Monosomy 18p

Lessons learned from 64,071 embryos subjected to PGT for aneuploidies: results, recurrence pattern and indications analysis

RESEARCH QUESTION

What is the influence of biological, technical and clinical factors on embryo outcomes in preimplantation genetic testing for aneuploidies (PGT-A) and what is the recurrence pattern?

DESIGN

This retrospective study included 64,071 embryos undergoing PGT-A in the same laboratory between 2011 and 2019. Biopsies were performed at the day 3 embryo stage (48.32%) or blastocyst stage (51.70%). Advanced maternal age (AMA) was the main indication (65.62%).

RESULTS

The aneuploidy rate was 67.75%, higher in women aged over 35 years than in women aged 35 years or less (71.76% versus 47.44%), and higher in day 3 embryo versus blastocyst biopsies (77.51% versus 58.62%). The trisomy:monosomy ratio was 1.01 for blastocysts versus 0.84 for day 3 embryos. Trisomy 21 was present in 4.9% of embryos. In aneuploid embryos, the probability of having one or more involved chromosomes followed a decreasing exponential pattern. The probability of an embryo being euploid was constant at around 30% (40% in blastocysts, 20% in day 3 embryos). The cumulative probability of having one or more euploid embryos after 10 biopsied embryos was 94.79% in blastocysts and 80.61% in day 3 embryos. AMA was associated with a much higher aneuploidy rate than all other indications, which among them had similar aneuploidy rate and chromosomal involvement.

CONCLUSIONS

There is a considerably lower aneuploidy rate in blastocysts than day 3 embryos, which is most notable for monosomies. While AMA shows an increased aneuploidy rate and a specific chromosomal pattern of involvement, the remaining indications showed a similar aneuploidy rate and chromosomal pattern. Even after producing many consecutive aneuploid embryos, the possibility of obtaining a euploid embryo is not negligible.

Monozygotic triplets with juvenile-onset autoimmunity and 18p microdeletion involving PTPRM

Abnormal gene dosage from copy number variants has been associated with susceptibility to autoimmune disease. This includes 18p deletion syndrome, a chromosomal disorder with an estimated prevalence of 1 in 50,000 characterized by intellectual disability, facial dysmorphology, and brain abnormalities. The underlying causes for autoimmune manifestations associated with 18p deletions, however, remain unknown. Our objective was to investigate a distinctive case involving monozygotic triplets concordant for developmental delay, white matter abnormalities, and autoimmunity, specifically juvenile-onset Graves' thyroiditis. By chromosomal microarray analysis and whole genome sequencing, we found the triplets to carry a de novo interstitial 5.9 Mb deletion of chromosome 18p11.31p11.21 spanning 19 protein-coding genes. We conducted a literature review to pinpoint genes affected by the deletion that could be associated with immune dysregulation and identified PTPRM as a potential candidate. Through dephosphorylation, PTPRM serves as a negative regulator of STAT3, a key factor in the generation of Th17 cells and the onset of specific autoimmune manifestations. We hypothesized that PTPRM hemizygosity results in increased STAT3 activation. We therefore performed assays investigating PTPRM expression, STAT3 phosphorylation, Th1/Th2/Th17 cell fractions, Treg cells, and overall immunophenotype, and in support of the hypothesis, our investigations showed an increase in cells with phosphorylated STAT3 and higher levels of Th17 cells in the triplets. We propose that PTPRM hemizygosity can serve as a contributing factor to autoimmune susceptibility in 18p deletion syndrome. If confirmed in unrelated 18p/PTPRM deletion patients, this susceptibility could potentially be treated by targeted inhibition of IL-17.

Prenatal detection of distal 18p deletion by chromosomal microarray analysis: Three case reports and literature review

BACKGROUND

Chromosome 18p deletion syndrome is caused by total or partial deletion of the short arm of chromosome 18 and associated with cognitive impairment, growth retardation and mild facial dysmorphism. However, most studies on the genotype-phenotype correlations in the 18p region are diagnosed postnatally. Prenatal reports involving 18p deletions are limited.

METHODS

Three pregnant women opted for invasive prenatal testing due to noninvasive prenatal testing indicating high risk for chromosome 18 abnormalities. Karyotypic analysis and chromosomal microarray analysis (CMA) were performed simultaneously. The pregnancy outcomes for all cases were followed up. Meanwhile, we also made a literature review on prenatal phenotypes of 18p deletions.

RESULTS

G-banding analysis showed that 2 fetuses presented abnormal karyotypes: 45,XN,der(18)t(18;21)(p11; q11),-21 (case 2) and 46,XN,18p- (case 3). The karyotype of case 1 was normal. Meanwhile, CMA detected 4.37 Mb (case 1), 7.26 Mb (case 2) and 14.97 Mb (case 3) deletions in chromosome 18p region. All 3 pregnancies were terminated finally according to genetic counseling based upon abnormal CMA results.

CONCLUSION

Prenatal diagnosis of 18p deletion syndrome is full of challenges due to the phenotypic diversity, incomplete penetrance and lack of prenatal phenotypes. Increased nuchal translucency and holoprosencephaly are common prenatal phenotypes of distal 18p deletion. For fetuses carrying 18p deletions with atypical sonographic phenotypes, noninvasive prenatal testing could be adopted as an effective approach.

Prenatal diagnosis of 18p deletion and 8p trisomy syndrome: literature review and report of a novel case

18p deletion syndrome constitutes one of the most frequent autosomal terminal deletion syndromes, affecting one in 50,000 live births. The syndrome has un-specific clinical features which vary significantly between patients and may overlap with other genetic conditions. Its prenatal description is extremely rare as the fetal phenotype is often not present during pregnancy. Trisomy 8p Syndrome is characterized by heterogenous phenotype, with the most frequent components to be cardiac malformation, developmental and intellectual delay. Its prenatal diagnosis is very rare due to the unspecific sonographic features of the affected fetuses. We present a very rare case of a fetus with multiple anomalies diagnosed during the second trimester whose genomic analysis revealed a 18p Deletion and 8p trisomy Syndrome. This is the first case where this combination of DNA mutations has been described prenatally and the second case in general. The presentation of this case, as well as the detailed review of all described cases, aim to expand the existing knowledge regarding this rare condition facilitating its diagnosis in the future.

