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Objective: Most genetic disorders, especially rare and manifested with an unspecific constellation of developmental anomalies, are challenging to diagnose before birth. The paper aims to present a rare case of terminal 21q22 deletion to extend the knowledge on this rare genetic disease, mostly to facilitate prenatal guidance by pointing the diagnostic features., Case Report: The fetus was diagnosed prenatally, at 21 weeks of gestation, due to ultrasound markers detected in a routine ultrasound scan. Post-mortem dysmorphological assessment has verified the diagnosis. To the best of our knowledge, this is the second report of prenatal presentation of partial monosomy 21q., Conclusion: By giving the detailed phenotype description and presenting a comprehensive literature review on the subject, we delineate its phenotype, which was different from what has been shown in the literature. Specifically, the clinical presentation of aberration within regions 2 and 3 (referring to the term proposed by Lyle et al., in 2009) of 21q22 bands is not characterised by multiple or severe malformations, which matters for prenatal counselling and diagnostics., Competing Interests: Declaration of competing interest All authors declare no conflict of interest., (Copyright © 2021. Published by Elsevier B.V.)

Purpose: Pathogenic variants in ARID1B are one of the most frequent causes of intellectual disability (ID) as determined by large-scale exome sequencing studies. Most studies published thus far describe clinically diagnosed Coffin-Siris patients (ARID1B-CSS) and it is unclear whether these data are representative for patients identified through sequencing of unbiased ID cohorts (ARID1B-ID). We therefore sought to determine genotypic and phenotypic differences between ARID1B-ID and ARID1B-CSS. In parallel, we investigated the effect of different methods of phenotype reporting., Methods: Clinicians entered clinical data in an extensive web-based survey., Results: 79 ARID1B-CSS and 64 ARID1B-ID patients were included. CSS-associated dysmorphic features, such as thick eyebrows, long eyelashes, thick alae nasi, long and/or broad philtrum, small nails and small or absent fifth distal phalanx and hypertrichosis, were observed significantly more often (p < 0.001) in ARID1B-CSS patients. No other significant differences were identified., Conclusion: There are only minor differences between ARID1B-ID and ARID1B-CSS patients. ARID1B-related disorders seem to consist of a spectrum, and patients should be managed similarly. We demonstrated that data collection methods without an explicit option to report the absence of a feature (such as most Human Phenotype Ontology-based methods) tended to underestimate gene-related features.

The urea cycle disorder carbamoyl phosphate synthetase I deficiency is an important differential diagnosis in the encephalopathic neonate. This intoxication type inborn error of metabolism often leads to neonatal death or severe and irreversible damage of the central nervous system, even despite appropriate treatment. Timely diagnosis is crucial, but can be difficult on routine metabolite level. Here, we report ten neonates from eight families (finally) diagnosed with CPS1 deficiency at three tertiary metabolic centres. In seven of them the laboratory findings were dominated by significantly elevated urinary 3-methylglutaconic acid levels which complicated the diagnostic process. Our findings are both important for the differential diagnosis of patients with urea cycle disorders and also broaden the differential diagnosis of hyperammonemia associated with 3-methylglutaconic aciduria, which was earlier only reported in TMEM70 and SERAC1 defect., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Cardio-facio-cutaneous (CFC) syndrome is characterized by a variable degree of developmental delay and congenital anomalies, including characteristic facial, cardiac, and ectodermal abnormalities. It is caused by activating mutations in the Ras/mitogen-activated protein kinase (MAPK) signaling pathway. In, however, approximately 10%-30% of individuals with a clinical diagnosis of CFCS, no mutation of the causative gene is found. Therefore, clinical studies in patients with the CFCS spectrum are valuable. To investigate the phenotypic spectrum and molecular diversity of germline mutations affecting genes encoding serine/threonine kinases, a group of 15 children and young adults with a diagnosis of CFCS was screened. We documented three novel mutations in the BRAF gene and correlated clinical findings with causative mutations in the BRAF or MEK1/MEK2 genes., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

Coffin-Lowry syndrome (CLS) is an X-linked semi-dominant disorder caused by mutations in the RSK2 gene and characterized by moderate to severe mental retardation, characteristic facial features, skeletal deformities, and tapering fingers in males. Females are usually much more mildly and variably affected thus more difficult to diagnose. In this study, molecular genetic analysis was carried out in four female patients presenting features of Coffin-Lowry syndrome. The probands were sporadic cases with no affected males in their families. The molecular analysis of the RSK2 gene revealed four novel mutations, including two frameshift and one missense mutation identified by sequencing, and one large deletion detected by multiplex ligation-dependent probe amplification (MLPA) analysis. Females exhibited a random X-chromosome inactivation pattern. To our knowledge, this is the first report of applying MLPA in the diagnostics of CLS and the first description of a large deletion in a CLS female. These results support including screening for large rearragements in the genetic analysis of female CLS patients., (Copyright © 2010 Elsevier Masson SAS. All rights reserved.)

