxidative stress. Genetic and epigenetic regulation of brain development may also be disrupted by mt dysfunction, including mt-induced oxidative stress. The role of the purinergic system linking mt dysfunction and ASD is currently under investigation. In summary, there is genetic and biochemical evidence for a mitochondria (mt) role in the pathogenesis of ASD in a subset of children. To determine the prevalence and type of genetic and biochemical mt defects in ASD, there is a need for further research using the latest genetic technology such as next-generation sequencing, microarrays, bioinformatics, and biochemical assays. Because of the availability of potential therapeutic options for mt disease, successful research results could translate into better treatment and outcome for patients with mt-associated ASD. This requires a high index of suspicion of mt disease in children with autism who are diagnosed early.

Tetrasomy 13q32.2qter due to an apparent inverted duplicated neocentric marker chromosome in an infant with hemangiomas, failure to thrive, laryngomalacia, and tethered cord.

BACKGROUND: Approximately 100 small supernumerary marker chromosomes (sSMCs) with a non-α-satellite neocentromere structure have been reported in the literature. Of the few derived from chromosome 13, five have consisted of inverted duplicated segment 13q32qter. CASE REPORT: We herein describe the sixth case, characterized by genome wide SNP array, conventional cytogenetics and FISH studies. The de novo occurrence of the marker, the poor prognosis and the presence of hemangiomas are consistent with previous cases. CONCLUSION: We hereby expand the clinical spectrum of this rare cytogenetic disorder and suggest a possible mechanism for the pathogenesis of associated congenital vascular malformations.

Metabolic profiling of total homocysteine and related compounds in hyperhomocysteinemia: utility and limitations in diagnosing the cause of puzzling thrombophilia in a family.

We describe a family illustrating the diagnostic difficulties occurring when pyridoxine-responsive cystathionine beta-synthase (CBS) deficiency presents with thrombotic disease without associated ocular, skeletal, or CNS abnormalities, a situation increasingly recognized. This family had several thromboembolic episodes in two generations with apparently inconstant elevations of plasma total homocysteine (tHcy). When taking (sometimes even low amounts) of pyridoxine, the affected family members had low-normal tHcy and normal values for cystathionine, methionine, and cysteine. Withdrawal of vitamin therapy was necessary before lower cystathionine, elevated methionine, and decreased cysteine became apparent, a pattern suggestive of CBS deficiency, leading to the finding that the affected members were each compound heterozygotes for CBS p.G307S and p.P49L. To assist more accurate diagnosis of adults presenting with thrombophilia found to have elevated tHcy, the patterns of methionine-related metabolites in CBS-deficient patients are compared in this article to those in patients with homocysteine remethylation defects, including inborn errors of folate or cobalamin metabolism, and untreated severe cobalamin or folate deficiency. Usually serum cystathionine is low in subjects with CBS deficiency and elevated in those with remethylation defects. S-Adenosylmethionine and S-adenosylhomocysteine are often markedly elevated in CBS deficiency when tHcy is above 100 umol/L. We conclude that there are likely other undiagnosed, highly B6-responsive adult patients with CBS deficiency, and that additional testing of cystathionine, total cysteine, methionine, and S-adenosylmethionine will be helpful in diagnosing them correctly and distinguishing CBS deficiency from remethylation defects.

Transplanted bone marrow mononuclear cells and MSCs impart clinical benefit to children with osteogenesis imperfecta through different mechanisms.

Transplantation of whole bone marrow (BMT) as well as ex vivo-expanded mesenchymal stromal cells (MSCs) leads to striking clinical benefits in children with osteogenesis imperfecta (OI); however, the underlying mechanism of these cell therapies has not been elucidated. Here, we show that non-(plastic)-adherent bone marrow cells (NABMCs) are more potent osteoprogenitors than MSCs in mice. Translating these findings to the clinic, a T cell-depleted marrow mononuclear cell boost (> 99.99% NABMC) given to children with OI who had previously undergone BMT resulted in marked growth acceleration in a subset of patients, unambiguously indicating the therapeutic potential of bone marrow cells for these patients. Then, in a murine model of OI, we demonstrated that as the donor NABMCs differentiate to osteoblasts, they contribute normal collagen to the bone matrix. In contrast, MSCs do not substantially engraft in bone, but secrete a soluble mediator that indirectly stimulates growth, data which provide the underlying mechanism of our prior clinical trial of MSC therapy for children with OI. Collectively, our data indicate that both NABMCs and MSCs constitute effective cell therapy for OI, but exert their clinical impact by different, complementary mechanisms. The study is registered at www.clinicaltrials.gov as NCT00187018.

Noonan syndrome due to a SHOC2 mutation presenting with fetal distress and fatal hypertrophic cardiomyopathy in a premature infant.

We report on a patient with Noonan syndrome due to SHOC2 missense mutation predicting p.Ser2Gly, recently described in association with Noonan syndrome. The male infant presented with fetal distress requiring premature delivery at 32 weeks and was noted to have dysmorphic features, edema, hepatosplenomegaly, leukocytosis, thrombocytopenia, and respiratory distress following birth. An echocardiogram revealed hypertrophic cardiomyopathy with left ventricular outflow tract obstruction. The infant's cardiac lesion rapidly progressed, and he was discharged home for palliative care. Clinical testing of genes causative of Noonan syndrome and related disorders detected the previously reported, pathogenic, de novo SHOC2 missense mutation predicting p.Ser2Gly. The patient's cardiac findings and features were not typical for those individuals previously reported with this SHOC2 mutation and thus expand the clinical phenotype.