18p Deletion Syndrome With a 45, XY, t (14;18) (p11.1; p11.1), Karyotype

Monosomy 18p deletion syndrome is a rare genetic disorder. We present an uncommon case of 18p deletion syndrome originating from a unique translocation between chromosomes 14 and 18 in an 11-year-old Saudi male, manifesting various clinical features. This case highlights the importance of understanding the genotype-phenotype correlations of 18p deletion syndrome to aid in the early recognition of the syndrome for its effective diagnosis and management.

Live-born autosomal ring chromosomes at the Johns Hopkins Hospital Cytogenomics Laboratory: Case series-Spanning 52 years of experience in a single center

Ring chromosomes (RCs) are a structural aberration that can be tolerated better in acrocentric or gonosomal chromosomes. Complete RCs arise from telomere-telomere fusions. Alternatively, genomic imbalances corresponding to the ends of the chromosomal arms can be seen with RC formation. RCs are unstable in mitosis, result in mosaicism, and are associated with a "ring syndrome," which presents with growth and development phenotypes and differs from those features more frequently observed with pure terminal copy number changes. Due to variability in mosaicism, size, and genomic content, clear genotype-phenotype correlations may not always be possible. Given the rarity of RCs, this historical data is invaluable. We performed a retrospective review of individuals bearing RCs to investigate the incidence in our laboratory. This work details the methods and features seen in association with twenty-three autosomal RCs. In decreasing order, the most frequently seen autosomal RCs were 18, 22, 4, 13, 17, and 9. The additional cases detail clinical and cytogenomic events similar to those reported in RCs. As methodologies advance, insights may be gleaned from following up on these cases to improve genotype-phenotype correlations and understand the cryptic differences or other predisposing factors that lead to ring formation and development.

Chromosome analysis of foetal tissue from 1903 spontaneous abortion patients in 5 regions of China: a retrospective multicentre study

BACKGROUND

Abnormal foetal tissue chromosome karyotypes are one of the important pathogenic factors for spontaneous abortion (SA). To investigate the age and abnormal foetal karyotypes of 1903 couples who experienced SA.

METHODS

A retrospective multicentre study collected age and foetal tissue karyotypes CNV-seq data of 1903 SA couples from 6 hospitals in 5 regions from January 2017 to March 2022. The distribution and correlation of abnormal foetal tissue karyotypes were evaluated by using regions and age.

RESULTS

In our study, 1140 couples (60.5% of the total) had abnormal foetal tissue chromosome karyotypes in all regions. We found that there were differences in the number of abnormal foetal tissue chromosome karyotypes, of which the incidence of trisomy was higher. At the same time, the populations situated in the eastern region had a more triploid (15.5%) distribution, trisomy (58.1%) in the southern region, mosaicism (14.8%) and microduplication (31.7%) in the southwestern region, microdeletion (16.7%) in the northern region. There are variances across areas, and it is more common in the north. The incidence risk of prenatal chromosomal abnormalities varied according to age group.

CONCLUSION

The findings of this study suggest that the karyotypes of patients with abnormal foetal tissue chromosome abortion in different regions were different. Meanwhile, patients ≥ 35 years old had a higher risk of abnormal foetal tissue chromosome abortion.

The molecular mechanisms of recombinant chromosome 18 with parental pericentric inversions and a review of the literature

Chromosomal rearrangements mostly result from non-allelic homologous recombination mediated by low-copy repeats (LCRs) or segmental duplications (SDs). Recent studies on recombinant chromosome 18 (rec (18)) have focused on diagnoses and clinical phenotypes. We diagnosed two cases of prenatal rec (18) and identified precise breakpoint intervals using karyotype and chromosomal microarray analyses. We analyzed the distribution characteristics of breakpoint repetitive elements to infer rearrangement mechanisms and reviewed relevant literature to identify genetic trends. Among the 12 families with 25 pregnancies analyzed, 68% rec (18), 24% spontaneous abortions, and 8% normal births were reported. In the 17 rec (18) cases, 65% presented maternal origin and 35% were paternal. Short-arm breakpoints at p11.31 were reported in 10 cases, whereas the long-arm breakpoints were located at q21.3 (6 cases) and q12 (4 cases). Breakpoints of pericentric inversions on chromosome 18 are concentrated in p11.31, q21.3, and q12 regions. Rearrangements at 18p11.31 are non-recurrent events. ALUs, LINE1s, and MIRs were enriched at the breakpoint regions (1.85 to 3.42-fold enrichment over the entire chromosome 18), while SDs and LCRs were absent. ALU subfamilies had sequence identities of 85.94% and 83.01% between two pair breakpoints. Small repetitive elements may mediate recombination-coupled DNA repair processes, facilitating rearrangements on chromosome 18. Maternal inversion carriers are more prone to abnormal recombination in prenatal families with rec (18). Recombinant chromosomes may present preferential segregation during gamete formation.

18p Deletion Syndrome Originating from Rare Unbalanced Whole-Arm Translocation between Chromosomes 13 and 18: A Case Report and Literature Review

18p deletion (18p-) syndrome is a rare chromosome abnormality that has a wide range of phenotypes, with short stature, intellectual disability, and facial dysmorphism being the main clinical features. Here, we report the first case in Korea of a 16-year-old male adolescent with 18p- syndrome resulting from de novo unbalanced whole-arm translocation between chromosomes 13 and 18 (45, XY, der(13;18)(q10:q10)). Three rare clinical findings were discovered that had not been reported in the previous literature; morbid obesity without other hormonal disturbances, rib cage deformity leading to the direct compression of the liver, and lumbar spondylolisthesis at the L5-S1 level. This case expands the phenotypic spectrum of 18p- syndrome and highlights the importance of considering chromosomal analysis, since this syndrome can be easily overlooked in a clinical setting, especially without distinctive symptoms of other organs, due to its nonspecific but typical features of short stature and mild intellectual disability with a mildly dysmorphic face. Moreover, since not all cases of 18p- syndrome with unbalanced translocation (13;18) show the same phenotype, multidisciplinary examinations and follow-up seem to be important to monitor evolving and developing clinical manifestations and to predict prognosis in advance associated with the specific genes of 18p breakpoint regions.

