Breast density in NF1 women: a retrospective study.

Neurofibromatosis type 1 (NF1) is an autosomal dominant condition caused by neurofibromin haploinsufficiency due to pathogenic variants in the NF1 gene. Tumor predisposition has long been associated with NF1, and an increased breast cancer (BC) incidence and reduced survival have been reported in recent years for women with NF1. As breast density is another known independent risk factor for BC, this study aims to evaluate the variability of breast density in patients with NF1 compared to the general population. Mammograms from 98 NF1 women affected by NF1, and enrolled onto our monocentric BC screening program, were compared with those from 300 healthy subjects to verify differences in breast density. Mammograms were independently reviewed and scored by a radiologist and using a Computer-Aided Detection (CAD) software. The comparison of breast density between NF1 patients and controls was performed through Chi-squared test and with multivariable ordinal logistic models adjusted for age, body mass index (BMI), number of pregnancies, and menopausal status.breast density was influenced by BMI and menopausal status in both NF1 patients and healthy subjects. No difference in breast density was observed between NF1 patients and the healthy female population, even after considering the potential confounding factors.Although NF1 and a highly fibroglandular breast are known risk factors of BC, in this study, NF1 patients were shown to have comparable breast density to healthy subjects. The presence of pathogenic variants in the NF1 gene does not influence the breast density value.

Nasopharyngeal teratoma and diaphragmatic hernia: a non random association?

We describe a female affected by diaphragmatic hernia and nasopharyngeal teratoma. The case is compared with one already reported and possible diagnoses discussed. These cases appear to represent a new syndrome.

FISH characterization of a supernumerary r(1)(::cen-->q22::q22-->sq21::) chromosome associated with multiple anomalies and bilateral cataracts.

We describe the case of a 15-year-old girl with multiple congenital anomalies, dysmorphic features, severe kyphoscoliosis, growth and mental retardation, and the absence of speech, in whom 35% of the cells carried a supernumerary ring chromosome 1. Fluorescence in situ hybridization (FISH) analysis using YAC/BAC clones spanning the region from 1p13 to 1q21 made it possible to determine the genomic content and structure of the ring(1), which was found to consist of the cytogenetic bands 1q21-22. A complex structure was delineated in the ring chromosome with a partial inverted duplication delimited by markers WI-7732 and WI-607, with WI-7396 and WI-8386 being the boundaries of the single copy segment. Comparison of the clinical signs of other patients with mosaic r(1) reported in the literature allowed the identification of a patient sharing a number of clinical signs including cataracts. Given that mutations of the GJA8 gene encoding connexin 50 (Cx50) and mapping to 1q21 have been associated with the presence of cataracts, it is possible that a gain in copy number or a rearrangement of GJA8 may contribute to cataractogenesis.

Refined FISH characterization of a de novo 1p22-p36.2 paracentric inversion and associated 1p21-22 deletion in a patient with signs of 1p36 microdeletion syndrome.

We report on a 10-year-old boy presenting with obesity, moderate mental retardation, large anterior fontanelle at birth, mild physical anomalies including mid-face hypoplasia, deep-set eyes, long philtrum, and small mouth. He was found to carry a paracentric inversion inv(1)(p22p36.2) associated with a 10 cM deletion at the proximal breakpoint. By YAC FISH, the boundaries of the deletion were established at IB1028 (1p21) and WI-5166 (1p22) STSs contained in YACs 781E8 and 954F6, respectively. This large region, covering about 10 cM, contains the COL11A1 and AMY2B genes, whose haploinsufficiency does not seem to contribute significantly to the clinical phenotype. On the other hand, the patient's clinical manifestations, also including visual problems and moderate mental retardation, are those typically observed in the 1p36 deletion syndrome. Refined mapping of the telomeric 1p36.2 inversion breakpoint was obtained by FISH of a PAC contig constructed to encompass this subinterval of the 1p36 microdeletion syndrome region. PACs 1024B10 and 884E7 were found to span the breakpoint, suggesting that the clinical signs of the 1p36 microdeletion syndrome might be due to disruption of a sequence lying at 1p36.2.

Maternal chromosome 7 hetero/isodisomy in Silver-Russell syndrome and PEG1 biallelic expression.

Silver-Russell syndrome (SRS) is characterized by a severe intrauterine and postnatal growth retardation, relative macrocephaly associated with 'mild' facial anomalies. The diagnostic importance of skeletal asymmetry remains controversial. The aetiology of the syndrome is heterogeneous. Maternal uniparental disomy of chromosome 7 (mUPD7) has been reported in approximately 7% of patients, but two carriers of chromosomal abnormalities involving the band 17q25 have also been described. We investigated a clinically selected sample of 20 SRS patients for the presence of mUPD7 using polymorphic microsatellite markers spanning the whole chromosome. Maternal UPD7 was found in only one patient corresponding to an incidence of 5%. The allelic distribution in this patient was consistent with heterodisomy. Segregation analysis of chromosome 14 and 16 showed a biparental contribution in all the 20 patients. Blood RNA from the mUPD7 patient and a normal donor were evaluated for the expression of Paternally Expressed Gene (PEG1), an imprinted gene on chromosome 7q32. Biallelic expression of the gene in adult blood tissues was found in both samples. Our results confirm the causal role of mUPD7 in a minority of SRS patients.

