Ma Mencarelli

Novel FOXG1 mutations associated with the congenital variant of Rett syndrome

Background Rett syndrome is a severe neurodevelopmental disorder representing one of the most common genetic causes of mental retardation in girls. The classic form is caused by MECP2 mutations. In two patients affected by the congenital variant of Rett we have recently identified mutations in the FOXG1 gene encoding a brain specific transcriptional repressor, essential for early development of the telencephalon. Methods 60 MECP2/CDKL5 mutation negative European Rett patients (classic and variants), 43 patients with encephalopathy with early onset seizures, and four atypical Rett patients were analysed for mutations in FOXG1. Results and conclusions Mutations have been identified in four patients, independently classified as congenital Rett variants from France, Spain and Latvia. Clinical data have been compared with the two previously reported patients with mutations in FOXG1. In all cases hypotonia, irresponsiveness and irritability were present in the neonatal period. At birth, head circumference was normal while a deceleration of growth was recognised soon afterwards, leading to severe microcephaly. Motor development was severely impaired and voluntary hand use was absent. In contrast with classic Rett, patients showed poor eye contact. Typical stereotypic hand movements with hand washing and hand mouthing activities were present continuously. Some patients showed abnormal movements of the tongue and jerky movements of the limbs. Brain magnetic resonance imaging showed corpus callosum hypoplasia in most cases, while epilepsy was a variable sign. Scoliosis was present and severe in the older patients. Neurovegetative symptoms typical of Rett were frequently present.

Diagnostic criteria for the Zappella variant of Rett syndrome (the preserved speech variant)

The preserved speech variant is the milder form of Rett syndrome: affected girls show the same stages of this condition and by the second half of the first decade are making slow progress in manual and verbal abilities. They walk without help, and may be able to make simple drawings and write a few words. Most of them can speak in sentences. Autistic behavior can often be observed. We previously described several cases in the pre-molecular era and subsequently reported a survey of 12 cases with MECP2 mutations. Seventeen new patients with the preserved speech variant and a proven MECP2 mutation have been clinically evaluated. Additional clinical data of our previously described cases are reported. These 29 preserved speech variant cases were compared with 129 classic Rett patients using a clinical severity score system including 22 different signs. There was both statistical and clinical evidence of the existence of this variant. On the basis of their abilities these girls can be distinguished as low-, intermediate- and high-functioning. Girls of the last two groups show a greater homogeneity: they speak in sentences, use their hands more easily, have normal somatic features, mild neurovegetative abnormalities, with autistic behavior in 76%, epilepsy in 30%, while girls of the first group are closer to classic Rett syndrome. The majority of patients carries either missense mutations (especially the p.R133C change) or late truncating mutations in the MECP2 gene. These results confirm the existence of this variant of Rett syndrome (Zappella variant), a clear example of progress of manual and verbal abilities, and not of a preserved speech and suggest corresponding diagnostic criteria.

Early-onset seizure variant of Rett syndrome: Definition of the clinical diagnostic criteria

BACKGROUNDnRett syndrome is a severe neurodevelopmental disorder affecting almost exclusively females. Among Rett clinical variants, the early-onset seizure variant describes girls with early onset epilepsy and it is caused by mutations in CDKL5.nnnMETHODSnFour previously reported girls and five new cases with CDKL5 mutation, ranging from 14 months to 13 years, were evaluated by two clinical geneticists, classified using a severity score system based on the evaluation of 22 different clinical signs and compared with 128 classic Rett and 25 Zappella variant MECP2-mutated patients, evaluated by the same clinical geneticists. Clinical features were compared with previously described CDKL5 mutated patients. Both the statistical and the descriptive approach have been used to delineate clinical diagnostic criteria.nnnRESULTSnAll girls present epilepsy with onset varying from 10 days to 3 months. Patients may present different type of seizures both at onset and during the whole course of the disease; multiple seizure types may also occur in the same individual. After treatment with antiepileptic drugs patients may experience a short seizure-free period but epilepsy progressively relapses. Typical stereotypic hand movements severely affecting the ability to grasp are present. Psychomotor development is severely impaired. In the majority of cases head circumference is within the normal range both at birth and at the time of clinical examination.nnnCONCLUSIONnFor the practical clinical approach we propose to use six necessary and eight supportive diagnostic criteria. Epilepsy with onset between the first week and 5 months of life, hand stereotypies, as well as severe hypotonia, are included among the necessary criteria.

Xq28 duplications including MECP2 in five females: Expanding the phenotype to severe mental retardation

Duplications leading to functional disomy of chromosome Xq28, including MECP2 as the critical dosage-sensitive gene, are associated with a distinct clinical phenotype in males, characterized by severe mental retardation, infantile hypotonia, progressive neurologic impairment, recurrent infections, bladder dysfunction, and absent speech. Female patients with Xq duplications including MECP2 are rare. Only recently submicroscopic duplications of this region on Xq28 have been recognized in four females, and a triplication in a fifth, all in combination with random X-chromosome inactivation (XCI). Based on this small series, it was concluded that in females with MECP2 duplication and random XCI, the typical symptoms of affected boys are not present. We present clinical and molecular data on a series of five females with an Xq28 duplication including the MECP2 gene, both isolated and as the result of a translocation, and compare them with the previously reported cases of small duplications in females. The collected data indicate that the associated phenotype in females is distinct from males with similar duplications, but the clinical effects may be as severe as seen in males.