Presentation of an Infant with Chromosome 18p Deletion Syndrome and Asymmetric Septal Hypertrophy

The frequency of 18p deletion syndrome is estimated to be ∼1/50,000 live births and is more commonly associated with certain clinical features including short stature, intellectual disability, and facial dysmorphism. Physical examination of our patient revealed a short stature, intellectual disability, facial dysmorphism (microcephaly, ptosis, epicanthus, low nasal bridge, protruding ears, long philtrum, and thin lips), and clinodactyly of the fifth finger. The peripheral karyotype was 46, XX, del (18) (p11.32p11.2). DNA microarray analysis revealed a de novo 13.9-Mb deletion at 18p11.32p.11.21. Echocardiography revealed asymmetric septal hypertrophy. Congenital cardiac abnormalities are present very rarely in this syndrome. This finding suggests that one locus or loci that play a role in cardiac development is located in this chromosomal region. Although rare, cardiac hypertrophies should be kept in mind when evaluating a patient with phenotypic anomalies and genetic results compatible with an 18p deletion syndrome.

Prenatal diagnosis of middle interhemispheric variant of holoprosencephaly: Report of two cases

Holoprosencephaly ranges in severity based on the degree of anatomic abnormality. Middle interhemispheric variant of holoprosencephaly is a less common and often milder variant that has the characteristic sonographic findings of an absent cavum septum pellucidum and a single fused ventricle. This subtype may be associated with genetic conditions that have not been well-described in the literature. We present two cases of middle interhemispheric variant of holoprosencephaly diagnosed on fetal ultrasound.

Genetic syndromes with diabetes: A systematic review

Previous reviews and clinical guidelines have identified 10-20 genetic syndromes associated with diabetes, but no systematic review has been conducted to date. We provide the first comprehensive catalog for syndromes with diabetes mellitus. We conducted a systematic review of MEDLINE, Embase, CENTRAL, PubMed, OMIM, and Orphanet databases for case reports, case series, and observational studies published between 1946 and January 15, 2020, that described diabetes mellitus in adults and children with monogenic or chromosomal syndromes. Our literature search identified 7,122 studies, of which 160 fulfilled inclusion criteria. Our analysis of these studies found 69 distinct diabetes syndromes. Thirty (43.5%) syndromes included diabetes mellitus as a cardinal clinical feature, and 56 (81.2%) were fully genetically elucidated. Sixty-three syndromes (91.3%) were described more than once in independent case reports, of which 59 (93.7%) demonstrated clinical heterogeneity. Syndromes associated with diabetes mellitus are more numerous and diverse than previously anticipated. While knowledge of the syndromes is limited by their low prevalence, future reviews will be needed as more cases are identified. The genetic etiologies of these syndromes are well elucidated and provide potential avenues for future gene identification efforts, aid in diagnosis and management, gene therapy research, and developing personalized medicine treatments.

[Congenital hypopituitarism with monosomy of chromosome 18]

Congenital hypopituitarism is a rare disease. It can be caused by isolated inborn defects of the pituitary, gene mutations (PROP1, PIT1), and chromosomal abnormalities.Deletions of chromosome 18 (De Grouchy syndrome types 1 and 2) are a group of rare genetic diseases with a frequency of 1:50,000. Hypopituitarism in these syndromes is detected in from 13 to 56% of cases and depends on the size and location of the deleted segment.We have described a series of clinical cases of patients with congenital hypopituitarism due to deletions in chromosome 18. All children had a characteristic dysmorphic features and delayed mental and speech development. Within first months of life, patients developed muscular hypotension, dysphagia, and respiratory disorders. The patients had various congenital malformations in combination with hypopituitarism (isolated growth hormone deficiency and multiple pituitaryhormone deficiencies). In the neonatal period, there were the presence of hypoglycemia in combination with cholestasis.Hormone replacement therapy led to rapid relief of symptoms.Сhromosomal microarray analysis in 2 patients allowed us to identify exact location of deleted area and deleted genes and optimize further management for them.

Human Chromosome 18 and Acrocentrics: A Dangerous Liaison

The presence of thousands of repetitive sequences makes the centromere a fragile region subject to breakage. In this study we collected 31 cases of rearrangements of chromosome 18, of which 16 involved an acrocentric chromosome, during genetic screening done in three centers. We noticed a significant enrichment of reciprocal translocations between the centromere of chromosome 18 and the centromeric or pericentromeric regions of the acrocentrics. We describe five cases with translocation between chromosome 18 and an acrocentric chromosome, and one case involving the common telomere regions of chromosomes 18p and 22p. In addition, we bring evidence to support the hypothesis that chromosome 18 preferentially recombines with acrocentrics: (i) the presence on 18p11.21 of segmental duplications highly homologous to acrocentrics, that can justify a NAHR mechanism; (ii) the observation by 2D-FISH of the behavior of the centromeric regions of 18 respect to the centromeric regions of acrocentrics in the nuclei of normal subjects; (iii) the contact analysis among these regions on published Hi-C data from the human lymphoblastoid cell line (GM12878).

The genotype and phenotype of chromosome 18p deletion syndrome: Case series

RATIONALE

The chromosome 18p deletion syndrome is a syndrome with a deletion of all or a portion of the short arm of the chromosome 18. The phenotypes of the chromosome 18p deletion syndrome vary widely among individuals due to differences in size and breakpoints and the involved genes on the deletions. Given the varied and untypical clinical presentation of this syndrome, the prenatal diagnosis of the syndrome still presents as a challenge.

PATIENT CONCERNS

We described 4 China cases with different chromosomal breakpoints. In case 1, a woman who with mild phenotypes gave birth to a severely deformed fetus. Three other cases were for prenatal diagnosis. Their phenotypes are the increased nuchal translucency (INT) and the noninvasive prenatal testing (NIPT) indicated deletions on the chromosome 18p and severe hydronephrosis respectively.

DIAGNOSIS

The 4 cases were diagnosed with chromosome 18p deletion syndrome through karyotype analysis and array-based comparative genomic hybridization (array-CGH).

INTERVENTIONS

Karyotype analysis and array-based comparative genomic hybridization were used to analyze the abnormal chromosome.

