Haploinsufficiency of PRR12 causes a spectrum of neurodevelopmental, eye, and multisystem abnormalities.

PURPOSE: Proline Rich 12 (PRR12) is a gene of unknown function with suspected DNA-binding activity, expressed in developing mice and human brains. Predicted loss-of-function variants in this gene are extremely rare, indicating high intolerance of haploinsufficiency. METHODS: Three individuals with intellectual disability and iris anomalies and truncating de novo PRR12 variants were described previously. We add 21 individuals with similar PRR12 variants identified via matchmaking platforms, bringing the total number to 24. RESULTS: We observed 12 frameshift, 6 nonsense, 1 splice-site, and 2 missense variants and one patient with a gross deletion involving PRR12. Three individuals had additional genetic findings, possibly confounding the phenotype. All patients had developmental impairment. Variable structural eye defects were observed in 12/24 individuals (50%) including anophthalmia, microphthalmia, colobomas, optic nerve and iris abnormalities. Additional common features included hypotonia (61%), heart defects (52%), growth failure (54%), and kidney anomalies (35%). PrediXcan analysis showed that phecodes most strongly associated with reduced predicted PRR12 expression were enriched for eye- (7/30) and kidney- (4/30) phenotypes, such as wet macular degeneration and chronic kidney disease. CONCLUSION: These findings support PRR12 haploinsufficiency as a cause for a novel disorder with a wide clinical spectrum marked chiefly by neurodevelopmental and eye abnormalities.

Age Dependent Progression of Multiple Epiphyseal Dysplasia and Pseudoachondroplasia Due to Heterozygous Mutations in COMP Gene.

Dominantly inherited mutations in COMP gene encoding cartilage oligomeric matrix protein may cause two dwarfing skeletal dysplasias, milder multiple epiphyseal dysplasia (MED) and more severe pseudoachondroplasia (PSACH). We studied the phenotype and X-rays of 11 patients from 5 unrelated families with different COMP mutations. Whole exome and/or Sangers sequencing were used for molecular analyses. Four to ten X-ray images of hands hips, knees or spine were available for each patient for retrospective analyses. Eight patients with MED have mutation c.1220G>A and 3 children with PSACH mutations c.1359C>A, c.1336G>A, or the novel mutation c.1126G>T in COMP. Progressive failure in growth developed in all patients from early childhood and resulted in short stature < 3rd percentile in 7 patients and very short stature < 1st percentile in four. Most patients had joint pain since childhood, severe stiffness in shoulders and elbows but increased mobility in wrists. Six children had bowlegs and two had knock knees. In all patients, X-rays of hands, hips and knees showed progressive, age-dependent skeletal involvement more pronounced in the epiphyses of long rather than short tubular bones. Anterior elongation and biconvex configuration of vertebral bodies were more conspicuous for kids. Six children had correction of knees and two adults had hip replacement. Skeletal and joint impairment in patients with MED and PSACH due to COMP mutation start in early childhood. Although the clinical severity is mutation and age dependent, many symptoms represent a continuous phenotypic spectrum between both diseases. Most patients may benefit from orthopaedic surgeries.

Attenuated Type of Asphyxiating Thoracic Dysplasia due to Mutations in DYNC2H1 Gene.

Asphyxiating thoracic dysplasia (ATD) represents a heterogeneous group of skeletal dysplasias with short ribs, narrow chest and reduced thoracic capacity. Mutations in several genes including IFT80, DYNC2H1, TTC21B and WDR19 have been found in patients with ATD. Both severe and milder course of the disease were described in correlation with secondary involvement of lung's function. Two children with attenuated form of ATD are described. Their anthropometric parameters for birth weight, length and head circumference were normal but narrow thorax was observed in both of them in early infancy with chest circumference < -3 SD (standard deviation) in comparison to age related controls. The postnatal adaptation and development of both children was uneventful except for mild tachypnoea in one of them which persisted till the age of 6 months. In both children, radiographs revealed narrow upper half of the chest with shorter ribs and atypical configuration of pelvis with horizontally running acetabula and coarse internal edges typical for ATD. Molecular analyses using whole exome sequencing in one family revealed that the patient is compound heterozygote in DYNC2H1 gene for a frame-shift mutation c.4458delT resulting in premature stop-codon p.Phe1486Leufs*11 and a missense mutation c.9044A>G (p.Asp3015Gly). The second family refused the DNA analysis. Regular monitoring of anthropometric parameters during childhood is of big importance both in health and disease. In addition, measurement of the chest circumference should be included, at least at birth and during infancy.

