The first Brazilian clinical report of Kleefstra syndrome, including semicircular canals agenesis as a possible phenotype expansion

OBJECTIVE

to report the first case series of Brazilian children diagnosed with Kleefstra syndrome, present a possible phenotype expansion to the syndrome and to raise physicians' awareness for this rare disease.

RESULTS

seven patients with confirmed KS were evaluated, including 5 males and 2 females. Abnormal prenatal findings were observed in 4 patients. Most patients were born at term, with normal birth measurements. All patients had neurodevelopmental delay and 6 evolved with intellectual disability. Hearing loss was present in 57.1% of patients and 28.7% had congenital heart disease. In males, cryptorchidism was present in 75%. Despite the facial dysmorphisms, only 2 out of 7 patients had a pre-test clinical suspicion of KS. One specific patient presented bilateral agenesis of the semicircular canals, a very rare ear manifestation in Kleefstra syndrome, representing a possible phenotype expansion of the syndrome.

CONCLUSION

this report aims to promote awareness among physicians evaluating patients in a context of neurodevelopmental delay or congenital malformations, especially congenital heart defects. We also highlight a possible phenotype expansion of the syndrome, with a case of semicircular anomaly, not reported in this syndrome so far.

Arrhythmias including atrial fibrillation and congenital heart disease in Kleefstra syndrome: a possible epigenetic link

AIMS

Kleefstra syndrome (KS), often diagnosed in early childhood, is a rare genetic disorder due to haploinsufficiency of EHMT1 and is characterized by neuromuscular and intellectual developmental abnormalities. Although congenital heart disease (CHD) is common, the prevalence of arrhythmias and CHD subtypes in KS is unknown.

METHODS AND RESULTS

Inspired by a novel case series of KS patients with atrial tachyarrhythmias in the USA, we evaluate the two largest known KS registries for arrhythmias and CHD: Radboudumc (50 patients) based on health record review at Radboud University Medical Center in the Netherlands and GenIDA (163 patients) based on worldwide surveys of patient families. Three KS patients (aged 17-25 years) presented with atrial tachyarrhythmias without manifest CHD. In the international KS registries, the median [interquartile range (IQR)] age was considerably younger: GenIDA/Radboudumc at 10/13.5 (12/13) years, respectively. Both registries had a 40% prevalence of cardiovascular abnormalities, the majority being CHD, including septal defects, vascular malformations, and valvular disease. Interestingly, 4 (8%) patients in the Radboudumc registry reported arrhythmias without CHD, including one atrial fibrillation (AF), two with supraventricular tachycardias, and one with non-sustained ventricular tachycardia. The GenIDA registry reported one patient with AF and another with chronic ectopic atrial tachycardia (AT). In total, atrial tachyarrhythmias were noted in six young KS patients (6/213 or 3%) with at least four (three AF and one AT) without structural heart disease.

CONCLUSION

In addition to a high prevalence of CHD, evolving data reveal early-onset atrial tachyarrhythmias in young KS patients, including AF, even in the absence of structural heart disease.

Kleefstra Syndrome-Dental Manifestations and Needs: A Case Report with a Literature Review

Kleefstra syndrome (KS) is a rare genetic disorder (prevalence < 1/1 000 000) characterised by autistic spectrum disorder (ASD), childhood hypotonia, and seizures. A typical facial appearance includes microcephaly, arched eyebrows, synophrism, hypertelorism, a short nose, midface hypoplasia, prognathism, and tongue protrusion. This case report presents a 19-year-old female with KS from a dentist's perspective. The patient demonstrates limited mouth opening with a slight deviation of the mandible on the left side. The mandibular prognathism and anterior open bite are visible. A generalised inflammatory gingival enlargement is most likely a response to local irritants like plaque and calculus but is enhanced by the patient's mouth breathing habit. Also, the tongue is unusually large-macroglossia. Dental anomalies were diagnosed by digital panoramic radiograph, including dilaceration of the maxillary left second premolar and taurodontism. The patient was qualified to be treated under general anaesthesia with multiple extractions, restorations, hygienisation procedures, and tooth remineralisation. This individual should also be considered for orthodontic treatment and an eventual tongue reduction procedure. In the case of KS, multidisciplinary cooperation as well as frequent dental check-ups with fluoride prophylaxis are recommended. Unfortunately, dental treatment is still not an integral part of taking care of disabled children and youth with rare diseases.

