The 6p25 deletion syndrome: An update on a rare neurocristopathy

Structural Variant Disrupting the Expression of the Remote FOXC1 Gene in a Patient with Syndromic Complex Microphthalmia

Ocular malformations (OMs) arise from early defects during embryonic eye development. Despite the identification of over 100 genes linked to this heterogeneous group of disorders, the genetic cause remains unknown for half of the individuals following Whole-Exome Sequencing. Diagnosis procedures are further hampered by the difficulty of studying samples from clinically relevant tissue, which is one of the main obstacles in OMs. Whole-Genome Sequencing (WGS) to screen for non-coding regions and structural variants may unveil new diagnoses for OM individuals. In this study, we report a patient exhibiting a syndromic OM with a de novo 3.15 Mb inversion in the 6p25 region identified by WGS. This balanced structural variant was located 100 kb away from the FOXC1 gene, previously associated with ocular defects in the literature. We hypothesized that the inversion disrupts the topologically associating domain of FOXC1 and impairs the expression of the gene. Using a new type of samples to study transcripts, we were able to show that the patient presented monoallelic expression of FOXC1 in conjunctival cells, consistent with the abolition of the expression of the inverted allele. This report underscores the importance of investigating structural variants, even in non-coding regions, in individuals affected by ocular malformations.

Case report: Extending the spectrum of clinical and molecular findings in FOXC1 haploinsufficiency syndrome

FOXC1 is a ubiquitously expressed forkhead transcription factor that plays a critical role during early development. Germline pathogenic variants in FOXC1 are associated with anterior segment dysgenesis and Axenfeld-Rieger syndrome (ARS, #602482), an autosomal dominant condition with ophthalmologic anterior segment abnormalities, high risk for glaucoma and extraocular findings including distinctive facial features, as well as dental, skeletal, audiologic, and cardiac anomalies. De Hauwere syndrome is an ultrarare condition previously associated with 6p microdeletions and characterized by anterior segment dysgenesis, joint instability, short stature, hydrocephalus, and skeletal abnormalities. Here, we report clinical findings of two unrelated adult females with FOXC1 haploinsufficiency who have ARS and skeletal abnormalities. Final molecular diagnoses of both patients were achieved using genome sequencing. Patient 1 had a complex rearrangement involving a 4.9 kB deletion including FOXC1 coding region (Hg19; chr6:1,609,721-1,614,709), as well as a 7 MB inversion (Hg19; chr6:1,614,710-8,676,899) and a second deletion of 7.1 kb (Hg19; chr6:8,676,900-8,684,071). Patient 2 had a heterozygous single nucleotide deletion, resulting in a frameshift and a premature stop codon in FOXC1 (NM_001453.3): c.467del, p.(Pro156Argfs*25). Both individuals had moderate short stature, skeletal abnormalities, anterior segment dysgenesis, glaucoma, joint laxity, pes planovalgus, dental anomalies, hydrocephalus, distinctive facial features, and normal intelligence. Skeletal surveys revealed dolichospondyly, epiphyseal hypoplasia of femoral and humeral heads, dolichocephaly with frontal bossin gand gracile long bones. We conclude that haploinsufficiency of FOXC1 causes ARS and a broad spectrum of symptoms with variable expressivity that at its most severe end also includes a phenotype overlapping with De Hauwere syndrome.

Axenfeld-Rieger syndrome: more than meets the eye

BACKGROUND

Axenfeld-Rieger syndrome (ARS) is characterised by typical anterior segment anomalies, with or without systemic features. The discovery of causative genes identified ARS subtypes with distinct phenotypes, but our understanding is incomplete, complicated by the rarity of the condition.

METHODS

Genetic and phenotypic characterisation of the largest reported ARS cohort through comprehensive genetic and clinical data analyses.