OUTCOMES

Case 1 and case 2 revealed 11.51 and 12.39 Mb deletions in 18p11.32p11.21. Case 3 revealed 7.1 Mb deletions in 18p11.3218p11.23. Case 4 revealed 9.9 Mb deletions in 18p11.3218p11.22.

LESSONS

In our report, we are the first to report that mother and progeny who have the same chromosomal breakpoint have different phenotypes, significantly. In addition, we found a new phenotype of chromosome 18p deletion syndrome in fetus, which can enrich the phenotypes of this syndrome in the prenatal diagnosis. Finally, we demonstrate that the individuals with different chromosomal breakpoints of 18p deletion syndrome have different phenotypes. On the other hand, the individuals with the same chromosomal breakpoints of 18p deletion syndrome may also have remarkably different phenotypes.

Mosaic ring chromosome 18 in a Chinese child with epilepsy: a case report and review of the literature

BACKGROUND

Ring chromosome 18 (r[18]) is a rare syndrome in which one or both ends of chromosome 18 are lost and the remaining chromosome rejoins to form ring-shaped figures. It is characterized by developmental delay/cognitive disability, facial dysmorphisms, and immunological problems. The phenotype associated with epilepsy is rare and has not yet been reported in China.

METHODS

We report herein the case of a 12-year-old Chinese girl who presented with typical facial dysmorphisms, developmental delay, cognitive disability, hyperactivity, and epilepsy and discuss the clinical features of r(18) syndromes through comparison with previously described cases worldwide.

RESULTS

We describe the characteristics of all seizures that have been reported in these cases and propose that the appearance of epilepsy in r(18) patients may be associated with the abnormality of chromosome karyotypes. Further studies are warranted to confirm this.

Case report of a novel phenotype in 18q deletion syndrome

The latest decades are characterized by an enormous progression in the field of human genetics. In consequences, for various phenotypic manifestations, genetic testing could identify a specific underlying cause. An estimated incidence for all types of 18q deletions is one in 55 000 births predominant on females. About 94% of cases with 18q deletion syndrome appearance are de novo, and the remaining 6% are the inherited from a parent carrying a balanced chromosomal translocation. We present the case of a 35-year-old female who was admitted in our Unit for a second ultrasound opinion after being diagnosed at the second trimester scan at gestational age of 21 weeks of pregnancy with multiple brain and heart malformations, having the recommendation for fetal magnetic resonance imaging (MRI). Further investigations included genetic analysis and pathological examination. Major malformations diagnosed and confirmed were agenesis of the corpus callosum, ventriculomegaly with dilated fourth ventricle, partial agenesis of vermis, bilateral anophthalmia with wide nasal base and left cleft lip. Additional, cardiac malformation, with an important ventricular septal defect and overriding aorta were noted. The results of the microarray analysis showed an abnormal fetal karyotype with a loss of 30.5 basis identified in the long arm of chromosome 18. Although most of the cases of 18q deletion are sporadically or de novo, could be cases where the possible existing syndromes can be inherited from a healthy or mild affected parent. Therefore, in order to establish the recurrence risk, parental karyotypes are recommended.

Discovery of a Chinese familial deletion 18p syndrome due to a false positive result on noninvasive prenatal testing

Clinical manifestations of deletion 18p syndrome vary a lot, which makes it easily overlooked in the clinical practice. Familial transmission of deletion 18p syndrome is rare. We report a Chinese familial deletion 18p syndrome, which was diagnosed by anatomizing the underlying reason for the discrepancy between noninvasive prenatal testing (NIPT) and prenatal diagnosis. A 35-year-old pregnant woman was recruited to our center owing to the abnormal NIPT result with a high risk of chromosome 18 monosomy. However, the karyotype of the fetus was normal after amniocentesis. Further analysis indicated that the pregnant woman herself had an abnormal karyotype of 46,XX,del(18)(p11.2), (arr18p11.32p11.21[136,227-15,099,116]×1) and her first 12-year-old son had got the same deletion of 18p as her. A distinct phenotype variability was noted although they share identical deletion. We consider that adequate clinical genetic counseling is vital for women with adverse pregnancy history before getting pregnant. Maternal CNVs may be one of the main causes of the false-positive result on NIPT. NIPT, especially extended NIPT may provide extra valuable evidence when used as routine prenatal screening method.

A scoping review and proposed workflow for multi-omic rare disease research

BACKGROUND

Patients with rare diseases face unique challenges in obtaining a diagnosis, appropriate medical care and access to support services. Whole genome and exome sequencing have increased identification of causal variants compared to single gene testing alone, with diagnostic rates of approximately 50% for inherited diseases, however integrated multi-omic analysis may further increase diagnostic yield. Additionally, multi-omic analysis can aid the explanation of genotypic and phenotypic heterogeneity, which may not be evident from single omic analyses.

MAIN BODY

This scoping review took a systematic approach to comprehensively search the electronic databases MEDLINE, EMBASE, PubMed, Web of Science, Scopus, Google Scholar, and the grey literature databases OpenGrey / GreyLit for journal articles pertaining to multi-omics and rare disease, written in English and published prior to the 30th December 2018. Additionally, The Cancer Genome Atlas publications were searched for relevant studies and forward citation searching / screening of reference lists was performed to identify further eligible articles. Following title, abstract and full text screening, 66 articles were found to be eligible for inclusion in this review. Of these 42 (64%) were studies of multi-omics and rare cancer, two (3%) were studies of multi-omics and a pre-cancerous condition, and 22 (33.3%) were studies of non-cancerous rare diseases. The average age of participants (where known) across studies was 39.4 years. There has been a significant increase in the number of multi-omic studies in recent years, with 66.7% of included studies conducted since 2016 and 33% since 2018. Fourteen combinations of multi-omic analyses for rare disease research were returned spanning genomics, epigenomics, transcriptomics, proteomics, phenomics and metabolomics.

CONCLUSIONS

This scoping review emphasises the value of multi-omic analysis for rare disease research in several ways compared to single omic analysis, ranging from the provision of a diagnosis, identification of prognostic biomarkers, distinct molecular subtypes (particularly for rare cancers), and identification of novel therapeutic targets. Moving forward there is a critical need for collaboration of multi-omic rare disease studies to increase the potential to generate robust outcomes and development of standardised biorepository collection and reporting structures for multi-omic studies.

