Two novel pathogenic variants in MED13L: one familial and one isolated case.

BACKGROUND: Genetic variants involving the MED13L gene can lead to an autosomal dominant syndrome characterised by intellectual disability/developmental delay and facial dysmorphism. METHODS: We investigated two cases (one familial and one isolated) of intellectual disability with speech delay and dysmorphic facial features by whole-exome sequencing analyses. Further, we performed a literature review about clinical and molecular aspects of MED13L gene and syndrome. RESULTS: Two MED13L variants have been identified [MED13L(NM_015335.5):c.4417C>T and MED13L(NM_015335.5):c.2318delC] and were classified as pathogenic according to the ACMG (American College of Medical Genetics and Genomics) guidelines. One of the variants was present in sibs. CONCLUSIONS: The two pathogenic variants identified have not been previously reported. Importantly, this is the first report of a familial case of MED13L nonsense mutation. Although the parents of the affected children were no longer available for analysis, their apparently normal phenotypes were surmised from familial verbal descriptions corresponding to normal mental behaviour and phenotype. In this situation, the familial component of mutation transmission might be caused by gonadal mosaicism of a MED13L mutation in a gonad from either the father or the mother. The case reports and the literature review presented in this manuscript can be useful for genetic counselling.

The Y chromosome of the Atelidae family (Platyrrhini): study by chromosome microdissection.

In order to study the intergeneric variability of the Y chromosome, we describe the hybridization of the Y chromosome of Brachytelesarachnoides, obtained by microdissection, to metaphases of Atelesbelzebuthmarginatus, Lagothrixlagothricha, and Alouatta male specimens. Brachytelesarachnoides (Atelinae) has 62 chromosomes and a very small Y chromosome. Our results showed that the Brachytelesarachnoides Y chromosome probe hybridized to Lagothrixlagothricha metaphases yielding one hybridization signal on only the tiny Y chromosome, and when hybridized with Atelesbelzebuthmarginatus metaphases it yielded one hybridization signal on two thirds of the small acrocentric Y chromosome. However, no hybridization signal was observed in Alouatta metaphases (subfamily Alouattinae), a closely related genus in the Atelidae family. Furthermore, our data support a close phylogenetic relationship among Brachyteles, Ateles, and Lagothrix and their placement in the Atelinae subfamily, but exclude Alouatta from this group indicating its placement as basal to this group.

A 17q21.31 microdeletion encompassing the MAPT gene in a mentally impaired patient.

About 15% of patients with a clinical phenotype of Angelman syndrome (AS) have an unknown etiology. We report a patient with features reminiscent of AS, including a pattern of characteristic facial anomalies as well as speech impairment, developmental delay and frequent laughter. In addition, the patient had features not commonly associated with AS such as heart malformations and scoliosis. She was negative in SNURF-SNRPN exon 1 methylation studies and the G-banded karyotype was normal. Array-based comparative genomic hybridization disclosed a deletion of maximally 1 Mb at 17q21.31. The deleted region contains the MAPT gene, implicated in late onset neurodegenerative disorders, and the STH and NP_056258.1 genes. Another gene, such as CRHR1, might also be included based on maximum possible size of the deletion. We suggest that microdeletions within the 17q21.31 segment should be considered as a possible cause of phenotypes resembling AS, particularly when easily controlled seizures and/or cardiac abnormalities are also present.

Impact of molecular mechanisms, including deletion size, on Prader-Willi syndrome phenotype: study of 75 patients.

Prader-Willi syndrome (PWS) can result from a 15q11-q13 paternal deletion, maternal uniparental disomy (UPD), or imprinting mutations. We describe here the phenotypic variability detected in 51 patients with different types of deletions and 24 patients with UPD. Although no statistically significant differences could be demonstrated between the two main types of PWS deletion patients, it was observed that type I (BP1-BP3) patients acquired speech later than type II (BP2-BP3) patients. Comparing the clinical pictures of our patients with UPD with those with deletions, we found that UPD children presented with lower birth length and started walking earlier and deletion patients presented with a much higher incidence of seizures than UPD patients. In addition, the mean maternal age in the UPD group was higher than in the deletion group. No statistically significant differences could be demonstrated between the deletion and the UPD group with respect to any of the major features of PWS. In conclusion, our study did not detect significant phenotypic differences among type I and type II PWS deletion patients, but it did demonstrate that seizures were six times more common in patients with a deletion than in those with UPD.

