Multi-gene panels are used to identify genetic causes of hereditary breast and ovarian cancer (HBOC) in large patient cohorts. This study compares the diagnostic workflow in two centers and gives ...valuable insights into different next-generation sequencing (NGS) strategies. Moreover, we present data from 620 patients sequenced at both centers. Both sequencing centers are part of the German consortium for hereditary breast and ovarian cancer (GC-HBOC). All 620 patients included in this study were selected following standard
BRCA1/
2 testing guidelines. A set of 10 sequenced genes was analyzed per patient. Twelve samples were exchanged and sequenced at both centers. NGS results were highly concordant in 12 exchanged samples (205/206 variants = 99.51 %). One non-pathogenic variant was missed at center B due to a sequencing gap (no technical coverage). The custom enrichment at center B was optimized during this study; for example, the average number of missing bases was reduced by a factor of four (vers. 1: 1939.41, vers. 4: 506.01 bp). There were no sequencing gaps at center A, but four CCDS exons were not included in the enrichment. Pathogenic mutations were found in 12.10 % (75/620) of all patients: 4.84 % (30/620) in
BRCA1
, 4.35 % in
BRCA2
(27/620), 0.97 % in
CHEK2
(6/620), 0.65 % in
ATM
(4/620), 0.48 % in
CDH1
(3/620), 0.32 % in
PALB2
(2/620), 0.32 % in
NBN
(2/620), and 0.16 % in
TP53
(1/620). NGS diagnostics for HBOC-related genes is robust, cost effective, and the method of choice for genetic testing in large cohorts. Adding 8 genes to standard
BRCA1
- and
BRCA2
-testing increased the mutation detection rate by one-third.
Interstitial deletions encompassing chromosome bands 1p32.1p32.3 are rare. Only nine unrelated patients with partially overlapping 1p32.1p32.3 deletions of variable size and position have been ...reported to date. We report on a 17-month-old boy with choanal atresia, hearing loss, urogenital anomalies, and microcephaly in whom an interstitial de novo deletion of 6.4 Mb was detected in 1p32.1p32.3 (genomic position chr1:54,668,618-61,113,264 according to GRCh37/hg19). The deleted region harbors 31 RefSeq genes. Notable genes in the region are PCSK9, haploinsufficiency of which caused low LDL cholesterol plasma levels in the patient, and DAB1, which is a candidate gene for cognitive deficits, microcephaly, and cerebral abnormalities such as ventriculomegaly and agenesis of the corpus callosum. Choanal atresia, microcephaly, and severe hearing loss were previously not known to be associated with 1p32 deletions. Our reported patient thus broadens the spectrum of clinical findings in this chromosome region and further facilitates genotype-phenotype correlations. Additional patients with overlapping deletions and/or point mutations in genes of this region need to be identified to elucidate the role of individual genes for the complex clinical manifestations.
Intellectual disability (ID) occurs in approximately 1% of the population. Over the last years, broad sequencing approaches such as whole exome sequencing (WES) substantially contributed to the ...definition of the molecular defects underlying nonsyndromic ID. Pathogenic variants in HIVEP2, which encodes the human immunodeficiency virus type I enhancer binding protein 2, have recently been reported as a cause of ID, developmental delay, behavioral disorders, and dysmorphic features. HIVEP2 serves as a transcriptional factor regulating NF-ĸB and diverse genes that are essential in neural development. To date, only 8 patients with pathogenic de novo nonsense or frameshift variants and 1 patient with a pathogenic missense variant in HIVEP2 have been reported. By WES, we identified 2 novel truncating HIVEP2 variants, c.6609_6616delTGAGGGTC (p.Glu2204*) and c.6667C>T (p.Arg2223*), in 2 young adults presenting with developmental delay and mild ID without any dysmorphic features, systemic malformations, or behavioral issues.
Isolated interstitial duplications of chromosome band 1q25 are apparently very rare; no patients with detailed molecular and clinical characterization of duplications restricted to this region have ...been published to date. We report on a 9-year-old girl with mild cognitive deficits, tall stature, macrocephaly and discrete dysmorphic features in whom a de novo interstitial 7.5 Mb duplication of 1q25.1q25.3 was detected by SNP array analysis (arrhg19 1q25.1q25.3(173,925,505-181,381,242)x3 dn). The duplicated region was inversely inserted into chromosome band 1q42.2: 46,XX,der(1)(pter→q42.2::q25.3→q25.1::q42.2→qter). Overexpression of one or several of the 87 genes in the duplicated interval was presumably the major causative factor for the clinical manifestations. Reports of additional patients with overlapping duplications will be needed to establish detailed karyotype-phenotype correlations and to gain a better understanding of the underlying pathomechanisms.
To investigate the postnatal development of cerebral perfusion in preterm neonates with normal brains over the first 2 wk of life, a prospective longitudinal study was designed. Quantitative ...measurement of cerebral blood flow (CBF) volume was performed using ultrasound flowmetry of the extracranial, brain-feeding arteries in 32 preterm infants of 28-35 wk gestational age. Measurements were done in the internal carotid and vertebral arteries of both sides on d 1, 2, 3, 7, and 14 after birth. A 10.0-MHz linear transducer of a computed sonography system (Acuson 128/XP10) was used. Intravascular flow volumes were calculated as the product of angle-corrected time-averaged flow velocity and the cross-sectional area of the vessel. Mean CBF volume increased markedly over the first 2 wk. One-third of this rise already occurred from the first to the second postnatal day, thereafter there was a continuous increase from d 2 to d 14 of life. Whereas the absolute level of CBF volume was primarily determined by postmenstrual age, the pattern of postnatal changes in CBF volume was found to be independent of gestational age. Arterial carbon dioxide tension, mean arterial blood pressure, and hematocrit had no influence on the development of CBF volume. The pronounced increase of CBF volume from d 1 to d 2 is likely to represent a normal adaptive response of the cerebral circulation to postnatal life. The data presented here may serve as the basis for further studies to investigate whether deviations from this adaptive response are associated with an increased risk of brain injury.