A case of prenatal diagnosis of 18p deletion syndrome following noninvasive prenatal testing

Background

Chromosome 18p deletion syndrome is a disease caused by the complete or partial deletion of the short arm of chromosome 18, there were few cases reported about the prenatal diagnosis of 18p deletion syndrome. Noninvasive prenatal testing (NIPT) is widely used in the screening of common fetal chromosome aneuploidy. However, the segmental deletions and duplications should also be concerned. Except that some cases had increased nuchal translucency or holoprosencephaly, most of the fetal phenotype of 18p deletion syndrome may not be evident during the pregnancy, 18p deletion syndrome was always accidentally discovered during the prenatal examination.

Case presentations

In our case, we found a pure partial monosomy 18p deletion during the confirmation of the result of NIPT by copy number variation sequencing (CNV-Seq). The result of NIPT suggested that there was a partial or complete deletion of X chromosome. The amniotic fluid karyotype was normal, but result of CNV-Seq indicated a 7.56 Mb deletion on the short arm of chromosome 18 but not in the couple, which means the deletion was de novo deletion. Finally, the parents chose to terminate the pregnancy.

Conclusions

To our knowledge, this is the first case of prenatal diagnosis of 18p deletion syndrome following NIPT.NIPT combined with ultrasound may be a relatively efficient method to screen chromosome microdeletions especially for the 18p deletion syndrome.

Two Distinctively Rare Syndromes in a Case of Primary Amenorrhea: 18p Deletion and Mayer-Rokitansky-Kuster-Hauser Syndromes

Mayer-Rokitansky-Kuster-Hauser (MRKH) syndrome and 18p deletion syndrome, two genetic disorders having distinct genetic etiologies, have an exceedingly rare likelihood of coexistence. Vaginal agenesis or MRKH syndrome, the developmental failure of Mullerian ductal system-derived structures in a genotypic female fetus (46, XX), leads to congenital absence of uterus and vagina in variable degree. The 18p deletion syndrome is a rare chromosomal disorder, characterized by dysmorphic features, stunted growth, and mental retardation, which is caused by deletion of a part or all of the short arm of chromosome 18. A detailed evaluation of primary amenorrhea in a 16-year-old girl yielded both MRKH syndrome and 18p deletion syndrome. Extensive literature search could not identify any reported case bearing this combination of syndromes. This case presentation and review emphasizes on the importance of karyotyping in MRKH patients having atypical features.

Cytogenetic, Molecular, and Phenotypic Characterization of a Patient with de novo Derivative Chromosome 18 and Review of the Literature

We present a patient with a de novo derivative chromosome 18 which includes a terminal deletion of 18p and a terminal duplication of 18q accompanied by a cryptic duplication of 18p. The girl had mild dysmorphic features such as micro-retrognathia, upslanted palpebral fissures, bilateral epicanthus, high palate, low-set ears, short neck, and full cheeks. She also had an H-type tracheoesophageal fistula which required surgery. Her cognitive and motor skills were delayed. Karyotype analysis showed an additional segment on the short arm of chromosome 18. Chromosomal microarray revealed a 7.3-Mb terminal loss from 18p11.32 to 18p11.23, a 22.2-Mb terminal gain from 18q21.31 to 18q23, and a 3.9-Mb interstitial gain from 18p11.22 to 18p11.21. We hypothesize that the mother has gonadal mosaicism for normal chromosome 18, der(18)dup(p11.22p11.21), and der(18)dup(p11. 22p11.21)inv(18)(p11.22q21.31), or both the terminal del/dup and the interstitial duplication occurred simultaneously.

Detection of a rare de novo 18p terminal deletion with inverted duplication in a Chinese pregnant woman

Background

The 18p terminal deletion with inverted duplication is an extremely rare chromosome structure abnormality and the common clinical manifestations include intellectual disability and speech delay, etc. Up to now, only three confirmed cases were reported in Europe, and here, for the first time in the Asian population, we report a case of de novo 18p inv‐dup‐del in a Chinese pregnant woman. This structural variation was accidentally discovered by the noninvasive prenatal testing (NIPT) during her prenatal examination.

Methods

Next generation sequencing (NGS) based copy number variations (CNVs) screening and karyotype analysis were performed to verify the type and heredity of the rearrangement, and the fluorescent in situ hybridization (FISH) analysis was also used to confirm the terminal deletion and inverted duplication.

Results

The patient has a de novo 18p11.31‐18p11.1 inverted duplication with a 6.2 Mb 18p terminal deletion. This rare chromosome imbalance, most likely caused by the U‐type exchange mechanism, resulted in the aberrant phenotype of mental disability, speech delay, seizure, and strabismus. However, the rearrangement was not inherited by her unborn child.

Conclusion

This report added a new type of variation to the spectrum of 18p terminal deletion with inverted duplication, and demonstrated that the maternal chromosome rearrangement discovered in NIPT should not just be consider as an interference factor but also a potential indicator of previously undiscovered pathogenic chromosome structure variations in pregnant women.

Prenatal diagnosis of de novo monosomy 18p deletion syndrome by chromosome microarray analysis: Three case reports

RATIONALE

Monosomy 18p deletion syndrome refers to a rare chromosomal disorder resulting from the part deletion of the short arm of chromosome 18. Prenatal diagnosis of de novo 18p deletion syndrome is a challenge due to its low incidence and untypical prenatal clinical presentation.

PATIENT CONCERNS

Three cases received amniocentesis due to increased nuchal translucency (INT), high risk for Down syndrome, and INT combined intrauterine growth retardation (IUGR), respectively.

DIAGNOSIS

The 3 cases were diagnosed with de novo monosomy 18p deletion syndrome by amniocentesis and chromosome microarray analysis (CMA).

INTERVENTIONS

Karyotype analysis and CMA were used to analyze the abnormal chromosome.

OUTCOMES

Case 1 and case 2 revealed 13.87 and 12.68 Mb deletions by array-CGH analysis, respectively. Case 3 revealed 6.9 Mb deletions in 18p11.32p11.31 and 7.5 Mb deletions in 18p11.23p11.21 by single nucleotide polymorphism array. All of the pregnancies were terminated due to the abnormal chromosome.