Angelman syndrome associated with oculocutaneous albinism due to an intragenic deletion of the P gene.

Angelman syndrome (AS) is a neurodevelopmental disorder characterized by mental retardation, speech impairment, ataxia, and happy disposition with frequent smiling. AS results from the loss of expression of a maternal imprinted gene, UBE3A, mapped within 15q11-q13 region, due to different mechanisms: maternal deletion, paternal UPD, imprinting center mutation, and UBE3A mutation. Deletion AS patients may exhibit hypopigmentation of skin, eye, and hair correlating with deletion of P gene localized in the distal part of Prader-Willi (PWS)/AS region. Our patient presented developmental delay, severe mental retardation, absence of speech, outbursts of laughter, microcephaly, ataxia, hyperactivity, seizures, white skin, no retinal pigmentation, and gold yellow hair. His parents were of African ancestry. The SNURF-SNRPN methylation analysis confirmed AS diagnosis and microsatellite studies disclosed deletion with breakpoints in BP2 and BP3. All of the 25 exons and flanking introns of the P gene of the patient, his father, and mother were investigated. The patient is hemizygous for the deleted exon 7 of the P gene derived from his father who is a carrier of the deleted allele. Our patient manifests OCA2 associated with AS due to the loss of the maternal chromosome 15 with the normal P allele, and the paternal deletion in the P gene. As various degrees of hypopigmentation are associated with PWS and AS patients, the study of the P gene in a hemizygous state could contribute to the understanding of its effect on human pigmentation during development and to disclose the presence of modifier pigmentation gene(s) in the PWS/AS region.

Origin of uniparental disomy 15 in patients with Prader-Willi or Angelman syndrome.

Maternal uniparental disomy (UPD) accounts for approximately 25% of Prader-Willi patients (PWS) and paternal UPD for about 2-5% of Angelman syndrome (AS) patients. These findings and the parental origin of deletions are evidence of genomic imprinting in the cause of PWS and AS. The natural occurrence of UPD individuals allows the study of meiotic mechanisms resulting in chromosomal nondisjunction (ND). We selected patients with UPD15 from our sample of 30 PWS and 40 AS patients to study the origin of ND and the recombination along chromosome 15. These patients were analyzed with 10 microsatellites throughout the entire chromosome 15 (D15S541, D15S542, D15S11, D15S113, GABRB3, CYP19, D15S117, D15S131, D15S984, D15S115). The analysis disclosed seven heterodisomic PWS cases originating by meiosis I (MI) ND (four showed recombination and three no recombination), and one isodisomic PWS UPD15 originating by postzygotic duplication. Among the five paternal UPD15, we detected four isodisomies, three of which showed homozigosity for all markers, corresponding to a mitotic error, and one case originating from a paternal MII ND. Our results indicate that besides maternal MI and MII ND, paternal ND occurs when a PWS UPD15 patient originates from mitotic duplication of the maternal chromosome 15. ND events in AS are mainly due to mitotic errors, but paternal MII ND can occur and give origin to an AS UPD15 individual by two different mechanisms: rescue of a trisomic fetus or fertilization of a nullisomic egg with the disomic sperm, and in this case paternal and maternal ND are necessary.

Paternal UPD15: further genetic and clinical studies in four Angelman syndrome patients.