To assess whether middle cerebral artery (MCA) vasospasm reduces the flow volume in the corresponding extracranial internal carotid artery (ICA) or global cerebral blood flow volume (CBFV) in ...subarachnoid haemorrhage (SAH) patients, a colour duplex ultrasound study of the intra- and extracranial cerebral arteries was performed. MCA vasospasm was defined as a time-averaged maximum flow velocity (TAMX) exceeding 120 cm/s. ICA flow volumes and CBFV, were compared in each patient at maximum TAMX recorded in one MCA ("maximum-vasospasm") and when TAMX in the same vessel was closest to mean reference values ("no-vasospasm"). Additionally, the CBFV course during the first 3 weeks after SAH was evaluated longitudinally. Data from age- and gender-matched healthy test persons served as control. In 28 patients with MCA vasospasm, 337 measurements were completed. Global CBFV was significantly reduced starting from day 3 after SAH. ICA flow volumes and CBFV were not different when comparing at "maximum-vasospasm" and "no-vasospasm". Compared with the control group, both were lower at either condition. Thus, in SAH patients, vasospasm even severe, in general does not further diminish ICA flow volumes and global CBFV, which are reduced already before the onset of vasospasm.
Deletions of chromosome band 12q24.33 are rare. We report on a 17-year-old male patient with intellectual disability but no major malformations or dysmorphic features in whom a de novo interstitial ...660 kb deletion in 12q24.33 was detected by SNP array analysis. This deletion was secondary to a translocation t(12;14)(q24.3;q13)dn that also led to a small deletion in 14q21.1 and a small duplication in 2p23.1. The deletion overlaps with two previously published larger deletions in patients who suffered from intellectual disability, obesity, and polycystic kidney disease, indicating that haploinsufficiency of one or several of the genes in the deleted interval of the patient reported here causes intellectual deficits, but not obesity or renal problems. The 14 RefSeq genes that are harbored by this deletion include P2RX2, which had previously been proposed as a candidate gene for intellectual disability. Thus, the patient reported here broadens our knowledge of the phenotypic consequences of deletions in 12q24.33 and facilitates genotype-phenotype correlations for chromosome aberrations of this region.
Cerebral blood flow (CBF) volume can be measured quantitatively by colour duplex sonography. To test the reliability of CBF volume measurements in newborns, two "blinded" examiners performed a ...prospective test-retest study in 32 neonates (postmenstrual age 32 to 42 weeks). Measurements were done in the internal carotid and vertebral arteries. Intravascular flow volumes (FV) were calculated as the product of angle-corrected time-averaged flow velocity and the cross-sectional area of the vessel. The CBF volumes measured by the two examiners were very close (mean +/- SD, 62.6 +/- 20.6 vs. 62.1 +/- 21.2 mL/min, NS; coefficient of variation, 6.3%; intraclass correlation coefficient, 0.98). The 95% limits of agreement, according to Bland and Altman, ranged from -7.3 to +8.4 mL/min. In comparison with other test-retest studies, the reproducibility of quantitative CBF measurements reported here is among the best ever found. We conclude that CBF volume can be measured reliably even in preterm neonates.
Increased echogenicity of the substantia nigra (SN) on transcranial ultrasonography (TCS) is a typical sign in Parkinson's disease (PD). Detected in healthy adults it is assumed to represent a risk ...factor for nigral injury. We studied at which time point of brain maturation increased signal intensity may occur by performing TCS scans in 109 newborns and children aged 0-192 months. While newborns regularly exhibit SN hyperechogenicity, this echofeature decreases substantially during the first years of life. As SN echogenicity is related to the tissue iron content in adults our findings suggest a failure in SN iron metabolism in some children with increased echogenicity during development which can be disclosed by TCS.
To investigate the development of cerebral haemodynamics in healthy preterm and term newborns, a prospective colour duplex sonography study was performed in 113 neonates at 32 to 42 weeks of ...postmenstrual age. In the extracranial internal carotid arteries (ICAs) and vertebral arteries (VAs), luminal diameters and angle-corrected flow velocities were measured. Flow volumes and waveform parameters were calculated. There were no side-to-side or gender-related differences for any of the parameters measured. A marked increase of luminal diameters, end-diastolic and time-averaged flow velocities and flow volumes with postmenstrual age was found in both ICA and VA (
p ≤ 0.0001). Peak systolic velocity did not vary with age, thus, leading to a significant decrease of the resistance and pulsatility indices with rising postmenstrual age. Reference data for flow velocities, waveform parameters, luminal diameters and flow volumes of both ICA and VA are provided for different groups of postmenstrual age. In conclusion, the marked increase in cerebral blood flow volume with postmenstrual age is due to a rise in the luminal diameter of extracranial cerebral arteries and a decrease in peripheral vascular resistance. (E-mail:
martin.schoening@med.uni-tuebingen.de)
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