Secondary hemophagocytic lymphohystiocytosis in a Rubinstein Taybi syndrome patient.

Rubinstein-Taybi syndrome (RSTS) is an autosomal dominant disorder, caused by variants in CREBBP or EP300. Affected individuals present with distinctive craniofacial features, broad thumbs and/or halluces, intellectual disability and immunodeficiency. Here we report on one RSTS patient who experienced hemophagocytic lymphohystiocytosis (HLH) and disseminated herpes virus 1 ( HSV-1) disease. The clinical picture of RSTS is expanding to include autoinflammatory, autoimmune, and infectious complications. Prompt treatment of HLH and disseminated HSV-1 can lower the mortality rate of these life-threatening conditions.

Genetics of Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome.

Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, also referred to as Müllerian agenesis, is the second most common cause of primary amenorrhea. It is characterized by congenital absence of the uterus, cervix, and the upper part of the vagina in otherwise phenotypically normal 46,XX females. MRKH syndrome has an incidence of about 1 in 4,500-5,000 newborn females and it is generally divided into two subtypes: MRKH type 1, in which only the upper vagina, cervix and the uterus are affected, and MRKH type 2, which is associated with additional malformations generally affecting the renal and skeletal systems, and also includes MURCS (MÜllerian Renal Cervical Somite) characterized by cervico-thoracic defects. MRKH syndrome is mainly sporadic; however, familial cases have been described indicating that, at least in a subset of patients, MRKH may be an inherited disorder. The syndrome appears to demonstrate an autosomal dominant inheritance pattern, with incomplete penetrance and variable expressivity. The etiology of MRKH syndrome is still largely unknown, probably because of its intrinsic heterogeneity. Several candidate causative genes have been investigated, but to date only WNT4 has been associated with MRKH with hyperandrogenism. This review summarizes and discusses the clinical features and details progress to date in understanding the genetics of MRKH syndrome.

Expanding the clinical spectrum of the 'HDAC8-phenotype' - implications for molecular diagnostics, counseling and risk prediction.

Cornelia de Lange syndrome (CdLS) is a clinically heterogeneous disorder characterized by typical facial dysmorphism, cognitive impairment and multiple congenital anomalies. Approximately 75% of patients carry a variant in one of the five cohesin-related genes NIPBL, SMC1A, SMC3, RAD21 and HDAC8. Herein we report on the clinical and molecular characterization of 11 patients carrying 10 distinct variants in HDAC8. Given the high number of variants identified so far, we advise sequencing of HDAC8 as an indispensable part of the routine molecular diagnostic for patients with CdLS or CdLS-overlapping features. The phenotype of our patients is very broad, whereas males tend to be more severely affected than females, who instead often present with less canonical CdLS features. The extensive clinical variability observed in the heterozygous females might be at least partially associated with a completely skewed X-inactivation, observed in seven out of eight female patients. Our cohort also includes two affected siblings whose unaffected mother was found to be mosaic for the causative mutation inherited to both affected children. This further supports the urgent need for an integration of highly sensitive sequencing technology to allow an appropriate molecular diagnostic, genetic counseling and risk prediction.

Recognition of the Cornelia de Lange syndrome phenotype with facial dysmorphology novel analysis.

Facial analysis systems are becoming available to healthcare providers to aid in the recognition of dysmorphic phenotypes associated with a multitude of genetic syndromes. These technologies automatically detect facial points and extract various measurements from images to recognize dysmorphic features and evaluate similarities to known facial patterns (gestalts). To evaluate such systems' usefulness for supporting the clinical practice of healthcare professionals, the recognition accuracy of the Cornelia de Lange syndrome (CdLS) phenotype was examined with FDNA's automated facial dysmorphology novel analysis (FDNA) technology. In the first experiment, 2D facial images of CdLS patients with either an NIPBL or SMC1A gene mutation as well as non-CdLS patients which were assessed by dysmorphologists in a previous study were evaluated by the FDNA technology; the average detection rate of experts was 77% while the system's detection rate was 87%. In the second study, when a new set of NIPBL, SMC1A and non-CdLS patient photos was evaluated, the detection rate increased to 94%. The results from both studies indicated that the system's detection rate was comparable to that of dysmorphology experts. Therefore, utilizing such technologies may be a useful tool in a clinical setting.

Broadening of cohesinopathies: exome sequencing identifies mutations in ANKRD11 in two patients with Cornelia de Lange-overlapping phenotype.

