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.

A Multicentric Brazilian Investigative Study of Copy Number Variations in Patients with Congenital Anomalies and Intellectual Disability

Genomic imbalances are the most common cause of congenital anomalies (CA) and intellectual disability (ID). The aims of this study were to identify copy number variations (CNVs) in 416 patients with CA and ID from 5 different genetics centers within 4 different states by using the Multiplex Ligation-dependent Probe Amplification (MLPA) technique and to apply the chromosomal microarray (CMA) methodology in selected cases. The samples were analyzed by MLPA kits P064, P036, P070 and P250. Positive results were found in 97/416 (23.3%) patients. CMA was applied in 14 selected cases. In 6/14 (42.85%) patients, CMA detected other copy number variations not detected by the MLPA studies. Although CMA is indispensable for genotype refinement, the technique is still unfeasible in some countries as a routine analysis due to economic and technical limitations. In these cases, clinical evaluation followed by karyotyping and MLPA analysis is a helpful and affordable solution for diagnostic purposes.

Richieri-Costa-Pereira syndrome: Expanding its phenotypic and genotypic spectrum

Richieri-Costa-Pereira syndrome is a rare autosomal recessive acrofacial dysostosis that has been mainly described in Brazilian individuals. The cardinal features include Robin sequence, cleft mandible, laryngeal anomalies and limb defects. A biallelic expansion of a complex repeated motif in the 5' untranslated region of EIF4A3 has been shown to cause this syndrome, commonly with 15 or 16 repeats. The only patient with mild clinical findings harbored a 14-repeat expansion in 1 allele and a point mutation in the other allele. This proband is described here in more details, as well as is his affected sister, and 5 new individuals with Richieri-Costa-Pereira syndrome, including a patient from England, of African ancestry. This study has expanded the phenotype in this syndrome by the observation of microcephaly, better characterization of skeletal abnormalities, less severe phenotype with only mild facial dysmorphisms and limb anomalies, as well as the absence of cleft mandible, which is a hallmark of the syndrome. Although the most frequent mutation in this study was the recurrent 16-repeat expansion in EIF4A3, there was an overrepresentation of the 14-repeat expansion, with mild phenotypic expression, thus suggesting that the number of these motifs could play a role in phenotypic delineation.

Short Communication Impact of early enzyme-replacement therapy for mucopolysaccharidosis VI: results of a long-term follow-up of Brazilian siblings

Mucopolysaccharidosis type VI (MPS VI) is an autosomal recessive multisystem lysosomal storage disorder, which is characterized by the deficiency of the enzyme arylsulfatase B encoded by the ARSB gene. Treatment of this disease with enzyme-replacement therapy (ERT) improves the clinical status of and generates hope for MPS VI patients. However, only few reports on patients with MPS VI treated before 5 years of age have been published. Thus, the objective of this study was to compare the clinical parameters of two sisters affected by MPS VI who started ERT at different ages (9 years and 1 year 5 months, respectively) and to determine the most relevant clinical impacts of early treatment after 85 months of evaluation. The treatment was well tolerated by both siblings. ERT in the younger sibling resulted in increased growth, an improved 6-minute walk test, less coarse face, slower progression of cardiac valve disease, and the absence of compressive myelopathy compared to that in her older sister. On the other hand, the older sibling had typical MPS VI phenotypic features before the commencement of ERT. Corneal clouding, clawed hands, and progressive skeletal changes were observed in both siblings despite the treatment. Both siblings displayed reduced frequencies of upper respiratory infections and apnea indices. This study emphasizes that early diagnosis and treatment of MPS VI are critical for a better disease outcome and to enhance the quality of life for these patients.

Case report. Johanson-Blizzard syndrome: a report of gender-discordant twins with a novel UBR1 mutation

Johanson-Blizzard syndrome (JBS) is a rare autosomal recessive disorder resulting from loss-of-function mutations in the UBR1 gene. JBS can be easily recognized by its unique clinical presentation (including exocrine pancreatic insufficiency, hypoplasia/aplasia of the alae nasi, congenital scalp defects, sensorineural hearing loss, growth retardation, psychomotor retardation, and anal and genitourinary anomalies). The objective of this study is to report on the first familial case of gender-discordant twins presenting JBS and a novel mutation in the UBR1 gene. We also review literature describing molecularly confirmed cases of JBS. The female twin developed refractory severe diarrhea after the second month of life and died at the age of 3 months. The male twin also developed diarrhea and failure to thrive after the 3 month of life but improved when nutrition support and pancreatic enzyme replacement was started, and he has survived into adolescence. Both patients presented typical clinical features of JBS. A homozygous nonsense mutation (c.3682C>T; p.Q1228X) in UBR1 was confirmed. Severe presentation of JBS usually involves deleterious (nonsense, frameshift, or splice-site) mutations in the UBR1 gene that are thought to completely abolish the expression of a functional protein product, as in this familial case; however, milder presentation of JBS has occasionally been observed with missense mutations in at least 1 of the 2 copies of UBR1, in which there may be residual activity of the product of this gene. Early diagnosis and adequate treatment are crucial for a favorable outcome.

