Alena Puchmajerova

Pontocerebellar hypoplasia type 1 Clinical spectrum and relevance of EXOSC3 mutations

Objectives: Pontocerebellar hypoplasia with spinal muscular atrophy, also known as PCH1, is a group of autosomal recessive disorders characterized by generalized muscle weakness and global developmental delay commonly resulting in early death. Gene defects had been discovered only in single patients until the recent identification of EXOSC3 mutations in several families with relatively mild course of PCH1. We aim to genetically stratify subjects in a large and well-defined cohort to define the clinical spectrum and genotype–phenotype correlation. Methods: We documented clinical, neuroimaging, and morphologic data of 37 subjects from 27 families with PCH1. EXOSC3 gene sequencing was performed in 27 unrelated index patients of mixed ethnicity. Results: Biallelic mutations in EXOSC3 were detected in 10 of 27 families (37%). The most common mutation among all ethnic groups was c.395A>C, p.D132A, responsible for 11 (55%) of the 20 mutated alleles and ancestral in origin. The mutation-positive subjects typically presented with normal pregnancy, normal birth measurements, and relative preservation of brainstem and cortical structures. Psychomotor retardation was profound in all patients but lifespan was variable, with 3 subjects surviving beyond the late teens. Abnormal oculomotor function was commonly observed in patients surviving beyond the first year. Major clinical features previously reported in PCH1, including intrauterine abnormalities, postnatal hypoventilation and feeding difficulties, joint contractures, and neonatal death, were rarely observed in mutation-positive infants but were typical among the mutation-negative subjects. Conclusion: EXOSC3 mutations account for 30%–40% of patients with PCH1 with variability in survival and clinical severity that is correlated with the genotype.

DiGeorge/velocardiofacial syndrome: FISH studies of chromosomes 22q11 and 10p14, and clinical reports on the proximal 22q11 deletion

DiGeorge anomaly/velocardiofacial syndrome (DG/VCFS) occurs with different deletion intervals on chromosomes 22q11, while the DiGeorge anomaly (with other findings) is seen in patients with deletions of 10p14. The clinical outcome with the common 22q11 deletion (90% of cases) is well known, but the outcome with the less frequent deletion types has not been well documented. Using cytogenetic and fluorescence in situ hybridization (FISH) analysis we studied a series of 295 patients with suspected DG/VCFS. We identified 58 subjects with a 22q11 deletion, and none with a 10p deletion. Fifty‐two subjects had the common deletion, five had the proximal deletion, and one had an atypical proximal deletion due to a 1;22 translocation. We report clinical data of four subjects with the proximal 22q11 microdeletion, and of one patient with the atypical proximal deletion. The anomalies observed with the proximal 22q11 microdeletion fell within the DG/VCFS spectrum. Two females, 6 and 25 years old, had normal mental development. Normal development has been reported with the common 22q11 deletion, but only in a minority of cases. This study may indicate a better intellectual and/or behavioral outcome with the proximal vs. the common 22q11 deletion, rather than a chance finding.

Mutations in STK11 gene in Czech Peutz-Jeghers patients

BackgroundPeutz-Jeghers syndrome (PJS) is an autosomal dominant hereditary disease characterized by mucocutaneous pigmentation and gastrointestinal hamartomatous polyposis. The germline mutations in the serine/threonine kinase 11 (STK11) gene have been shown to be associated with the disease. Individuals with PJS are at increased risk for development of various neoplasms. The aim of the present study was to characterize the genotype and phenotype of Czech patients with PJS.MethodsWe examined genomic DNA of 8 individuals from five Czech families by sequencing analysis of STK11 gene, covering its promotor region, the entire coding region and the splice-site boundaries, and by multiplex ligation-dependent probe amplification (MLPA) assay designed for the identification of large exonic deletions or duplications of STK11 gene.ResultsWe found pathogenic mutations in STK11 gene in two families fulfilling the diagnostic criteria of PJS and in one of three sporadic cases not complying with the criteria. The patient with the frameshift mutation in STK11 gene developed aggressive gastric cancer. No other studied proband has developed a carcinoma so far.ConclusionOur results showed that a germline mutation of STK11 gene can be found not only in probands fulfilling the PJS diagnostic criteria, but also in some sporadic cases not complying with the criteria. Moreover, we observed a new case of aggressive gastric cancer in a young patient with a frameshift mutation of STK11 gene.