NF1 microdeletion syndrome: refined FISH characterization of sporadic and familial deletions with locus-specific probes.

Two familial and seven sporadic patients with neurofibromatosis 1-who showed dysmorphism, learning disabilities/mental retardation, and additional signs and carried deletions of the NF1 gene-were investigated by use of a two-step FISH approach to characterize the deletions. With FISH of YAC clones belonging to a 7-Mb 17q11.2 contig, we estimated the extension of all of the deletions and identified the genomic regions harboring the breakpoints. Mosaicism accounted for the mild phenotype in two patients. In subsequent FISH experiments, performed with locus-specific probes generated from the same YACs by means of a novel procedure, we identified the smallest region of overlapping (SRO), mapped the deletion breakpoints, and identified the genes that map to each deletion interval. From centromere to telomere, the approximately 0.8-Mb SRO includes sequence-tagged site 64381, the SUPT6H gene (encoding a transcription factor involved in chromatin structure), and NF1. Extending telomerically from the SRO, two additional genes-BLMH, encoding a hydrolase involved in bleomycin resistance, and ACCN1, encoding an amiloride-sensitive cation channel expressed in the CNS-were located in the deleted intervals of seven and three patients, respectively. An apparently common centromeric deletion breakpoint was shared by all of the patients, whereas a different telomeric breakpoint defined a deletion interval of 0.8-3 Mb. There was no apparent correlation between the extent of the deletion and the phenotype. This characterization of gross NF1 deletions provides the premise for addressing correctly any genotype-phenotype correlation in the subset of patients with NF1 deletions.

Patient with large 17p11.2 deletion presenting with Smith-Magenis syndrome and Joubert syndrome phenotype.

We report on a 22-year-old woman carrying a del(17)(p11.2p12) and presenting with the clinical manifestations of both Smith-Magenis syndrome (SMS) and Joubert syndrome (JS). Her facial anomalies, brachydactyly, severe mental retardation, and self-injuring behavior could be attributed to SMS, whereas the cerebellar vermis hypoplasia, hypotonia, ataxic gait, developmental delay, and abnormal respiratory pattern were suggestive of JS. By fluorescent in situ hybridization analyses with Yeast Artificial Chromosomes (YAC) mapping to the 17p11.2 region, as well as locus-specific probes generated through a novel procedure, we could establish that the deletion encompasses a 4-Mb interval with centromeric and telomeric breakpoints at loci D17S793 and D17S953, the latter close to the locus Charcot Marie Tooth 1A (CMT1A)-REP. The deletion differs from that commonly found in SMS in its telomeric boundary, which is more distal than usually observed. The presence of JS phenotype in our patient and the detection of an unusual SMS deletion might suggest the presence of a JS gene in close proximity to the SMS locus.

New case of the Richieri-Costa/Guion-Almeida syndrome.

We describe a boy with multiple congenital anomalies/mental retardation (MCA/MR) syndrome. He has growth retardation, microbrachycephaly, coloboma of the iris, and typical facial anomalies including cleft lip/palate. This phenotype overlaps with that described by Richieri-Costa and Guion-Almeida in three Brazilian brothers. The new patient provides further evidence of the existence of this rare clinical entity.

Distribution and high frequency of novel alleles at NF1 polymorphic markers in the Italian population.

Segregation analysis of Neurofibromatosis type 1 (NF1) intragenic polymorphisms is a useful diagnostic tool for linkage analysis in familial cases and for the exclusion/detection of deletion in sporadic patients. We performed a segregation analysis of intragenic NF1 polymorphic markers in an Italian NF1 population consisting of 17 familial and 41 sporadic cases, for a total of 79 affected and 105 unaffected individuals. The haplotype in linkage with the mutation could be identified in all of the familial cases. Furthermore, an intragenic deletion was found in one sporadic case and confirmed by means of FISH using an NF1 IVS27 specific probe generated by a novel PCR procedure. In order to determine the allele frequencies at four NF1 polymorphisms in the Italian population, the unaffected family members and 25 unrelated Italian individuals were genotyped. Allele frequencies were found to be statistically different from those in the literature for markers IVS27AC28.4 and IVS38GT53.0. In addition four novel alleles were found in four unrelated subjects, and we observed a mutation during paternal gametogenesis in one case. These data suggest that NF1 polymorphic intragenic loci are unstable. It is unclear whether or not their marked instability may enhance the high mutation rate of the NF1 gene.

Molecular characterization of FRAXE-positive subjects with mental impairement in two unrelated Italian families.

The FRAXE fragile site, 600 Kb distal to the more common FRAXA, has been reported to be expressed in subjects with mild nonsyndromal mental retardation. Amplification of more than 200 GCC repeats associated with methylation of the adjacent CpG island at Xq28 is responsible for FRAXE fragility. We describe two unrelated, mentally retarded males identified during a screening for fragile X syndrome. Both index cases underwent FRAXE molecular analysis, following cytogenetic expression of the fra X site and negative FRAXA test. In family 1, we were able to investigate other 13 subjects over three generations, identifying two additional FRAXE-positive males, one with a fully mutated allele and one with a mosaic genotype. Detailed evaluation of physical traits and psychometric tests was performed on three retarded males from family 1 and the propositus from family 2. All of them were found to lack a definite phenotype, and showed different degrees of mental retardation. Slight mental retardation was evident in the mosaic male, suggesting that methylation might be an important determinant of mental impairment.