LESSONS

The fetal phenotype of monosomy 18p deletion syndrome shows great variability and may not be evident during the pregnancy. CMA may be served as an effective tool for the diagnosis of prenatal monosomy 18p deletion syndrome diagnosis.

Long contiguous stretches of homozygosity detected by chromosomal microarrays (CMA) in patients with neurodevelopmental disorders in the South of Brazil

Background

Currently, chromosomal microarrays (CMA) are recommended as first-tier test in the investigation of developmental disorders to examine copy number variations. The modern platforms also include probes for single nucleotide polymorphisms (SNPs) that detect homozygous regions in the genome, such as long contiguous stretches of homozygosity (LCSH) also named runs of homozygosity (ROH). LCHS are chromosomal segments resulting from complete or segmental chromosomal homozygosity, which may be indicative of uniparental disomy (UPD), consanguinity, as well as replicative DNA repair events, however also are common findings in normal populations. Knowing common LCSH of a population, which probably represent ancestral haplotypes of low-recombination regions in the genome, facilitates the interpretation of LCSH found in patients, allowing to prioritize those with possible clinical significance. However, population records of ancestral haplotype derived LCSH by SNP arrays are still scarce, particularly for countries such as Brazil where even for the clinic, microarrays that include SNPs are difficult to request due to their high cost.

Methods

In this study, we evaluate the frequencies and implications of LCSH detected by Affymetrix CytoScan® HD or 750 K platforms in 430 patients with neurodevelopmental disorders in southern Brazil. LCSH were analyzed in the context of pathogenic significance and also explored to identify ancestral haplotype derived LCSH. The criteria for considering a region as LCSH was homozygosis ≥3 Mbp on an autosome.

Results

In 95% of the patients, at least one LCSH was detected, a total of 1478 LCSH in 407 patients. In 2.6%, the findings were suggestive of UPD. For about 8.5% LCSH suggest offspring from first to fifth grade, more likely to have a clinical impact. Considering recurrent LCSH found at a frequency of 5% or more, we outline 11 regions as potentially representing ancestral haplotypes in our population. The region most involved with homozygosity was 16p11.2p11.1 (49%), followed by 1q21.2q21.3 (21%), 11p11.2p11.12 (19%), 3p21.31p21.2 (16%), 15q15 1q33p32.3 (12%), 2q11.1q12.1 (9%), 1p33p32.3 (6%), 20q11.21q11.23 (6%), 10q22.1q23.31 (5%), 6p22.2p22 (5%), and 7q11.22q11.23 (5%).

Conclusions

In this work, we show the importance and usefulness of interpreting LCSH in the results of CMA wich incorporate SNPs.

A case of de novo 18p deletion syndrome with panhypopituitarism

Deletion on the short arm of chromosome 18 is a rare disorder characterized by intellectual disability, growth retardation, and craniofacial malformations (such as prominent ears, microcephaly, ptosis, and a round face). The phenotypic spectrum is wide, encompassing a range of abnormalities from minor congenital malformations to holoprosencephaly. We present a case of a 2-year-old girl with ptosis, a round face, broad neck with low posterior hairline, short stature, and panhypopituitarism. She underwent ventilation tube insertion for recurrent otitis media with effusion. Brain magnetic resonance imaging showed an ectopic posterior pituitary gland and a shallow, small sella turcica with poor visualization of the pituitary stalk. Cytogenetic and chromosomal microarray analysis revealed a de novo deletion on the short arm of chromosome 18 (arr 18p11.32p11.21[136,227-15,099,116]x1). She has been treated with recombinant human growth hormone (GH) therapy since the age of 6 months after diagnosis of GH deficiency. Her growth rate has improved without any side effects from the GH treatment. This case expands the phenotypic spectrum of 18p deletion syndrome and emphasizes the positive impact of GH therapy on linear growth in this syndrome characterized by growth deficiency. Further studies are required to define the genotype-phenotype correlation according to size and loci of the deletion in 18p deletion syndrome and to predict prognosis.

A 13-year-old girl with 18p deletion syndrome presenting Turner syndrome-like clinical features of short stature, short webbed neck, low posterior hair line, puffy eyelids and increased carrying angle of the elbows

OBJECTIVE

We report a 13-year-old girl with 18p deletion syndrome presenting Turner syndrome-like clinical features.

CASE REPORT

A 13-year-old girl was referred for genetic counseling of Turner syndrome-like clinical features of short stature, short webbed neck, low posterior hair line, puffy eyelids and increased carrying angle of the elbows. The girl also had mild intellectual disability, psychomotor developmental delay, speech disorder, high-arched palate, hypertelorism and mid-face hypoplasia. Cytogenetic analysis of the girl revealed a karyotype of 46,XX,del(18) (p11.2). The parental karyotypes were normal. Array comparative genomic hybridization analysis on the DNA extracted from the peripheral blood revealed a 13.93-Mb deletion of 18p11.32-p11.21 or arr 18p11.32p11.21 (148,993-14,081,858) × 1.0 [GRCh37 (hg19)] encompassing 52 Online Mendelian Inheritance in Man (OMIM) genes including USP14, TYMS, SMCHD1, TGIF1, LAMA1, TWSG1, GNAL and PTPN2. Polymorphic DNA marker analysis revealed a maternal origin of the deletion.

CONCLUSION

Females with Turner syndrome-like clinical features in association with intellectual disability, facial dysmorphism and psychomotor developmental delay should be suspected of having chromosome deletion syndromes.

Molecular testing in holoprosencephaly

Holoprosencephaly (HPE) is a structural brain anomaly characterized by failure of the forebrain to separate during early embryogenesis. Both genetic and environmental etiologies of HPE have been discovered over the last three decades. Traditionally, the genetic workup for HPE has been a karyotype, chromosomal microarray, and/or Sanger sequencing of select genes. The recent increased availability of next-generation sequencing has changed the molecular diagnostic landscape for HPE, associating new genes with this disorder such as FGFR1. We conducted a systematic review of the medical literature for the molecular testing of HPE for studies published in the last 20 years. We also queried known commercial diagnostic laboratories and used information on their websites to construct a list of available commercial testing. Our group released its first recommendations in 2010 and this update incorporates the technology shifts and gene discoveries over the last decade. These recommendations provide a guide for genetic diagnosis of HPE, which is paramount for patients and their families for prognosis, treatment, and genetic counseling.

