Role of CAMK2D in neurodevelopment and associated conditions.

The calcium/calmodulin-dependent protein kinase type 2 (CAMK2) family consists of four different isozymes, encoded by four different genes-CAMK2A, CAMK2B, CAMK2G, and CAMK2D-of which the first three have been associated recently with neurodevelopmental disorders. CAMK2D is one of the major CAMK2 proteins expressed in the heart and has been associated with cardiac anomalies. Although this CAMK2 isoform is also known to be one of the major CAMK2 subtypes expressed during early brain development, it has never been linked with neurodevelopmental disorders until now. Here we show that CAMK2D plays an important role in neurodevelopment not only in mice but also in humans. We identified eight individuals harboring heterozygous variants in CAMK2D who display symptoms of intellectual disability, delayed speech, behavioral problems, and dilated cardiomyopathy. The majority of the variants tested lead to a gain of function (GoF), which appears to cause both neurological problems and dilated cardiomyopathy. In contrast, loss-of-function (LoF) variants appear to induce only neurological symptoms. Together, we describe a cohort of individuals with neurodevelopmental disorders and cardiac anomalies, harboring pathogenic variants in CAMK2D, confirming an important role for the CAMK2D isozyme in both heart and brain function.

Incomplete spinal cord injury following minor trauma in two siblings with spondylocostal dysostis type 6.

Biallelic pathogenic variants of the RIPPLY2 gene have been recognized to cause a subtype of autosomal recessive spondylocostal dysostosis (SCDO6), characterized by predominant cervical spine malformation with minor or absent involvement of the ribs. To date, RIPPLY2 associated SCDO6 has been described in ten patients in five studies with accompanying clinical symptoms varying from transient and recurrent torticollis to flaccid quadriplegia. Here, we describe two additional patients in one family in which the c.A238T:p.Arg80* RIPPLY2 mutation in the homozygous state, was associated with severe malformation of the posterior elements of the cervical vertebral column. In both cases neurological symptoms occurred early in life due to spinal cord compromise. These two cases, in keeping with previous reports, highlight the early and progressive natural history of cervical deformity in this rare skeletal dysplasia and the need for close neurological and radiological surveillance. Surgical decision-making needs to carefully balance the need for early intervention to protect spinal cord function on one hand, with the problem of bone malformation and skeletal immaturity on the other.

5q35 duplication syndrome: Narrowing the critical region on the distal side and further evidence of intrafamilial variability and expression.

The key features of patients with a microduplication 5q35.2q35.3 (including the NSD1 gene) are short stature, microcephaly, mild developmental delay, behavioral problems, digital anomalies and congenital anomalies of internal organs. This core phenotype can be viewed as the reversed phenotype of Sotos syndrome, which is caused by a microdeletion in the same chromosomal region or a pathogenic variant in the NSD1 gene, and includes tall stature and macrocephaly, developmental delay, and epilepsy. Here, we report on a patient and his mother, both with a 5q35.2q35.3 duplication, adding a fifth family to the recently published overview of 39 patients of Quintero-Rivera et al. Our patient had several congenital anomalies, intrauterine growth restriction with a persisting short stature, while his mother was only mildly affected with decreased growth parameters. In addition, he had hemophagogocytic lymphohistiocytosis (HLH) triggered by Haemophilus influenzae and was recently diagnosed with Ewing sarcoma. Our cases carry the smallest duplication published (ca 332 kb, arr[hg19] 5q35.2q35.3(176493106-176824785)x3) further narrowing the distal side of the critical region of the 5q35.2q35.3 duplication. Besides broadening the clinical phenotypic spectrum, our report indicates that the 5q35.2q35.3 microduplication also shows a large intra-familial variability and expression.

Case Report: Developmental Delay and Acute Neuropsychiatric Episodes Associated With a de novo Mutation in the CAMK2B Gene (c.328G>A p.Glu110Lys).