Heterozygous NOTCH1 deletion associated with variable congenital heart defects

Pathogenic heterozygous variants in the NOTCH1 gene are known to be associated with both left and right-sided congenital cardiac anomalies with strikingly incomplete penetrance and variable phenotypic expressivity. De novo NOTCH1 whole gene deletion has been reported rarely in the literature and its association with cardiac defects is less well established. Here, we report four cases of NOTCH1 gene deletion from two families associated with a spectrum of congenital heart defects from bicuspid aortic valve to complex cardiac anomalies. This is the first description of a familial NOTCH1 deletion, showing apparently high penetrance, which may be unique to this mechanism of disease. Immunohistochemical staining of cardiac tissue demonstrated reduced levels of NOTCH1 expression in both the left and right ventricular outflow tracts. These cases suggest that haploinsufficiency caused by NOTCH1 gene deletion is associated with both mild and severe cardiac defects, similar to those caused by pathogenic variants in the gene, but with apparently higher, if not complete, penetrance.

MLPA analysis of 32 foetuses with a congenital heart defect and 1 foetus with renal defects - pilot study. The significant frequency rate of presented pathological CNV

AIMS

The aim of this retrospective study was to determine the detection rate of the pathogenic copy number variants (CNVs) in a cohort of 33 foetuses - 32 with CHD (congenital heart defects) and 1 with kidney defect, after exclusion of common aneuploidies (trisomy 13, 18, 21, and monosomy X) by karyotyping, Multiplex ligation - dependent probe amplification (MLPA) and chromosomal microarray analysis (CMA). We also assess the effectivity of MLPA as a method of the first tier for quick and inexpensive detection of mutations, causing congenital malformations in foetuses.

METHODS

MLPA with probe mixes P070, P036 - Telomere 3 and 5, P245 - microdeletions, P250 - DiGeorge syndrome, and P311 - CHD (Congenital heart defects) was performed in 33 samples of amniotic fluid and chorionic villi. CMA was performed in 10 relevant cases.

RESULTS

Pathogenic CNVs were found in 5 samples: microdeletions in region 22q11.2 (≈2 Mb) in two foetuses, one distal microdeletion of the 22q11.2 region containing genes LZTR1, CRKL, AIFM3 and SNAP29 (≈416 kb) in the foetus with bilateral renal agenesis, 8p23.1 (3.8 Mb) microdeletion syndrome and microdeletion in area 9q34.3 (1.7 Mb, Kleefstra syndrome). MLPA as an initial screening method revealed unambiguously pathogenic CNVs in 15.2 % of samples.

CONCLUSION

Our study suggests that MLPA and CMA are a reliable and high-resolution technology and should be used as the first-tier test for prenatal diagnosis of congenital heart disease. Determination of the cause of the abnormality is crucial for genetic counselling and further management of the pregnancy.

Anesthetic Management of an Infant With Kleefstra Syndrome During Direct Laryngoscopy and Rigid Bronchoscopy: A Case Report

Kleefstra syndrome (KS) is an autosomal dominant disorder caused by a chromosomal deletion at 9q34.3 resulting in pathogenic variants of the gene that codes for the enzyme, euchromatin histone methyltransferase 1 (EHMT1). KS is a rare, yet clinically relevant congenital disorder for anesthesiologists because of its potential for cardiac and craniofacial involvement. We present a 3-month-old patient with KS who required anesthetic care for diagnostic laryngoscopy and rigid bronchoscopy. The end-organ effects of KS are reviewed and our anesthetic care presented.