The Age Dependent Progression of Hajdu-Cheney Syndrome in Two Families.

Hajdu-Cheney syndrome (HCS) is a rare multi-system disease with autosomal dominant inheritance and skeletal involvement, resulting mostly in craniofacial dysmorphy with mid-face hypoplasia, dental anomalies, short stature, scoliosis, shortening of the digits and nail beds, acro-osteolysis and osteoporosis. We report the progression of clinical and radiographic findings in five patients with Hajdu-Cheney syndrome from two families. A custom capture array designed to capture exons and adjacent intron sequences of 230 selected genes were used for molecular analyses, and the pathogenic variants identified were confirmed by PCR and Sanger sequencing. In both families we observed age-dependent changes in the disease, with a progression of pain in older patients, a shortening of digits and nail beds on both the hands and feet, kyphoscoliosis and the persistence of Wormian bones in lambdoid sutures. Molecular analyses performed in two patients revealed that they are heterozygotes for a c.6255T>A (p.Cys2085*) variant in the NOTCH2 gene, resulting in a premature stop-codon. Bone mineral density (Z-score < -2) did not improved in a girl treated with calcium and vitamin D supplementation during childhood and bisphosphonate during adolescence. Hajdu-Cheney syndrome is a slowly progressive disease with a frequently unfavourable prognosis in elderly patients, especially for the development of dental anomalies, osteoporosis and the progression of skeletal complications requiring orthopedic surgeries.

Mutations in ANTXR1 cause GAPO syndrome.

The genetic cause of GAPO syndrome, a condition characterized by growth retardation, alopecia, pseudoanodontia, and progressive visual impairment, has not previously been identified. We studied four ethnically unrelated affected individuals and identified homozygous nonsense mutations (c.262C>T [p.Arg88*] and c.505C>T [p.Arg169*]) or splicing mutations (c.1435-12A>G [p.Gly479Phefs*119]) in ANTXR1, which encodes anthrax toxin receptor 1. The nonsense mutations predictably trigger nonsense-mediated mRNA decay, resulting in the loss of ANTXR1. The transcript with the splicing mutation theoretically encodes a truncated ANTXR1 containing a neopeptide composed of 118 unique amino acids in its C terminus. GAPO syndrome's major phenotypic features, which include dental abnormalities and the accumulation of extracellular matrix, recapitulate those found in Antxr1-mutant mice and point toward an underlying defect in extracellular-matrix regulation. Thus, we propose that mutations affecting ANTXR1 function are responsible for this disease's characteristic generalized defect in extracellular-matrix homeostasis.

Novel FBN1 gene mutation and maternal germinal mosaicism as the cause of neonatal form of Marfan syndrome.

Marfan syndrome (MFS) is an autosomal dominant disorder caused by mutations in the fibrillin 1 gene (FBN1). Neonatal form of MFS is rare and is associated with severe phenotype and a poor prognosis. We report on a newborn girl with neonatal MFS who displayed cyanosis and dyspnea on the first day of life. The main clinical features included mitral and tricuspid valve insufficiency, aortic root dilatation, arachnodactyly, and loose skin. Despite the presence of severe and inoperable heart anomalies, the girl was quite stable on symptomatic treatment and lived up to the 7th month of age when she died due to cardiorespiratory failure. Molecular-genetic studies revealed a novel intronic c.4211-32_-13del mutation in the FBN1 gene. Subsequent in vitro splicing analysis showed this mutation led to exon 35 skipping, presumably resulting in a deletion of 42 amino acids (p.Leu1405_Asp1446del). Interestingly, this mutation is localized outside the region of exons 24-32, whose mutation is responsible for the substantial majority of cases of neonatal MFS. Although the family history of MFS was negative, the subsequent molecular genetic examination documented a mosaicism of the same mutation in the maternal blood cells (10-25% of genomic DNA) and the detailed clinical examination showed unilateral lens ectopy.