The Nijmegen breakage syndrome (NBS) is a rare inherited condition, characterized by microcephaly, radiation hypersensitivity, chromosomal instability, an increased incidence of (mostly) lymphoid malignancies, and immunodeficiency. NBS is caused by hypomorphic mutations in the NBN gene (8q21). The NBN protein is a subunit of the MRN (Mre11-Rad50-NBN) nuclear protein complex, which associates with double-strand breaks. The immunodeficiency in NBS patients can partly be explained by strongly reduced absolute numbers of B lymphocytes and T lymphocytes. We show that NBS patients have a disturbed precursor B-cell differentiation pattern and significant disturbances in the resolution of recombination activating gene-induced IGH breaks. However, the composition of the junctional regions as well as the gene segment usage of the reduced number of successful immunoglobulin gene rearrangements were highly similar to healthy controls. This indicates that the NBN defect leads to a quantitative defect in V(D)J recombination through loss of juxtaposition of recombination activating gene-induced DNA ends. The resulting reduction in bone marrow B-cell efflux appeared to be partly compensated by significantly increased proliferation of mature B cells. Based on these observations, we conclude that the quantitative defect will affect the B-cell receptor repertoire, thus contributing to the observed immunodeficiency in NBS patients.

Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive disorder caused by reduced activity of 7-dehydrocholesterol reductase, resulting in an increased concentrations of 7-dehydrocholesterol and 8-dehydrocholesterol in body fluids and tissues. Phenotypically it is characterized by wide range of abnormalities, from mild to lethal forms what causes difficulties in its clinical diagnostics. To further delineate the physical spectrum of the mild form of Smith-Lemli-Opitz syndrome, especially with regard to genotype-phenotype correlation, we describe 5 Polish patients with mild phenotype (one with novel mutation in DHCR7 gene and four published before) and analyze 18 other cases from the literature. As the conclusion we give recommendation for tests toward SLOS in cases with "idiopathic" intellectual impairment and/or behavioral anomalies, as well as in biochemically doubtful but clinically fitting cases with overall gestalt and history of this syndrome.

Angelman syndrome (AS) is a neurodevelopmental disorder caused by failure of expression of the maternal copy of the imprinted UBE3A gene through a variety of mechanisms detected by methylation studies, mutation analysis of UBE3A and FISH. In 10-15% of suspected cases of AS these investigations do not reveal a genetic abnormality. We report here the development of a semi-quantitative dosage PCR technique used to identify sub-microscopic deletions involving UBE3A. Using this method we analysed a panel of 26 patients from 24 families, all fulfilling the clinical criteria for AS. We identified a deletion of UBE3A exons 8-16 in a sibling pair. Analysis of parental samples revealed the same deletion in their phenotypically normal mother. This is an inexpensive and valuable method for detecting UBE3A deletions in a small but important proportion of AS cases of unidentifiable cause.

Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive disorder of cholesterol biosynthesis caused by mutations in the DHCR7 gene. Previous studies estimated the prevalence of SLOS between 1 in 10,000 to 1 in 70,358 based on case frequency surveys. Although panethnic, SLOS appears to be most frequent in Central European populations (Czech Republic 1 in 10,000, Slovakia 1 in 15,000 - 1 in 20,000). In Polish individuals with SLOS two DHCR7 mutations, c.452G>A (p.Trp151X) and c.976G>T (p.Val326Leu), account for 65.2% of all observed DHCR7 mutations. We analyzed 2169 samples for the p.Trp151X mutation and 2087 for the p.Val326Leu mutation. The combined carrier frequency of these two mutations of was 2.40+/-0.32%, yielding a calculated incidence of SLOS in Poland of 2.5 4x10(-4)-4.3 5x10(-4) (1 in 2,300 to 1 in 3,937) placing SLOS among the most common recessive genetic disorders in Poland.

The risk of offspring with unbalanced karyotypes born to carriers of reciprocal chromosomal translocation (RCT) is important to evaluate for further family planning and prenatal diagnosis. The authors describe two families with carriers of similar RCT concerning breakpoint positions and discuss the different individual risks for abnormal progeny. These translocations were studied by GTG, RBG and CBG banding. They have the same breakpoint on 9p, i.e. 9p22, and a different one on 12p, i.e. terminal (pter----p13) and intermediate (p11.2), respectively. The risk value of 27% for family 1 was obtained directly from the large enough pedigree (high risk) a risk value of about 5% was estimated for family 2, according to the guidelines of Stene and Stengel-Rutkowski (1988). The data show that similar translocations with only slight differences in the breakpoints position have different risks for unbalanced progeny. Results of these empiric findings may be used directly in genetic counselling of a family with RCT leading to a single imbalance of the same segment.