Among 25 patients diagnosed with Angelman syndrome, we detected 21 with deletion and 4 with paternal uniparental disomy (UPD), 2 isodisomies originating by postzygotic error, and 1 MII nondisjunction event. The diagnosis was obtained by molecular techniques, including methylation pattern analysis of exon 1 of SNRPN and microsatellite analysis of loci within and outside the 15q11-q13 region. Most manifestations present in deletion patients are those previously reported. Comparing the clinical data from our and published UPD patients with those with deletions we observed the following: the age of diagnosis is higher in UPD group (average 7 3/12 years), microcephaly is more frequent among deletion patients, UPD children start walking earlier (average age 2 9/12 years), whereas in deletion patients the average is 4 (1/2) years, epilepsy started later in UPD patients (average 5 10/12 years) than in deletion patients (average 1 11/12 years), weight above the 75th centile is reported mainly in UPD patients, complete absence of speech is more common in the deleted (88.9%) than in the UPD patients because half of the children are able to say few words. Thus, besides the abnormalities already described, the UPD patients have somewhat better verbal development, a weight above the 75th centile, and OFC in the upper normal range.

[Hypotonic infants and the Prader-Willi Syndrome] / Síndrome de Prader-Willi em lactentes hipotônicos.

OBJECTIVE: To describe 6 patients with less than 3 years of age that were diagnosed with Prader-Willi syndrome (PWS) due to hypotonia, poor sucking, slight facial anomalies and minor abnormalities of hands and feet. PWS is a neurobehavioural disorder characterized by two distinct phases; in the first, the neonate presents variable degree of hypotonia, feeding problems with none or poor sucking; hypogonadism, characteristic facial features with almond shaped eyes, narrow bifrontal diameter and down-turned corners of the mouth. Neuropsichymotor development is delayed. Hypotonia is non progressive and tends to improve between 8 and 11 months of age. The second phase then starts and is characterized by increasing hyperphagia and obesity, among other features. Unfortunately, most PWS patients are diagnosed only after obesity is installed. METHODS: Methylation, microsatellites analysis and karyotypic studies by traditional and in situ hybridization techniques were done. RESULTS: A deletion of chromosome segment 15q11q13 was disclosed in 4 and maternal disomy in two patients. CONCLUSION: The diagnosis of PWS is generally established after the onset of obesity. So, we suggest that the genetic analysis must be carried out in children with severe hypotonia of unknown cause, poor sucking and some facial features of PWS (small hands and feet, hypogonadism, hypopigmentation, almond eyes and narrow bifrontal diameter). This can allow the early diagnosis and avoid invasive exams necessary for neuromuscular disorder diagnosis like muscle biopsy and electroneuromiography, wich frequently are associated with inconclusives results.

Prader-Willi syndrome: genetic tests and clinical findings.

Here we describe the genetic studies performed in 53 patients with the suspected diagnosis of Prader-Willi syndrome (PWS). PWS is characterized by neonatal hypotonia, hypogonadism, delayed psychomotor development, hyperphagia, obesity, short stature, small hands and feet, learning disabilities, and obsessive-compulsive behavior. Through the methylation analysis of the SNRPN gene, microsatellite studies of loci mapped within and outside the PWS/AS region, and fluorescence in situ hybridization (FISH) study, we confirmed the diagnosis in 35 patients: 27 with a paternal deletion, and 8 with maternal uniparental disomy (UPD). The clinical comparisons between deleted and UPD patients indicated that there were no major phenotype differences, except for a lower birth length observed in the UPD children. Our sample was composed of more girls than boys; UPD patients were diagnosed earlier than the deleted cohort (2(10/12) s. 7(9/12) years); and, in the deleted group, the boys were diagnosed earlier than the girls (5(2/12) vs. 7(8/12) years, respectively).

Unusual clinical features in an Angelman syndrome patient with uniparental disomy due to a translocation 15q15q.

We had previously described a patient with an overgrowth syndrome and the chromosome constitution 45,XY,t(15q15q) (Wajntal et al., DNA Cell Biol 1993: 12: 227-231). Clinical reassessment and the use of molecular studies, including methylation analysis with an SNRPN probe, microsatellite analyses of D15S11, GABRB3 and D15S113 loci, and fluorescence in situ hybridization (FISH) using the SNRPN and GABRB3 probes, are consistent with a diagnosis of Angelman syndrome (AS) due to paternal isodisomy. This is the fourth report case of a translocation 15q15q with paternal uniparental disomy (UPD). Our findings suggest that some patients with clinical features of AS have hyperphagia and obesity with overgrowth, and that these features should not rule out a diagnosis of AS.