Report of a Large Brazilian Family With a Very Attenuated Form of Hunter Syndrome (MPS II)

Hunter syndrome, or Mucopolysaccharidosis type II (MPS II), is a rare X-linked recessive disorder caused by a deficiency of the lysosomal enzyme iduronate-2-sulfatase (IDS). The phenotypic spectrum varies from severe to attenuated clinical forms. We report a large Brazilian family with 16 affected individuals exhibiting a very attenuated form of MPS II. Fourteen female carriers were also identified. Twelve affected male patients, whose ages ranged from 1 to 35 years, were examined. Molecular analysis showed a novel missense mutation (p.A77D) in the IDS gene, confirming the diagnosis. Nine of the family members presented some degree of heart damage, though only the proband became symptomatic and required heart transplantation. One 19-year-old adult and 1-year-old twin boys each had a normal echocardiogram. Short stature was found in two adults while macrocephaly was found in one; the remaining adults had anthropometric measures within normal range. All affected adults had normal cognitive development and were able to perform normal daily activities, except one who had mild learning disability. Two patients died due to natural causes beyond 70 years of age. The female carriers did not present any signs of disease. In this large family with a mild form of MPS II and variable degree of clinical manifestations, it is noteworthy that several affected individuals have remained asymptomatic even at advanced age and even without enzyme replacement therapy.

An Illustrative Case of Neurofibromatosis Type 1 and NF1 Microdeletion

We report on a patient with NF1 microdeletion and clinical manifestations that fulfill the diagnostic criteria for neurofibromatosis type 1 but also presenting features reminiscent of Proteus syndrome.

High frequency of submicroscopic chromosomal imbalances in patients with syndromic craniosynostosis detected by a combined approach of microsatellite segregation analysis, multiplex ligation-dependent probe amplification and array-based comparative genome hybridisation

We present the first comprehensive study, to our knowledge, on genomic chromosomal analysis in syndromic craniosynostosis. In total, 45 patients with craniosynostotic disorders were screened with a variety of methods including conventional karyotype, microsatellite segregation analysis, subtelomeric multiplex ligation-dependent probe amplification) and whole-genome array-based comparative genome hybridisation. Causative abnormalities were present in 42.2% (19/45) of the samples, and 27.8% (10/36) of the patients with normal conventional karyotype carried submicroscopic imbalances. Our results include a wide variety of imbalances and point to novel chromosomal regions associated with craniosynostosis. The high incidence of pure duplications or trisomies suggests that these are important mechanisms in craniosynostosis, particularly in cases involving the metopic suture.

Whole-genome array-CGH screening in undiagnosed syndromic patients: old syndromes revisited and new alterations

We report array-CGH screening of 95 syndromic patients with normal G-banded karyotypes and at least one of the following features: mental retardation, heart defects, deafness, obesity, craniofacial dysmorphisms or urogenital tract malformations. Chromosome imbalances not previously detected in normal controls were found in 30 patients (31%) and at least 16 of them (17%) seem to be causally related to the abnormal phenotypes. Eight of the causative imbalances had not been described previously and pointed to new chromosome regions and candidate genes for specific phenotypes, including a connective tissue disease locus on 2p16.3, another for obesity on 7q22.1-->q22.3, and a candidate gene for the 3q29 deletion syndrome manifestations. The other causative alterations had already been associated with well-defined phenotypes including Sotos syndrome, and the 1p36 and 22q11.21 microdeletion syndromes. However, the clinical features of these latter patients were either not typical or specific enough to allow diagnosis before detection of chromosome imbalances. For instance, three patients with overlapping deletions in 22q11.21 were ascertained through entirely different clinical features, i.e., heart defect, utero-vaginal aplasia, and mental retardation associated with psychotic disease. Our results demonstrate that ascertainment through whole-genome screening of syndromic patients by array-CGH leads not only to the description of new syndromes, but also to the recognition of a broader spectrum of features for already described syndromes. Furthermore, on the technical side, we have significantly reduced the amount of reagents used and costs involved in the array-CGH protocol, without evident reduction in efficiency, bringing the method more within reach of centers with limited budgets.