A 9.3 Mb microdeletion of 3q27.3q29 associated with psychomotor and growth delay, tricuspid valve dysplasia and bifid thumb

We describe a de novo 3q27.3q29 deletion in a 2.5-year-old female patient with developmental and growth delay, dysmorphic facial features, mild tricuspid valve dysplasia, bifid thumb, clinodactyly of the 2nd toe bilaterally and scoliosis. The deletion overlaps for about 1Mb with the 1.6Mb region commonly deleted in patients with 3q29 microdeletion syndrome. The phenotype of the two syndromes is not completely overlapping, though the most important clinical features, such as mental retardation and microcephaly, occur in both. This suggests that the deletion in our patient causes a distinct clinical phenotype, not described previously. In the deleted region there are 47 annotated genes. Among them, seven are of particular interest for correlation with clinical features of the patient. Two genes, OPA1 and CCDC50, responsible for autosomal dominant optic atrophy and deafness, respectively, may be important for the correct follow-up of the patient.

Expanding the phenotype associated with FOXG1 mutations and in vivo FoxG1 chromatin-binding dynamics.

Mutations in the Forkhead box G1 (FOXG1) gene, a brain specific transcriptional factor, are responsible for the congenital variant of Rett syndrome. Until now FOXG1 point mutations have been reported in 12 Rett patients. Recently seven additional patients have been reported with a quite homogeneous severe phenotype designated as the FOXG1 syndrome. Here we describe two unrelated patients with a de novo FOXG1 point mutation, p.Gln46X and p.Tyr400X, respectively, having a milder phenotype and sharing a distinctive facial appearance. Although FoxG1 action depends critically on its binding to chromatin, very little is known about the dynamics of this process. Using fluorescence recovery after photobleaching, we showed that most of the GFP‐FoxG1 fusion protein associates reversibly to chromatin whereas the remaining fraction is bound irreversibly. Furthermore, we showed that the two pathologic derivatives of FoxG1 described in this paper present a dramatic alteration in chromatin affinity and irreversibly bound fraction in comparison with Ser323fsX325 mutant (associated with a severe phenotype) and wild type Foxg1 protein. Our observations suggest that alterations in the kinetics of FoxG1 binding to chromatin might contribute to the pathological effects of FOXG1 mutations.

9q31.1q31.3 deletion in two patients with similar clinical features: A newly recognized microdeletion syndrome?

Interstitial deletions of the long arm of chromosome 9 are rare and most patients have been detected by conventional cytogenetic techniques. Disparities in size and localization are large and no consistent region of overlap has been delineated. We report two similar de novo deletions of 6.3u2009Mb involving the 9q31.1q31.3 region, identified in two monozygotic twins and one unrelated patient through array‐CGH analysis. By cloning the deletion breakpoints, we could show that these deletions are not mediated by segmental duplications. The patients displayed a distinct clinical phenotype characterized by mild intellectual disability, short stature with high body mass index, thick hair, arched eyebrows, flat profile with broad chin and mild prognathism, broad, and slightly overhanging tip of the nose, short neck with cervical gibbus. The twin patients developed a metabolic syndrome (type 2 diabetes, hypercholesterolemia, vascular hypertension) during the third decade of life. Although long‐term follow‐up and collection of additional patients will be needed to obtain a better definition of the phenotype, our findings characterize a previously undescribed syndromic disorder associated with haploinsufficiency of the chromosome 9q31.1q31.3 region.

P01.02: May the Silver‐Russell syndrome be suspected in utero by ultrasound?

Two placentas in singleton pregnancy with fused umbilical cord which has its own placental insertion site forming 3-vessel cord at fetal end is an extremely rare case. This present case describes two placentas with fused umbilical cord with an episode of vanishing twin syndrome and there seems to be a strong relationship between these two events. Therefore, as far as we know, this is the first case in the world which describes two placentas with fused umbilical cord related to vanishing twin syndrome. A 37-year-old woman, gravid 0, para 0, visited ER with an episode of vaginal bleeding without pelvic cramps at 8 weeks and 5 days of gestation and repeated ultrasonic exams revealed reabsorption of vanishing twin and two separate placentas on anterior and posterior body of uterus. At 40 weeks and 4 days, the patient delivered a viable female infant weighing 3900 g via Cesarean section and postpartum examination of the placentas and membranes confirmed two placentas with fused umbilical cord. Two placentas were almost equal in size and main placental disc cord had 2 arteries with one vein (3 vessel-cord) whereas side placental disc cord had one artery with one vein (2 vessel-cord). Several hypothesis including placenta abnormalities after IVF-ET procedure, succenturiate lobes and fetus-in-fetu were proposed.