Is it always possible to determine a diagnosis? Prenatal ultrasonography, post mortem magnetic resonance, autopsy.

Pathological-anatomical autopsy is the gold standard for determining of foetal abnormalities, but in some cases its role is limited (pathology of central nervous system, in particular, in case of ventricular dilatation or developed autolysis). In pathology of central nervous system, where insufficiency of autopsy can occur, additional post mortem magnetic resonance imaging (MRI) is performed to determine type of malformation. In this case report, we would like to point out the fact that although all investigating methods including post mortem magnetic resonance and autopsy (incl. imunohistochemical tests) are used, this need not necessarily result in a clear diagnostic conclusion of the aborted foetus. Post mortem MRI visualized pathology: dilatation of both lateral ventricals, more in the left and, above all, a pathological focus parasagittaly on the right with haemorrhage and cystic component; it raised a suspicion on ependymoma. However imunohistochemical test did not give an unambiguous conclusion; therefore diagnosis based on MRI could not be uniquely verified.

Mutation analysis of TRPS1 gene including core promoter, 5'UTR, and 3'UTR regulatory sequences with insight into their organization.

The TRPS1 protein is a potent regulator of proliferation, differentiation, and apoptosis. The TRPS1 gene aberrations are strongly associated with rare trichorhinophalangeal syndrome (TRPS) development. We have conducted MLPA analysis to capture deletion within the crucial 8q24.1 chromosomal region in combination with mutation analysis of TRPS1 gene including core promoter, 5'UTR, and 3'UTR sequences in nine TRPS patients. Low complexity or extent of untranslated regulatory sequences avoided them from analysis in previous studies. Amplicon based next generation sequencing used in our study bridge over these technical limitations. Finally, we have made extended in silico analysis of TRPS1 gene regulatory sequences organization. Single contiguous deletion and an intragenic deletion intervening several exons were detected. Mutation analysis revealed five TRPS1 gene aberrations (two structural rearrangements, two nonsense mutations, and one missense substitution) reaching the overall detection rate of 78%. Several polymorphic variants were detected within the analysed regulatory sequences but without proposed pathogenic effect. In silico analysis suggested alternative promoter usage and diverse expression effectivity for different TRPS1 transcripts. Haploinsufficiency of TRPS1 gene was responsible for most of the TRPS phenotype. Structure of TRPS1 gene regulatory sequences is indicative of generally low single allele expression and its tight control.

Genetic variations in NADPH-CYP450 oxidoreductase in a Czech Slavic cohort.

AIM: Estimating polymorphic allele frequencies of the NADPH-CYP450 oxidoreductase (POR) gene in a Czech Slavic population. METHODS: The POR gene was analyzed in 322 individuals from a control cohort by sequencing and high resolution melting analysis. RESULTS: We identified seven unreported SNP genetic variations, including two SNPs in the 5' flanking region (g.4965C>T and g.4994G>T), one intronic variant (c.1899-20C>T), one synonymous SNP (p.20Ala=) and three nonsynonymous SNPs (p.Thr29Ser, p.Pro384Leu and p.Thr529Met). The p.Pro384Leu variant exhibited reduced enzymatic activities compared with wild-type. CONCLUSION: New POR variant identification indicates the number of uncommon variants might be specific for each subpopulation being investigated, particularly germane to the singular role that POR plays in providing reducing equivalents to all CYP450s in the endoplasmic reticulum. Original submitted 15 September 2014; Revision submitted 17 November 2014.

Cryptic chromosomal rearrangements in children with idiopathic mental retardation in the Czech population.