RESULTS

128 individuals with causative variants in PITX2 or FOXC1, including 81 new cases, were investigated. Ocular anomalies showed significant overlap but with broader variability and earlier onset of glaucoma for FOXC1-related ARS. Systemic anomalies were seen in all individuals with PITX2-related ARS and the majority of those with FOXC1-related ARS. PITX2-related ARS demonstrated typical umbilical anomalies and dental microdontia/hypodontia/oligodontia, along with a novel high rate of Meckel diverticulum. FOXC1-related ARS exhibited characteristic hearing loss and congenital heart defects as well as previously unrecognised phenotypes of dental enamel hypoplasia and/or crowding, a range of skeletal and joint anomalies, hypotonia/early delay and feeding disorders with structural oesophageal anomalies in some. Brain imaging revealed highly penetrant white matter hyperintensities, colpocephaly/ventriculomegaly and frequent arachnoid cysts. The expanded phenotype of FOXC1-related ARS identified here was found to fully overlap features of De Hauwere syndrome. The results were used to generate gene-specific management plans for the two types of ARS.

CONCLUSION

Since clinical features of ARS vary significantly based on the affected gene, it is critical that families are provided with a gene-specific diagnosis, PITX2-related ARS or FOXC1-related ARS. De Hauwere syndrome is proposed to be a FOXC1opathy.

The phenotypic spectrum of terminal and subterminal 6p deletions based on a social media-derived cohort and literature review

BACKGROUND

Terminal 6p deletions are rare, and information on their clinical consequences is scarce, which impedes optimal management and follow-up by clinicians. The parent-driven Chromosome 6 Project collaborates with families of affected children worldwide to better understand the clinical effects of chromosome 6 aberrations and to support clinical guidance. A microarray report is required for participation, and detailed phenotype information is collected directly from parents through a multilingual web-based questionnaire. Information collected from parents is then combined with case data from literature reports. Here, we present our findings on 13 newly identified patients and 46 literature cases with genotypically well-characterised terminal and subterminal 6p deletions. We provide phenotype descriptions for both the whole group and for subgroups based on deletion size and HI gene content.

RESULTS

The total group shared a common phenotype characterised by ocular anterior segment dysgenesis, vision problems, brain malformations, congenital defects of the cardiac septa and valves, mild to moderate hearing impairment, eye movement abnormalities, hypotonia, mild developmental delay and dysmorphic features. These characteristics were observed in all subgroups where FOXC1 was included in the deletion, confirming a dominant role for this gene. Additional characteristics were seen in individuals with terminal deletions exceeding 4.02 Mb, namely complex heart defects, corpus callosum abnormalities, kidney abnormalities and orofacial clefting. Some of these additional features may be related to the loss of other genes in the terminal 6p region, such as RREB1 for the cardiac phenotypes and TUBB2A and TUBB2B for the cerebral phenotypes. In the newly identified patients, we observed previously unreported features including gastrointestinal problems, neurological abnormalities, balance problems and sleep disturbances.

CONCLUSIONS

We present an overview of the phenotypic characteristics observed in terminal and subterminal 6p deletions. This reveals a common phenotype that can be highly attributable to haploinsufficiency of FOXC1, with a possible additional effect of other genes in the 6p25 region. We also delineate the developmental abilities of affected individuals and report on previously unrecognised features, showing the added benefit of collecting information directly from parents. Based on our overview, we provide recommendations for clinical surveillance to support clinicians, patients and families.

Chromosome 6p25 deletion syndrome: A case report and review of ophthalmic features

The 6p25 deletion syndrome is a rare genetic disorder characterized by a wide spectrum of congenital anomalies. Ophthalmic abnormalities appear to be highly associated with the syndrome, although this relationship has not been well characterized to date. We conducted a systematic literature review to highlight the ocular features in patients with this deletion syndrome and describe a 7-month-old female who has a 6.07 MB 6p25.1p25.3 deletion and a 4.25 MB 17q25.3 duplication. Our patient presented with multiple congenital anomalies, including macrocephaly, frontal bossing, low set ears, tent-shaped mouth, saddle nose, flat midface, and hearing impairment. Her ophthalmic features included proptosis, down-slanting palpebral fissures, hypertelorism, nystagmus, bilateral posterior embryotoxon, and decentered and abnormally shaped pupils. A systematic review of the published cases with sufficient clinical eye descriptions included 63 cases with a confirmed 6p25 deletion. The most common eye findings observed were posterior embryotoxon, iris hypoplasia, corectopia, cornea opacity, and glaucoma.