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.

Syndromes associated with holoprosencephaly

Holoprosencephaly (HPE) is partial or complete failure of the forebrain to divide into hemispheres and can be an isolated finding or associated with a syndrome. Most cases of HPE are associated with a syndrome and roughly 40%-60% of fetuses with HPE have trisomy 13 which is the most common etiology of HPE. Other syndromes associated with HPE include additional aneuploidies like trisomy 18 and single gene disorders such as Smith-Lemli-Opitz syndrome. There are a number of syndromes such as pseudotrisomy 13 which do not have a known molecular etiology; therefore, this review has two parts: syndromes with a molecular diagnosis and syndromes where the etiology is yet to be found. As most HPE is syndromic, this review provides a comprehensive list and description of syndromes associated with HPE that may be used as a differential diagnosis and starting point for evaluating individuals with HPE.

Genotype-Phenotype Analysis, Neuropsychological Assessment, and Growth Hormone Response in a Patient with 18p Deletion Syndrome

18p deletion syndrome is a rare chromosomal disease caused by deletion of the short arm of chromosome 18. By using cytogenetic and SNP array analysis, we identified a girl with 18p deletion syndrome exhibiting craniofacial anomalies, intellectual disability, and short stature. G-banding analysis of metaphase cells revealed an abnormal karyotype 46,XX,del(18)(p10). Further, SNP array detected a 15.3-Mb deletion at 18p11.21p11.32 (chr18:12842-15375878) including 61 OMIM genes. Genotype-phenotype correlation analysis showed that clinical manifestations of the patient were correlated with LAMA1, TWSG1, and GNAL deletions. Her neuropsychological assessment test demonstrated delay in most cognitive functions including impaired mathematics, linguistic skills, visual motor perception, respond speed, and executive function. Meanwhile, her integrated visual and auditory continuous performance test (IVA-CPT) indicated a severe comprehensive attention deficit. At age 7 and 1/12 years, her height was 110.8 cm (-2.5 SD height for age). Growth hormone (GH) treatment was initiated. After 27 months treatment, her height was increased to 129.6 cm (-1.0 SD height for age) at 9 and 4/12 years, indicating an effective response to GH treatment.

A case of 18p deletion syndrome after blepharoplasty

Objective

The deletion of the short arm of chromosome 18 is thought to be one of the rare chromosomal aberrations. Here, we report a case to review this disease.

Case report

The proband is a five-and-a-half-year-old girl who has had phenotypes manifested mainly by ptosis, broad face, broad neck with low posterior hairline, mental retardation, short stature, and other malformations. Chromosomal analysis for her mother showed a normal karyotype. Her father and younger brother were phenotypically normal.

Result

Phenotypical features were quite similar throughout other cases and in accordance with the usual phenotype of del(18p) suggested within the same cases and among the del(18p) cases described. She underwent blepharoplasty, which improved her appearance.

Conclusion

18p deletion syndrome is diagnosed by gene analysis. Plastic surgeries for improving the appearance might be an option for these patients.

18p Deletion Syndrome: Case Report with Clinical Consideration and Management

18p deletion syndrome is characterized by the deletion of short arm of chromosome 18. Presentation of this syndrome is quite variable with dysmorphic features, growth deficiencies, and mental retardation with poor verbal performance. Few patients even fail to thrive when malformations involving the heart and brain are severe. In the present article, we report an isolated case of 18p deletion in a 23-year-old female who for the first time reported to the hospital for dental problems. The patient was short statured with mental retardation and craniofacial, skeletal, dental, and endocrinal abnormalities. Such presentation warrants prompt diagnosis for effective management. Furthermore, genetic counseling for such patients and their families should be considered as a part of treatment itself.

Anterior Pituitary Aplasia in an Infant with Ring Chromosome 18p Deletion

We present the first reported case of an infant with 18p deletion syndrome with anterior pituitary aplasia secondary to a ring chromosome. Endocrine workup soon after birth was reassuring; however, repeat testing months later confirmed central hypopituitarism. While MRI reading initially indicated no midline defects, subsequent review of the images confirmed anterior pituitary aplasia with ectopic posterior pituitary. This case demonstrates how deletion of genetic material, even if resulting in a chromosomal ring, still results in a severe syndromic phenotype. Furthermore, it demonstrates the necessity of close follow-up in the first year of life for children with 18p deletion syndrome and emphasizes the need to verify radiology impressions if there is any doubt as to the radiologic findings.

Array-based molecular karyotyping in fetuses with isolated brain malformations identifies disease-causing CNVs

Background

The overall birth prevalence for congenital malformations of the central nervous system (CNS) among Europeans may be as high as 1 in 100 live births. The etiological factors remain largely unknown. The aim of this study was to detect causative copy number variations (CNVs) in fetuses of terminated pregnancies with prenatally detected isolated brain malformations.

Methods

Array-based molecular karyotyping was performed in a cohort of 35 terminated fetuses with isolated CNS malformations. Identified putative disease-causing CNVs were confirmed using quantitative polymerase chain reaction or multiplex ligation-dependent probe amplification.

Results

Based on their de novo occurrence and/or their established association with congenital brain malformations, we detected five disease-causing CNVs in four fetuses involving chromosomal regions 6p25.1-6p25.3 (FOXC1), 6q27, 16p12.3, Xp22.2-Xp22.32 (MID1), and Xp22.32-Xp22.33. Furthermore, we detected a probably disease-causing CNV involving chromosomal region 3p26.3 in one fetus, and in addition, we detected 12 CNVs in nine fetuses of unknown clinical significance. All CNVs except for two were absent in 1307 healthy in-house controls (frequency <0.0008). Each of the two CNVs present in in-house controls was present only once (frequency = 0.0008). Furthermore, our data suggests the involvement of CNTN6 and KLHL15 in the etiology of agenesis of the corpus callosum, the involvement of RASD1 and PTPRD in Dandy-Walker malformation, and the involvement of ERMARD in ventriculomegaly.