Cornelia de Lange syndrome (CdLS) and KBG syndrome are two distinct developmental pathologies sharing common features such as intellectual disability, psychomotor delay, and some craniofacial and limb abnormalities. Mutations in one of the five genes NIPBL, SMC1A, SMC3, HDAC8 or RAD21, were identified in at least 70% of the patients with CdLS. Consequently, additional causative genes, either unknown or responsible of partially merging entities, possibly account for the remaining 30% of the patients. In contrast, KBG has only been associated with mutations in ANKRD11. By exome sequencing we could identify heterozygous loss-of-function mutations in ANKRD11 in two patients with the clinical diagnosis of CdLS. Both patients show features reminiscent of CdLS such as characteristic facies as well as a small head circumference which is not described for KBG syndrome. Patient A, who carries the mutation in a mosaic state, is a 4-year-old girl with features reminiscent of CdLS. Patient B, a 15-year-old boy, shows a complex phenotype which resembled CdLS during infancy, but has developed to a more KBG overlapping phenotype during childhood. These findings point out the importance of screening ANKRD11 in young CdLS patients who were found to be negative for mutations in the five known CdLS genes.

Insights into genotype-phenotype correlations from CREBBP point mutation screening in a cohort of 46 Rubinstein-Taybi syndrome patients.

The genetic basis of Rubinstein-Taybi syndrome (RSTS), a rare, sporadic, clinically heterogeneous disorder characterized by cognitive impairment and a wide spectrum of multiple congenital anomalies, is primarily due to private mutations in CREBBP (approximately 55% of cases) or EP300 (approximately 8% of cases). Herein, we report the clinical and the genetic data taken from a cohort of 46 RSTS patients, all carriers of CREBBP point mutations. Molecular analysis revealed 45 different gene alterations including 31 inactivating (21 frameshift and 10 nonsense), 10 missense and 4 splicing mutations. Bioinformatic tools and transcript analyses were used to predict the functional effects of missense and splicing alterations. Of the 45 mutations, 42 are unreported and 3 were described previously. Recurrent mutations maybe a key tool in addressing genotype-phenotype correlations in patients sharing the same defects (at the genomic or transcript level) and specific clinical signs, demonstrated here in two cases. The clinical data of our cohort evidenced frequent signs such as arched eyebrows, epicanthus, synophrys and/or frontal hypertrichosis and broad phalanges that, previously overlooked in RSTS diagnosis, now could be considered. Some suggested correlations between organ-specific anomalies and affected CREB-binding protein domains broaden the RSTS clinical spectrum and perhaps will enhance patient follow-up and clinical care.

Clinical and molecular characterization of Rubinstein-Taybi syndrome patients carrying distinct novel mutations of the EP300 gene.

Rubinstein-Taybi syndrome (RSTS) is a rare congenital neurodevelopmental disorder characterized by postnatal growth deficiency, skeletal abnormalities, dysmorphic features and cognitive deficit. Mutations in two genes, CREBBP and EP300, encoding two homologous transcriptional co-activators, have been identified in ˜55% and ˜3-5% of affected individuals, respectively. To date, only eight EP300-mutated RSTS patients have been described and 12 additional mutations are reported in the database LOVD. In this study, EP300 analysis was performed on 33 CREBBP-negative RSTS patients leading to the identification of six unreported germline EP300 alterations comprising one deletion and five point mutations. All six patients showed a convincing, albeit mild, RSTS phenotype with minor skeletal anomalies, slight cognitive impairment and few major malformations. Beyond the expansion of the RSTS-EP300-mutated cohort, this study indicates that EP300-related RSTS cases occur more frequently than previously thought (˜8% vs 3-5%); furthermore, the characterization of novel EP300 mutations in RSTS patients will enhance the clinical practice and genotype-phenotype correlations.

Histone acetylation deficits in lymphoblastoid cell lines from patients with Rubinstein-Taybi syndrome.

BACKGROUND: Rubinstein-Taybi syndrome (RSTS) is a congenital neurodevelopmental disorder defined by postnatal growth deficiency, characteristic skeletal abnormalities and mental retardation and caused by mutations in the genes encoding for the transcriptional co-activators with intrinsic lysine acetyltransferase (KAT) activity CBP and p300. Previous studies have shown that neuronal histone acetylation is reduced in mouse models of RSTS. METHODS: The authors identified different mutations at the CREBBP locus and generated lymphoblastoid cell lines derived from nine patients with RSTS carrying distinct CREBBP mutations that illustrate different grades of the clinical severity in the spectrum of the syndrome. They next assessed whether histone acetylation levels were altered in these cell lines. RESULTS: The comparison of CREBBP-mutated RSTS cell lines with cell lines derived from patients with an unrelated mental retardation syndrome or healthy controls revealed significant deficits in histone acetylation, affecting primarily histone H2B and histone H2A. The most severe defects were observed in the lines carrying the whole deletion of the CREBBP gene and the truncating mutation, both leading to a haploinsufficiency state. Interestingly, this deficit was rescued by treatment with an inhibitor of histone deacetylases (HDACi). CONCLUSIONS: The authors' results extend to humans the seminal observations in RSTS mouse models and point to histone acetylation defects, mainly involving H2B and H2A, as relevant molecular markers of the disease.

Somatic mosaicism in Cornelia de Lange syndrome: a further contributor to the wide clinical expressivity?