Mutations in the genes encoding calcium/calmodulin dependent protein kinase II (CAMK2) isoforms cause a newly recognized neurodevelopmental disorder (ND), for which the full clinical spectrum has yet to be described. Here we report the detailed description of a child with a de novo gain of function (GoF) mutation in the gene Ca/Calmodulin dependent protein kinase 2 beta (CAMK2B c.328G > A p.Glu110Lys) who presents with developmental delay and periodic neuropsychiatric episodes. The episodes manifest as encephalopathy with behavioral changes, headache, loss of language and loss of complex motor coordination. Additionally, we provide an overview of the effect of different medications used to try to alleviate the symptoms. We show that medications effective for mitigating the child's neuropsychiatric symptoms may have done so by decreasing CAMK2 activity and associated calcium signaling; whereas medications that appeared to worsen the symptoms may have done so by increasing CAMK2 activity and associated calcium signaling. We hypothesize that by classifying CAMK2 mutations as "gain of function" or "loss of function" based on CAMK2 catalytic activity, we may be able to guide personalized empiric treatment regimens tailored to specific CAMK2 mutations. In the absence of sufficient patients for traditional randomized controlled trials to establish therapeutic efficacy, this approach may provide a rational approach to empiric therapy for physicians treating patients with dysregulated CAMK2 and associated calcium signaling.

Unraveling the Genetics of Congenital Diaphragmatic Hernia: An Ongoing Challenge.

Congenital diaphragmatic hernia (CDH) is a congenital structural anomaly in which the diaphragm has not developed properly. It may occur either as an isolated anomaly or with additional anomalies. It is thought to be a multifactorial disease in which genetic factors could either substantially contribute to or directly result in the developmental defect. Patients with aneuploidies, pathogenic variants or de novo Copy Number Variations (CNVs) impacting specific genes and loci develop CDH typically in the form of a monogenetic syndrome. These patients often have other associated anatomical malformations. In patients without a known monogenetic syndrome, an increased genetic burden of de novo coding variants contributes to disease development. In early years, genetic evaluation was based on karyotyping and SNP-array. Today, genomes are commonly analyzed with next generation sequencing (NGS) based approaches. While more potential pathogenic variants are being detected, analysis of the data presents a bottleneck-largely due to the lack of full appreciation of the functional consequence and/or relevance of the detected variant. The exact heritability of CDH is still unknown. Damaging de novo alterations are associated with the more severe and complex phenotypes and worse clinical outcome. Phenotypic, genetic-and likely mechanistic-variability hampers individual patient diagnosis, short and long-term morbidity prediction and subsequent care strategies. Detailed phenotyping, clinical follow-up at regular intervals and detailed registries are needed to find associations between long-term morbidity, genetic alterations, and clinical parameters. Since CDH is a relatively rare disorder with only a few recurrent changes large cohorts of patients are needed to identify genetic associations. Retrospective whole genome sequencing of historical patient cohorts using will yield valuable data from which today's patients and parents will profit Trio whole genome sequencing has an excellent potential for future re-analysis and data-sharing increasing the chance to provide a genetic diagnosis and predict clinical prognosis. In this review, we explore the pitfalls and challenges in the analysis and interpretation of genetic information, present what is currently known and what still needs further study, and propose strategies to reap the benefits of genetic screening.

Retinol status of newborn infants is associated with congenital diaphragmatic hernia.

OBJECTIVE: Genetic analyses in humans suggest a role for retinoid-related genes in the pathogenesis of congenital diaphragmatic hernia (CDH). The goal of this study was to investigate the vitamin A status of mothers and their newborns in association with CDH. METHODS: We conducted a hospital-based, case-control study with 22 case and 34 control mothers and their newborns. In maternal and cord blood samples, retinol and retinol-binding protein (RBP) levels were measured with high-performance liquid chromatography and an enzyme-linked immunosorbent assay, respectively. Univariate and multivariate logistic regression analyses were performed to determine crude and adjusted risk estimates. RESULTS: Case newborns had significantly lower levels of retinol (0.60 vs 0.76 µmol/L; P=.003) and RBP (5.42 vs 7.11 mg/L; P=.02) than did control newborns. The multivariate logistic regression analysis showed lower levels of retinol and RBP in association with CDH risk; the odds ratio for retinol levels of <15th percentile (<0.61 µmol/L) was 11.11 (95% confidence interval: 2.54-48.66; P=.001), and that for RBP levels of <15th percentile (<4.54 mg/L) was 4.00 (95% confidence interval: 1.00-15.99; P=.05). Retinol and RBP levels were not different between case and control mothers. CONCLUSIONS: CDH is strongly associated with low retinol and RBP levels in newborns, independent of maternal retinol status. This is an important finding supporting the idea that human CDH is linked with abnormal retinoid homeostasis.