CHILD syndrome caused by a deletion of exons 6-8 of the NSDHL gene

The X-linked dominant CHILD syndrome (congenital hemidysplasia with ichthyosiform nevus and limb defects) is a rare developmental defect characterized by a strictly lateralized inflammatory nevus. In the majority of cases, the right side of the body is affected. Ipsilateral hypoplastic lesions may involve the brain, skeletal structures, lungs, heart or kidneys. We describe a case of CHILD syndrome involving the left side of the body. Absence of metacarpal, metatarsal and phalangeal bones of the left hand and foot resulted in oligodactyly, with only 3 fingers and 1 toe. An ipsilateral inflammatory epidermal nevus with hyperkeratosis, parakeratosis, acanthosis and perivascular lymphohistiocytic infiltrate was strictly confined to the left half of the patient's body. The phenotype was shown to be associated with a deletion of exons 6-8 of the X-linked NSDHL gene, confirming that CHILD syndrome is due to loss of function of an enzyme involved in cholesterol biosynthesis.

Are Noonan syndrome and Noonan-like/multiple giant cell lesion syndrome distinct entities?

We report on a family with typical clinical findings of Noonan syndrome associated with giant cell lesions in maxilla and mandible. We discuss the obvious clinical overlap between Noonan syndrome and Noonan-like/multiple giant cell lesion syndrome, and we give further clinical and molecular support that these two entities could be allelic conditions.

Cardiac findings in 31 patients with Noonan's syndrome

OBJECTIVE

To evaluate cardiac findings in 31 Noonan syndrome patients.

METHODS

Thirty-one (18 males and 13 females)patients from 26 families affected with Noonan's syndrome were evaluated from the cardiac point of view with electrocardiography and Doppler echocardiography.

RESULTS

Twenty patients had some type of cardiac abnormality. The most frequent was pulmonary valve stenosis followed by hypertrophic myocardiopathy, commonly associated with valve defects. Upper deviation of the QRS axis was observed in 80% of these patients.

CONCLUSION

In view of the high frequency and diversity of cardiac abnormalities present in Noonan syndrome, cardiac evaluation with electrocardiography and echocardiography should be performed in all patients diagnostically suspected of having this disease.

Clinical and laboratorial study of 19 cases of mucopolysaccharidoses

The mucopolysaccharidoses (MPS) are a heterogeneous group of inborn errors of lysosomal glycosaminoglycan (GAG) metabolism. The importance of this group of disorders among the inborn errors of metabolism led us to report 19 cases.

METHOD

We performed clinical, radiological, and biochemical evaluations of the suspected patients, which allowed us to establish a definite diagnosis in 19 cases.

RESULTS

Not all patients showed increased GAG levels in urine; enzyme assays should be performed in all cases with strong clinical suspicion. The diagnosis was made on average at the age of 48 months, and the 19 MPS cases, after a full clinical, radiological, and biochemical study, were classified as follows: Hurler - MPS I (1 case); Hunter - MPS II (2 cases); Sanfilippo - MPS III (2 cases); Morquio - MPS IV (4 cases); Maroteaux-Lamy - MPS VI (9 cases); and Sly - MPS VII (1 case).

DISCUSSION

The high relative frequency of Maroteaux-Lamy disease contrasts with most reports in the literature and could express a population variability.

AEC syndrome and CHAND syndrome: further evidence of clinical overlapping in the ectodermal dysplasias

Among the ectodermal dysplasias, there are several examples of overlapping phenotypes in disorders that are considered distinct. We report a 5-year-old boy born to nonconsanguineous parents and presenting with ectodermal dysplasia, ankyloblepharon filiforme adnatum, and bilateral choanal atresia consistent with the diagnosis of AEC syndrome. We compare the findings in our patient with the previous reported cases and discuss the overlapping phenotype of this disorder with CHAND syndrome.

Noonan syndrome: a clinical and genetic study of 31 patients

Noonan syndrome is a multiple congenital anomaly syndrome, inherited in an autosomal dominant pattern. We studied 31 patients (18 males and 13 females) affected by this disorder regarding their clinical and genetic characteristics. The most frequent clinical findings were short stature (71%); craniofacial dysmorphisms, especially hypertelorism, ptosis, downslanting of the palpebral fissures; short or webbed neck (87%); cardiac anomalies (65%), and fetal pads in fingers and toes (70%). After studying the probands' first-degree relatives, we made the diagnosis of Noonan syndrome in more than one family member in three families. Therefore, the majority of our cases were sporadic.

Acro-oto-ocular syndrome: further evidence for a new autosomal recessive disorder

We report on a patient born to consanguineous parents and presenting with pseudopapilledema, mixed hearing loss, and minor facial and limb anomalies. To our knowledge, there is just one similar description of this syndrome in three members of a Brazilian kindred whose parents were also consanguineous, suggesting autosomal recessive inheritance. We compare the findings of our patient with these previous reported cases and discuss the differential diagnoses of this new syndrome, which we suggest be named the acro-oto-ocular syndrome.