Cornelia de Lange syndrome (CdLS) is a rare, congenital syndrome characterized by growth retardation, dysmorphic face, mental retardation and limb reduction defects. Clinical manifestations of CdLS can be extremely variable. Mutations in NIPBL, SMC1A and SMC3 genes, encoding for a regulator and two subunits of the cohesin complex, respectively, are found in 60-65% of CdLS patients. We report on a male with CdLS who is mosaic for the c.2827delA mutation in the NIPBL gene. Allele quantitation by pyrosequencing showed the presence of the mutation in about 10% and 33% of DNA samples from peripheral blood and buccal smears, respectively. The patient shows a complex phenotype: growth and psychomotor retardation are characteristic of the severe forms of CdLS, while the absence of severe limb reduction defects and major malformations are typical of the mild phenotype. He also has depigmentation areas following Blashko lines, an unusual finding in CdLS, which has been associated with mosaicism in other genetic conditions. This case represents the first evidence of somatic mosaicism in CdLS and explains the mild phenotype in the patient as compared to that predicted by a truncating mutation. Besides confirming the clinical and genetic heterogeneity of CdLS, this case also raises the likely underestimated mutation rate of known genes and points to the complexity of addressing genotype-phenotype correlations.

Search for genomic imbalances in a cohort of 24 Cornelia de Lange patients negative for mutations in the NIPBL and SMC1L1 genes.

Cornelia de Lange syndrome (CdLS) is a rare, multiple congenital anomaly/mental retardation syndrome characterized by varied clinical signs including facial dysmorphism, pre- and post-natal growth defects, small hands and malformations of the upper limbs. Established genetic causes include mutations in the NIPBL (50-60%), SMC1L1 and SMC3 (5%) genes. To detect chromosomal rearrangements pointing to novel positional candidate CdLS genes, we used array-CGH to analyze a subgroup of 24 CdLS patients negative for mutations in the NIPBL and SMC1L1 genes. We identified three carriers of DNA copy number alterations, including a de novo 15q26.2-qter 8-Mb deletion, and two inherited 13q14.2-q14.3 1-Mb deletion and 13q21.32-q21.33 1.5-Mb duplication, not reported among copy number variants. The clinical presentation of all three patients matched the diagnostic criteria for CdLS, and the phenotype of the patient with the 15qter deletion is compared to that of both CdLS and 15qter microdeletion patients.

Clinical score of 62 Italian patients with Cornelia de Lange syndrome and correlations with the presence and type of NIPBL mutation.

Cornelia de Lange syndrome (CdLS) is a rare multisystem disorder characterized by facial dysmorphisms, upper limb abnormalities, growth and cognitive retardation. About half of all patients with CdLS carry mutations in the NIPBL gene. The first Italian CdLS cohort involving 62 patients (including 4 related members) was screened for NIPBL mutations after a clinical evaluation using a quantitative score that integrates auxological, malformation and neurodevelopmental parameters. The patients were classified as having an overall 'severe', 'moderate' or 'mild' phenotype. NIPBL screening showed 26 mutations so classified: truncating (13), splice-site (8), missense (3), in-frame deletion (1) and regulatory (1). The truncating mutations were most frequently found in the patients with a high clinical score, whereas most of the splice-site and all missense mutations clustered in the low-medium score groups. The NIPBL-negative group included patients covering the entire clinical spectrum. The prevalence of a severe phenotype in the mutated group and a mild phenotype in the non-mutated group was statistically significant. In terms of the isolated clinical signs, the statistically significant differences between the mutation-positive and mutation-negative individuals were pre- and post-natal growth deficits, limb reduction, and delayed speech development. The proposed score seems to be a valuable means of prioritizing the patients with CdLS to undergo an NIPBL mutation test.

Identification of duplicated genes in 17q11.2 using FISH on stretched chromosomes and DNA fibers.

Recent evidence has been provided that links duplicons (REP-P and REP-M) in 17q11.2 flanking the neurofibromatosis type 1 (NF1) gene to the breakpoints of the NF1 microdeletion syndrome. The physical mapping and structural definition of duplicated regions is often impossible by conventional approaches, and so we have used high resolution fluorescence in situ hybridization (FISH) with locus-specific probes of limited size on chromosomes stretched to different degrees to identify novel duplicated genes and expressed sequence tags (ESTs) mapping to 17q11.2. This approach has allowed us to detect and map duplications of the BLMH and GOS28 genes, with one copy lying centromeric and one telomeric to the NF1 gene, and an SHGC30113 transcript with one copy being adjacent and the other distal to the NF1 3' untranslated region. Double-color FISH with a BLMH-specific probe on stretched chromosomes showed that the telomeric BLMH repeat lacked the 5' end of the gene and was 0.8 Mb from its centromeric copy. The distance between the SHGC30113 repeats was estimated as being 500 kb by double-color FISH on highly stretched chromosomes and DNA fibers. The latter approach revealed adjacent SHGC30113-BLMH-specific signals relating to the incomplete BLMH copy. The use of FISH on stretched chromosomes and, where applicable DNA fibers, is a powerful tool for identifying and finely characterizing duplicated regions whose mapping by the classical physical mapping approach is often precluded.