A strategy for single nucleotide polymorphism analysis of chimerism for somatic cell therapy.

BACKGROUND AIMS: Chimerism is an important outcome measure in hematopoietic cell transplantation as well as somatic cell therapy. Commonly used methods to estimate chimerism are restricted by either gender or inefficient sensitivity. In principle, real-time polymerase chain reaction (PCR)-based assays can be used to assess single nucleotide polymorphisms (SNP), which are a vast resource of molecular markers, and such assays demonstrate a substantially higher sensitivity (0.001%), but the specificity is unclear because of a low-level signal from mismatched sequences. METHODS: In this study, we cloned 14 pairs of SNP selected from the SNP HapMap database and examined the specificity and sensitivity of their detection by real-time PCR using two primer/fluorescent probe pairs to allow genotyping of the two possible variant alleles. Clinical donor-recipient pairs from 18 families were used to explore the efficacy of using SNP assays to measure chimerism. RESULTS: We found that the polymorphic nucleotide influences the ability to distinguish the signal generated by the target and mismatched sequences. Moreover, the specific fluorescent reporter probe can affect the difference in signal intensity between the target and mismatched sequences. Real-time PCR SNP assays can attain a sensitivity of 0.1-0.5% with 100% specificity. When comparing possible clinical donor-recipient pairs, we found an average 3.3 out of 14 SNP were informative. CONCLUSIONS: By optimal selection of the polymorphic sequences and fluorescent reporter, the real-time PCR SNP assay is superior to the short-tandem repeat chimerism assay and broadly applicable. This strategy may be applied in future clinical trials of bone marrow cell therapy.

Cell therapy for disorders of bone.

Bone marrow transplantation (BMT) has changed the course of treatment for an array of diseases, including disorders of bone. Hematopoietic stem cells (HSC) within the marrow are known to be the precursors of osteoclastic bone cells, and trials of BMT in osteopetrosis, a disorder characterized by a deficiency of osteoclasts, have resulted in significant clinical improvement in patients. The origin of the other major bone cell, the osteoblast, remains uncertain, although studies have identified osteoprogenitor cells within the marrow, leading to further investigation of both mesenchymal stromal cells (MSC) and HSC as candidates for this role. A better understanding of the source of osteoblasts and normal bone metabolism is crucial to efforts to develop effective cell therapy for bone disorders characterized by deficient or abnormal osteoblast function. This review focuses on systemic and local cell therapy in the treatment of several genetic bone disorders and osteoporosis, an acquired disorder caused by abnormal bone metabolism, with the intent of presenting both the progress and challenges associated with this emerging form of therapy. Although the risks of systemic transplantation must be carefully considered, cell therapy for disorders of bone carries the potential for long-term and potentially curative benefits, justifying further intensive research on this important treatment option.

Short-chain acyl-coenzyme A dehydrogenase deficiency.

Short-chain acyl-CoA dehydrogenase deficiency (SCADD) is a disorder of mitochondrial fatty acid oxidation that leads to the accumulation of butyrylcarnitine and ethylmalonic acid in blood and urine. Originally described with a relatively severe phenotype, most patients are now diagnosed through newborn screening by tandem mass spectrometry and remain asymptomatic. Molecular analysis of affected individuals has identified a preponderance of private inactivating point mutations and one common one present in high frequency in individuals of Ashkenazi Jewish ancestry. In addition, two polymorphic variants have been identified that have little affect on enzyme kinetics but impair folding and stability. Individuals homozygous for one of these variants or compound heterozygous for one of each often show an increased level of ethylmalonic acid excretion that appears not to be clinically significant. The combination of asymptomatic affected newborns and the frequent variants can cause much confusion in evaluating and treating individuals with SCADD. The long-term consequences and the need for chronic therapy remain current topics of contention and investigation.

Use of Medicare claims data to measure county-level variation in breast carcinoma incidence and mammography rates.

BACKGROUND: National-level population-based data about breast carcinoma incidence and its association with screening mammography are currently not available. METHODS: Inpatient, hospital outpatient and physician/supplier Medicare claims were used to identify incident cases of breast carcinoma in women > or = 65 years from 1996 to 1997 and calculate county-level incidence rates. The 1994-1995 claims data were used to determine county-level rates of mammography, and determine the correlation with incidence. RESULTS: The median 2-year incidence rate for women > or = 65 was 979/100,000, and substantial variation in incidence between counties was observed. (i.e. 25th percentile 789/100,000, 75th percentile 1186/100,000). Two-year county-level mammography rates also varied among counties (i.e. 25th percentile 30.5%, 75th percentile 40.9%) and were higher in white women than in black women (median 36.8 and 26.3%, respectively). Counties with higher rates of mammography also had higher age-adjusted incidence rates. CONCLUSIONS: Medicare claims may provide an alternative source of population-based data, particularly for areas in which registry data are not readily available, or are of limited scope. The data highlight the geographic variation in incidence and screening rates that may be useful for targeted interventions, and also suggest that mammography remains in a growth phase.