Deletions of 9q21.3 including NTRK2 are associated with severe phenotype

Conflict of interests: none. Grant sponsor: Czech Ministry of Health; Grant numbers: NT/14200, DRO UH Motol 00064203; Grant sponsor: European Commission; Grant numbers: CHERISH 223692, CZ.2.16/3.1.00/24022. Correspondence to: Miroslava Hancarova, Department of Biology and Medical Genetics, Charles University 2nd Faculty of Medicine and University Hospital Motol, Plzenska 130/221, 15000 Prague 5, Czech Republic. E-mail: miroslava.hancarova@lfmotol.cuni.cz Article first published online in Wiley Online Library (wileyonlinelibrary.com): 27 October 2014 DOI 10.1002/ajmg.a.36797 TO THE EDITOR:

Coarctation of the aorta in Noonan‐like syndrome with loose anagen hair

Noonan‐like syndrome with loose anagen hair (NS/LAH; OMIM 607721) due to a missense mutation c.4A>G in SHOC2 predicting p.Ser2Gly has been described recently. This condition is characterized by facial features similar to Noonan syndrome, reduced growth, cardiac defects, and typical abnormal hair. We report on a patient with molecularly confirmed NS/LAH with coarctation of the aorta. The girl was precipitously born at 37 weeks of gestation at home and required a 3‐min resuscitation. Increased nuchal translucency and aortic coarctation with a small ventricular septal defect were described prenatally, hypertrophic cardiomyopathy was detected postnatally. The patient presented with facial dysmorphism typical of NS with redundant skin over the nape and on the back. Short stature, relative macrocephaly, failure‐to‐thrive together with dystrophic appearance, developmental delay mainly in motor milestones and very thin, sparse, slow‐growing hair occurred a few weeks after birth. Endocrine evaluation revealed low IGF‐1 levels and borderline growth hormone deficiency. Growth hormone therapy started at 16 months had a partial effect and prevented further growth deterioration. Coarctation of the aorta is not a typical heart defect among individuals with NS/LAH, therefore our observation extends the phenotypic spectrum of this disorder.

Mechanism and genotype-phenotype correlation of two proximal 6q deletions characterized using mBAND, FISH, array CGH, and DNA sequencing.

Proximal 6q deletions have a milder phenotype than middle and distal 6q deletions. We describe 2 patients with non-overlapping deletions of about 15 and 19 Mb, respectively, which subdivide the proximal 6q region into 2 parts. The aberrations were identified using karyotyping and analysed using mBAND and array CGH. The unaffected mother of the first patient carried a mosaic karyotype with the deletion in all metaphases analysed and a small supernumerary marker formed by the deleted material in about 77% of cells. Her chromosome 6 centromeric signal was split between the deleted chromosome and the marker, suggesting that this deletion arose through the centromere fission mechanism. In this family the location of the proximal breakpoint in the centromere prevented cloning of the deletion junction, but the junction of the more distal deletion in the second patient was cloned and sequenced. This analysis showed that the latter aberration was most likely caused by non-homologous end joining. The second patient also had a remarkably more severe phenotype which could indicate a partial overlap of his deletion with the middle 6q interval. The phenotypes of both patients could be partly correlated with the gene content of their deletions and with phenotypes of other published patients.

Fanconi anemia with biallelic FANCD1/BRCA2 mutations – Case report of a family with three affected children

Fanconi anemia, complementation group D1 with bi-allelic FANCD1 (BRCA2) mutations, is a very rare genetic disorder characterized by early onset of childhood malignancies, including acute leukemia, brain cancer and nephroblastoma. Here, we present a case report of a family with 3 affected children in terms of treatment outcome, toxicity and characterization of the malignancies using comprehensive cytogenetic analysis. The first child was diagnosed with T-cell acute lymphoblastic leukemia when he was 11 months old. During chemotherapy, he suffered from repeated pancytopenia, sepsis and severe vincristine polyneuropathy, and 18 months after primary diagnosis, he succumbed to secondary acute monocytic leukemia. The second child was diagnosed with stage 2 triphasic nephroblastoma (Wilms tumor), when he was 3 years and 11 months old. During chemotherapy, he suffered from vincristine polyneuropathy. Currently, he is in complete remission, 29 months following the initial diagnosis. The third child was diagnosed with medulloblastoma with classical histology, when she was 4 years and 5 months old. After the first cycle of chemotherapy, she suffered from prolonged pancytopenia, sepsis and severe skin and mucosal toxicity. Six weeks after primary diagnosis, a first relapse in the posterior fossa was diagnosed, and at 7 and half months after primary diagnosis, a second relapse was diagnosed that led to the patients death. Our case report underscores tumor heterogeneity, treatment toxicity and poor outcome in Fanconi anemia patients of complementation group D1.

Paraganglioma in a 13-year-old girl: a novel SDHB gene mutation in the family?