Conclusions

Our study suggests that CNVs play an important role in the etiology of isolated brain malformations.

Prenatal diagnosis of holoprosencephaly with proboscis and cyclopia caused by monosomy 18p resulting from unbalanced whole-arm translocation of 18;21

A case of holoprosencephaly (HPE) with proboscis, fused eyes in one orbit, and cyclopia was diagnosed by fetal ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI). Ultrasonographic examination at 28 weeks of gestation showed fusion of the frontal part of the brain and ventricular dilation. Subsequent CT and MRI examinations confirmed this anomaly as alobar HPE. Amniocentesis followed by chromosome analysis demonstrated karyotype as de novo 45,XY, der (18;21)(q10;q10), with deletion of a short arm of chromosome 18. The pregnancy ended in a premature delivery of a male neonate weighing 1716 g at 34 weeks. Macroscopically, there were mid-frontal proboscis and single orbit with two eyes without normal nasal structures. He died 1 h after birth.

A review of 18p deletions

Since 18p- was first described in 1963, much progress has been made in our understanding of this classic deletion condition. We have been able to establish a fairly complete picture of the phenotype when the deletion breakpoint occurs at the centromere, and we are working to establish the phenotypic effects when each gene on 18p is hemizygous. Our aim is to provide genotype-specific anticipatory guidance and recommendations to families with an 18p- diagnosis. In addition, establishing the molecular underpinnings of the condition will potentially suggest targets for molecular treatments. Thus, the next step is to establish the precise effects of specific gene deletions. As we look forward to deepening our understanding of 18p-, our focus will continue to be on the establishment of robust genotype-phenotype correlations and the penetrance of these phenotypes. We will continue to follow our 18p- cohort closely as they age to determine the presence or absence of some of these diagnoses, including spinocerebellar ataxia (SCA), facioscapulohumeral muscular dystrophy (FSHD), and dystonia. We will also continue to refine the critical regions for other phenotypes as we enroll additional (hopefully informative) participants into the research study and as the mechanisms of the genes in these regions are elucidated. Mouse models will also be developed to further our understanding of the effects of hemizygosity as well as to serve as models for treatment development.

Hemizygosity for SMCHD1 in Facioscapulohumeral Muscular Dystrophy Type 2: Consequences for 18p Deletion Syndrome

Facioscapulohumeral muscular dystrophy (FSHD) is most often associated with variegated expression in somatic cells of the normally repressed DUX4 gene within the D4Z4-repeat array. The most common form, FSHD1, is caused by a D4Z4-repeat array contraction to a size of 1-10 units (normal range 10-100 units). The less common form, FSHD2, is characterized by D4Z4 CpG hypomethylation and is most often caused by loss-of-function mutations in the structural maintenance of chromosomes hinge domain 1 (SMCHD1) gene on chromosome 18p. The chromatin modifier SMCHD1 is necessary to maintain a repressed D4Z4 chromatin state. Here, we describe two FSHD2 families with a 1.2-Mb deletion encompassing the SMCHD1 gene. Numerical aberrations of chromosome 18 are relatively common and the majority of 18p deletion syndrome (18p-) cases have, such as these FSHD2 families, only one copy of SMCHD1. Our finding therefore raises the possibility that 18p- cases are at risk of developing FSHD. To address this possibility, we combined genome-wide array analysis data with D4Z4 CpG methylation and repeat array sizes in individuals with 18p- and conclude that approximately 1:8 18p- cases might be at risk of developing FSHD.

Whole arm deletions of 18p: medical and developmental effects

Deletions of the short arm of chromosome 18 have been well-described in case reports. However, the utility of these descriptions in clinical practice is limited by varied and imprecise breakpoints. As we work to establish genotype-phenotype correlations for 18p-, it is critical to have accurate and complete clinical descriptions of individuals with differing breakpoints. In addition, the developmental profile of 18p- has not been well-delineated. We undertook a thorough review of the medical histories of 31 individuals with 18p- and a breakpoint in the centromeric region. We collected developmental data using mailed surveys and questionnaires. The most common findings included neonatal complications; cardiac anomalies; hypotonia; MRI abnormalities; endocrine dysfunction; strabismus; ptosis; and refractive errors. Less common features included holoprosencephaly and its microforms; hearing loss; and orthopedic anomalies. The developmental effects of the deletion appear to be less severe than reported in the literature, as average IQ scores were in the range of borderline intellectual functioning. Based on responses to standardized questionnaires, it appears this population has marked difficulty with activities of daily living, though several young adults were able to live independent of their parents. This manuscript represents the most comprehensive description of a cohort of 18p- individuals with identical breakpoints. Despite identical breakpoints, a great deal of phenotype variability remained among this population, suggesting that many of the genes on 18p- cause low-penetrance phenotypes when present in a hemizygous state. Future efforts will focus on the clinical description of individuals with more distal breakpoints and the identification of critical regions and candidate genes.

A non-syndromic intellectual disability associated with a de novo microdeletion at 7q and 18p, microduplication at Xp, and 18q partial trisomy detected using chromosomal microarray analysis approach

BACKGROUND

Chromosome abnormalities that segregate with a disease phenotype can facilitate the identification of disease loci and genes. The relationship between chromosome 18 anomalies with severe intellectual disability has attracted the attention of cytogeneticists worldwide. Duplications of the X chromosome can cause intellectual disability in females with variable phenotypic effects, due in part to variations in X-inactivation patterns. Additionally, deletions of the 7qter region are associated with a range of phenotypes.

RESULTS

We report the first case of de novo microdeletion at 7q and 18p, 18q partial trisomy, microduplication at Xp associated to intellectual disability in a Brazilian child, presenting a normal karyotype. Karyotyping showed any chromosome alteration. Chromosomal microarray analysis detected a de novo microdeletion at 18p11.32 and 18q partial trisomy, an inherited microdeletion at 7q31.1 and a de novo microduplication at Xp22.33p21.3.

CONCLUSIONS

Our report illustrates a case that presents complex genomic imbalances which may contribute to a severe clinical phenotypes. The rare and complex phenotypes have to be investigated to define the subsets and allow the phenotypes classification.