AIMS: The aim of our study was to scan for cryptic rearrangements using the multiplex ligation probe amplification method in a cohort of 64 probands with mental retardation or developmental delays in combination with at least one of the following symptoms: hypotonia after birth, congenital anomalies, or face dysmorphisms; but without a positive cytogenetic finding. The study contributes to the knowledge of microdeletion syndromes and helps disclose their natural phenotypic variability. RESULTS: In total, 10 positives (16%) were detected, particularly 3 duplications (Xpter-p22.32; 17p11.2; 22q11) and 6 different deletions (1p36; 7q11.23; 10p15; 15q11-q13; 17p11.2; 17p13.3), 1 of these in 2 probands. Besides the well-characterized syndromes, less-often described rearrangements with ambiguous phenotype associations were also detected. CONCLUSIONS: Some rearrangements, particularly duplications, are associated with vague phenotypes; and their frequency could be underestimated.

APOE epsilon4: a potential modulation factor in Rett syndrome.

Rett syndrome is a neurodevelopmental disorder mainly caused by de novo mutations in the MECP2 (methyl-CpG-binding protein 2) gene. There is considerable variation in the severity of clinical features among Rett syndrome patients, even among patients with the same MECP2 mutation. In addition to X-chromosome inactivation pattern, the genetic background of the affected individual might also have a role in determining the severity of the disorder. We suggest that APOE is one of the genetic modulating factors. We analyzed clinical phenotypes of 46 patients with Rett syndrome, with confirmed MECP2 mutation. We discovered that among epsilon4 carriers, some clinical features were more severe, and the developmental regression occurred 4 months earlier on average than in those without the epsilon4 allele. Earlier onset of regression suggests a possible trend; however, it did not achieve distinctive statistical significance. Nevertheless, the epsilon4 allele of APOE may serve as a candidate modulation factor for the Rett syndrome phenotype.

Post-mortem magnetic resonance imaging and its irreplaceable role in determining CNS malformation (hydranencephaly)--case report.

Post-mortem magnetic resonance appears to be a method supplementary to classic pathological-anatomical autopsy in determining foetal abnormalities. Frequently, it plays a key role, primarily where autopsy options are in some way limited (developed autolysis, dilatation of the ventricular system). This case report demonstrates that post-mortem magnetic resonance imaging can precisely determine the type of congenital malformation (hydranencephaly), by contrast to ultrasound, with which alobar holoprosencephaly has been described, often presenting a differential diagnosis problem. Pathological-anatomical autopsy was significantly limited due to this diagnosis and this methodology was incapable of unequivocally determining the type of malformation. We would like to demonstrate by this case report the necessity of performing post-mortem magnetic resonance imaging so that we may precisely determine the diagnosis as requested by the parents and also be able to answer the question posed by risks for future pregnancies.

Mutation analysis of the MECP2 gene in patients of Slavic origin with Rett syndrome: novel mutations and polymorphisms.

Rett syndrome (RTT), an X-linked dominant neurodevelopmental disorder in females, is caused mainly by de novo mutations in the methyl-CpG-binding protein 2 gene (MECP2). Here we report mutation analysis of the MECP2 gene in 87 patients with RTT from the Czech and Slovak Republics, and Ukraine. The patients, all girls, with classical RTT were investigated for mutations using bi-directional DNA sequencing and conformation sensitive gel electrophoresis analysis of the coding sequence and exon/intron boundaries of the MECP2 gene. Restriction fragment length polymorphism analysis was performed to confirm the mutations that cause the creation or abolition of the restriction site. Mutation-negative cases were subsequently examined by multiple ligation-dependent probe amplification (MLPA) to identify large deletions. Mutation screening revealed 31 different mutations in 68 patients and 12 non-pathogenic polymorphisms. Six mutations have not been previously published: two point mutations (323T>A, 904C>T), three deletions (189_190delGA, 816_832del17, 1069delAGC) and one deletion/inversion (1063_1236del174;1189_1231inv43). MLPA analysis revealed large deletions in two patients. The detection rate was 78.16%. Our results confirm the high frequency of MECP2 mutations in females with RTT and provide data concerning the mutation heterogeneity in the Slavic population.