PROP1, HESX1, POU1F1, LHX3 and LHX4 mutation and deletion screening and GH1 P89L and IVS3+1/+2 mutation screening in a Dutch nationwide cohort of patients with combined pituitary hormone deficiency.

BACKGROUND/AIMS: Mutation frequencies of genes involved in combined pituitary hormone deficiency (CPHD) vary substantially between populations. The HYPOPIT study aims to obtain an overall picture of known and new genetic defects and variations in a nationwide cohort of Dutch (mostly) sporadic CPHD patients. METHODS: We screened 79 CPHD patients from 78 families (regardless of MRI and hormonal phenotype) for mutations and deletions in PROP1, HESX1, POU1F1, LHX3 and LHX4, as well as the P89L and IVS3+1/+2 mutations in GH1, recently described to cause pituitary hormone impairment in addition to GH deficiency. RESULTS: We did not find any mutation or deletion in PROP1, HESX1, LHX3 or LHX4, nor GH1 P89L and GH1 IVS3+1/+2 mutations. Among 12 patients with a typical 'POU1F1 phenotype', 1 patient was formerly known to have a POU1F1 mutation. This results in a POU1F1 mutation frequency in these patients of 8.3%. CONCLUSION: Thorough screening for mutations and deletions in PROP1, HESX1, POU1F1, LHX3, LHX4, as well as screening for GH1 P89L or GH1 IVS3+1/+2 mutations, did not reveal any genetic defect in our cohort of CPHD patients except for one formerly known POU1F1 mutation in 1 patient. Future research should focus on alternative explanations for CPHD, like other genes or environmental factors.

Genetic screening of a Dutch population with isolated GH deficiency (IGHD).

OBJECTIVE: Five per cent to 30% of cases of idiopathic isolated GH deficiency (IGHD) have first-degree relatives with short stature, which is suggestive of a genetic aetiology. The HYPOPIT study aimed to obtain an overall picture of gene encoding pituitary GH (GH1) and gene encoding GH releasing hormone-receptor (GHRHR) defects in a Dutch IGHD cohort and to relate them with clinical parameters. DESIGN, PATIENTS AND MEASUREMENTS: Genetic analysis was performed of exons and exon-intron boundaries of GH1 and GHRHR in 89 Caucasian IGHD patients from 81 families, using denaturing high-performance liquid chromatography (dHPLC), DNA sequencing and multiplex ligation-dependent probe amplification. In addition, we performed functional studies on novel identified GH1 exonic variants. RESULTS: Five different heterozygous GH1 mutations were present in 5 out of 81 participating families (6.1%), whereas no mutations in GHRHR were found. Patients with IGF-I SDS < -4.0 and peak GH levels < 5.7 mU/l had a mutation frequency of 40%, in contrast to 6.8% in patients with only one criterion, and 0.0% in patients with none of these criteria (P = 0.00007). Five new GH1 and two GHRHR variants were also identified; two of them (GH1 F92L and D153H) caused a marked reduction of GH secretion in vitro. CONCLUSION: GH1 and GHRHR mutations are rare in Caucasian Dutch IGHD patients, which suggests the involvement of other genetic determinants in the aetiology of IGHD. IGF-I < -4.0 and peak GH levels < 5.7 mU/l are strong predictors of GH1 mutations in the studied population.