Paraganglioma (PGL) is a rare tumor that may be found in the abdomen, the thorax, or the head and neck region. Succinate dehydrogenase (SDH, or succinate-coenzyme Q reductase) was recognized as one of the key molecules playing a role in the pathogenesis of the tumor [1]. An enzyme complex bound to the inner mitochondrial membrane, SDH is the only enzyme that participates in both the citric acid cycle and the mitochondrial electron transport chain. It is a heterotetramer divided into three domains: SDHA, the catalytic domain, SDHB, the electron transfer subunit; and SDHC and SDHD, the anchor subunits. Germline mutations in the genes encoding the B, D, and C subunits have recently been recognized as associated with paraganglioma syndromes. These three genes are mapped to 1p36.1wp35 (SDHB), 11q23 (SDHD), and 1q21 (SDHC ). Thus, familial PGL syndromes can be classified according to the mutations in individual SDH subunit genes. PGL type 1 is associated with germline mutations in the SDHD gene; the tumors are more likely multifocal and rarely malignant than in the other types. The locus for PGL type 2, reported in a large Dutch family, has recently been identified as SDH5, on 11q13.1 [2]. The very rare PGL type 3 is associated with mutations in SDHC, encoding subunit C of the SDH complex. PGL type 4 is associated with mutations in the SDHB gene, and these patients are at high risk for malignant disease [3e5]. Individuals with germline mutations in SDHB and SDHD may develop tumors along the whole paraganglia distribution area, and they may also be susceptible to pheochromocytoma (PHE) (i.e., intra-adrenal paraganglioma) [6]. The proband, a 13-year-old girl of Czech origin, demonstrated clinical indicators of PGL. She had refractory hypertension, sweating and headaches, and elevated catecholamine concentrations in plasma and urine (namely, norepinephrine). Computed tomography revealed an expansive mass, 35 30 35 mm) of uncertain etiology in the left para-aortic region (or inside the left suprarenal gland), and an extending mass, 38 45 50 mm, in the left superior posterior mediastinum region. At surgery, the para-aortic mass was excised and paraganglioma revealed by histology. One month after the first operation, a biopsy of the mediastinal tumor was made and the diagnosis of paraganglioma confirmed. Postoperative computed tomography, positron emission tomography, and magnetic resonance imaging demonstrated voluminous tumor

Hypophosphatasia due to uniparental disomy

Wehave readwith interest the paper byWatanabe et al. [1] describing a fetus with hypophosphatasia (HPP) caused by paternal uniparental disomy (UPD) of chromosome 1 resulting in homozygosity for an ALPLmutation. Although we have recently identified a similar case, we are not convinced that the claim by Watanabe et al. that UPD can be a frequent mechanism of recessive disorders is supported by current data. However, it should be stressed that UPD is not the only reason why parental genotypes should always be tested when homozygosity for a recessivemutation is identified in the child, especially in a prenatal diagnostic setting. Our patient was a male in whom skeletal dysplasia was suspected prenatally due to shortening of limbs visible on ultrasound in the 3rd trimester. He was born slightly pre-term (37th week of gestation), with body weight and length appropriate for the gestational age (2890 g, 49 cm). His postnatal adaptation was disturbed (Apgar score 6-7-7). The boy showed characteristics typical for perinatal HPP (shortening of long bones, softening of the skull bones, dyspnea, hypotonia and severe general hypomineralization of bones (Fig. 1)), unmeasurably low level of tissue-nonspecific alkaline phosphatase (b0.2 ukat/l) and hypercalcemia (3.04 mmol/l). The diagnosis of perinatal HPP was confirmed by the identification of a homozygous ALPL mutation NM_000478.4:c.1471G N A, p.G491R, which has already been described [2] and is considered to be pathogenic. The boywas included into a clinical study of enzyme replacement therapy at the age of 3 months and at the current age of 13 months his clinical response is very good. Surprisingly, the mutation identified in a homozygous status in the patient was heterozygous in the mother but absent in the father. To resolve this discrepancy, SNP array analysis was performed in the family using Illumina Human CytoSNP-12 BeadChips. Mixed maternal uniparental isodisomy (iUPD) and heterodisomy (hUPD) was identified in the patient affecting his whole chromosome 1, with a 35 Mb long segment of iUPD encompassing the ALPL gene (Fig. 2). While the paternal iUPD of the whole chromosome 1 observed by Watanabe et al. [1] was a likely result of monosomy rescue or of a post-fertilization error, the mixedmaternal iUPD andhUPDdetected in our patient pointed to trisomy rescue as the most likely scenario (or less likely to gamete complementation) [3]. A 68 Mb segment of iUPD around the centromere (Fig. 2) indicated non-disjunction in the second meiotic division,