[Angelman syndrome: a frequently undiagnosed cause of mental retardation and epilepsy. Case report]. / Síndrome de Angelman. Causa frequentemente não reconhecida de deficiência mental e epilepsia. Relato de caso.

The authors describe the case of a typical Angelman syndrome patient. The proband presents developmental delay, mental retardation, macrostomia, wide-spaced teeth, seizures, absent speech, jerky gait, and paroxysms of laughter. The cytogenetic and molecular studies showed a maternal deletion of 15q11q13. These results are in agreement with the clinical diagnosis of Angelman syndrome.

Neuroblastoma in a boy with MCA/MR syndrome, deletion 11q, and duplication 12q.

Deletion 11q23-->qter and duplication 12q23-->qter are described in a boy with neuroblastoma, multiple congenital anomalies, and mental retardation. The patient has clinical manifestations of 11q deletion and 12q duplication syndromes. The possible involvement of the segment 11q23-->24 in the cause of the neuroblastoma is discussed.

Incontinentia pigmenti achromians (hypomelanosis of ITO, MIM 146150): further evidence of localization at Xp11.

We report on a girl with apparent hypomelanosis of Ito (ITO); cytogenetic studies disclosed the karyotype 46,X,t(X;10)(p11;q11)mat. We present further evidence that at least one of the genetic forms of ITO is located at Xp11; reviewing the clinical characteristics of patients with incontinentia pigmenti type 1 (IP1) and ITO with X-autosome translocations, we suggest that IP1 and ITO represent allelic forms or a contiguous gene syndrome. Thus, different genetic alterations in this region (Xp11) give rise to ITO or IP1 or borderline phenotypes. We also suggest that all patients with ITO, due to Xp11 mutation, have functional or genetic mosaicisms.

Macrosomia, obesity, macrocephaly and ocular abnormalities (MOMO syndrome) in two unrelated patients: delineation of a newly recognized overgrowth syndrome.

We describe 2 unrelated patients, a boy and a girl, with an overgrowth syndrome and the following common characteristics: macrocrania, obesity, ocular abnormalities (retinal coloboma and nystagmus), downward slant of palpebral fissures, mental retardation, and delayed bone maturation. Both cases are of sporadic occurrence with no consanguinity between the parents. We suggest that this syndrome is due to a new autosomal dominant mutation and propose to designate it with the acronym of "MOMO syndrome" (Macrosomia, Obesity, Macrocrania, Ocular anomalities.

Cytogenetic evidence of involvement of chromosome regions 15q12 and 12q15 in conditions with associated overgrowth.

Syndromes with associated overgrowth are poorly understood. Besides their mode of inheritance, nothing is known regarding the basic genetic alterations that lead to their abnormal phenotypic manifestations. The chromosome localization of the genes involved remains unknown for this group of syndromes, with the only exception being the Wiedemann-Beckwith syndrome.

[Macrosomia, macrocrania and motor disorders in childhood, Sotos syndrome (McKusick 11755): report of 7 cases and review of clinical aspects of 198 reported cases]. / Macrossomia, macrocrania e incoordenação motora da infância: síndrome de Sotos (McKusick 11755): estudo de 7 casos e revisão de aspectos clínicos de 198 casos publicados.

Children with Sotos syndrome have growth acceleration, macrocephaly, acromegaloid features and delay in neuropsychomotor development during infancy. Syndrome delineation and differential diagnosis are based on evaluation of phenotypic characteristics and evolutive history of the patients. Seven patients with this syndrome are reported, and the relative occurrence of the phenotypic characteristics present in 198 reported cases are reviewed. Motor difficulties present in those patients during early infancy are responsible for the poor performance on IQ tests. Oriented stimulation should be encouraged in order to help the affected children to overcome their initial difficulties and to achieve normal scholarity and life performance.