Shone's complex in a patient with chromosome 9q34.3 deletion (Kleefstra syndrome)

Kleefstra syndrome (chromosome 9q34.3 deletion) is a rare genetic disorder with less than 110 patients reported till date. We report a 4-month-old Caucasian girl with Kleefstra syndrome and Shone's complex, an association which has not been previously reported. Surgical planning for patients with Kleefstra syndrome and complex CHD can pose challenges due to an uncertain natural history and a risk of post-operative pulmonary hypertension.

Identification of De Novo and Rare Inherited Copy Number Variants in Children with Syndromic Congenital Heart Defects

Congenital heart defects (CHDs) are the most common birth defects in neonatal life. CHDs could be presented as isolated defects or associated with developmental delay (DD) and/or other congenital malformations. A small proportion of cardiac defects are caused by chromosomal abnormalities or single gene defects; however, in a large proportion of cases no genetic diagnosis could be achieved by clinical examination and conventional genetic analysis. The development of genome wide array-Comparative Genomic Hybridization technique (array-CGH) allowed for the detection of cryptic chromosomal imbalances and pathogenic copy number variants (CNVs) not detected by conventional techniques. We investigated 94 patients having CHDs associated with other malformations and/or DD. Clinical examination and Echocardiography was done to all patients to evaluate the type of CHD. To investigate for genome defects we applied high-density array-CGH 2 × 400K (41 patients) and CGH/SNP microarray 2 × 400K (Agilent) for 53 patients. Confirmation of results was done using Fluorescent in situ hybridization (FISH) or qPCR techniques in certain cases. Chromosomal abnormalities such as trisomy 18, 13, 21, microdeletions: del22q11.2, del7q11.23, del18 (p11.32; p11.21), tetrasomy 18p, trisomy 9p, del11q24-q25, add 15p, add(18)(q21.3), and der 9, 15 (q34.2; q11.2) were detected in 21/94 patients (22%) using both conventional cytogenetics methods and array-CGH technique. Cryptic chromosomal anomalies and pathogenic variants were detected in 15/73 (20.5%) cases. CNVs were observed in a large proportion of the studied samples (27/56) (48%). Clustering of variants was observed in chromosome 1p36, 1p21.1, 2q37, 3q29, 5p15, 7p22.3, 8p23, 11p15.5, 14q11.2, 15q11.2, 16p13.3, 16p11.2, 18p11, 21q22, and 22q11.2. CGH/SNP array could detect loss of heterozygosity (LOH) in different chromosomal loci in 10/25 patients. Array-CGH technique allowed for detection of cryptic chromosomal imbalances that could not be detected by conventional cytogenetics methods. CHDs associated with DD/congenital malformations presented with a relatively high rate of cryptic chromosomal abnormalities. Clustering of CNVs in certain genome loci needs further analysis to identify candidate genes that may provide clues for understanding the molecular pathway of cardiac development.

Cytogenomic Aberrations in Congenital Cardiovascular Malformations

Congenital cardiovascular malformations are the most common birth defects, with a complex multifactorial etiology. Genetic factors play an important role, illuminated by numerous cytogenetically visible abnormalities, as well as submicroscopic genomic imbalances affecting critical genomic regions in the affected individuals. Study of rare families with Mendelian forms, as well as emerging next-generation sequencing technologies have uncovered a multitude of genes relevant for human congenital cardiac diseases. It is clear that the complex embryology of human cardiac development, with an orchestrated interplay of transcription factors, chromatin regulators, and signal transduction pathway molecules can be easily perturbed by genomic imbalances affecting dosage-sensitive regions. This review focuses on chromosomal abnormalities contributing to congenital heart diseases and underscores several genomic disorders linked to human cardiac malformations in the last few decades.