The clinical and genetic findings in a Chinese family with Axenfeld-Rieger syndrome

Objecive

To describe the clinical and genetic findings of an Axenfeld-Rieger syndrome (ARS) family with a new PITX2 splicing mutation.

Methods

A Chinese ARS family with five affected individuals was recruited. Exome sequencing was performed on the proband and the variant (C.253-9C > A) in PITX2 gene was detected as a pathogenic mutation. Sanger sequencing was performed for verification and cosegregation analysis. Real-time polymerase chain reaction (RT- PCR) and Western blotting were performed to verify the expression of the pathogenic gene.

Results

All the patients showed abnormalities in the anterior segment of both eyes including posterior embryotoxon, corectopia, iris dysplasia, and iridocorneal tissue adhesions. In addition, they all presented systemic features, including maxillary hypoplasia, underbite, hypodontia, conical teeth. Only III-7 showed obvious umbilical skin. In the PITX2 family, we identified a novel heterozygous splicing mutation (C.253-9C > A) which was confirmed by Sanger sequencing to be completely cosegregated with the ARS phenotype. Real-time quantitative PCR and Western results showed that PITX2 mRNA and protein expression were significantly lower in patients compared with unrelated normal controls.

Conclusion

In the ARS pedigree, we summarized the variable phenotype, described a novel PITX2 splicing mutation which expand the genetic spectrum of ARS. We further confirmed the possibility of development of ARS induced by this PITX2 gene deficiency.

Cytogenetic and molecular analysis of distal 4q duplication with distinctive phenotype using single-nucleotide polymorphism array

Aims

There is little knowledge about partial trisomy 4q and the genotype–phenotype correlation. In this study, we presented the detail of two Chinese families with partial distal 4q duplication in an attempt to clarify the correlation between the genotype and the phenotype.

Methods

Two pedigrees with distal 4q duplication were enrolled in this study. Karyotype analysis and single-nucleotide polymorphism (SNP) array detection were performed for prenatal diagnosis. Fluorescence in situ hybridization analysis. (FISH) was conducted to verify the copy number variants.

Results

Two families with partial trisomy 4q were identified. The fetus in pedigree 1 exhibited multiple ultrasound anomalies including intrauterine growth restriction and an atrioventricular septal defect who had a duplication of 4q28.3-qter associate with 6p25.2-p25.3 deletion, which resulted from balanced translocation carried by his father t(4;6)(q28.3;p25.2). The fetus in pedigree 2 had a distal 4q28.3-qter duplication combined with monosomy of Xp21.3-p22.3, and the karyotype was described as 46,X,der(X)t(X;4)(p21.3;q28.3)mat, which originally inherited from the pregnant woman who exhibited a mild clinical phenotype limited to short stature.

Conclusions

In our study, we for the first time identified the partial trisomy 4q associate with 6p or Xp deletion. In addition, our finding further strengthens that mild clinical phenotype in 4q duplication case may be due to the spreading of X inactivation to the autosomal in derivation of chromosome X.

Disruption of foxc1 genes in zebrafish results in dosage-dependent phenotypes overlapping Axenfeld-Rieger syndrome

The Forkhead Box C1 (FOXC1) gene encodes a forkhead/winged helix transcription factor involved in embryonic development. Mutations in this gene cause dysgenesis of the anterior segment of the eye, most commonly Axenfeld-Rieger syndrome (ARS), often with other systemic features. The developmental mechanisms and pathways regulated by FOXC1 remain largely unknown. There are two conserved orthologs of FOXC1 in zebrafish, foxc1a and foxc1b. To further examine the role of FOXC1 in vertebrates, we generated foxc1a and foxc1b single knockout zebrafish lines and bred them to obtain various allelic combinations. Three genotypes demonstrated visible phenotypes: foxc1a-/- single homozygous and foxc1-/- double knockout homozygous embryos presented with similar characteristics comprised of severe global vascular defects and early lethality, as well as microphthalmia, periocular edema and absence of the anterior chamber of the eye; additionally, fish with heterozygous loss of foxc1a combined with homozygosity for foxc1b (foxc1a+/-;foxc1b-/-) demonstrated craniofacial defects, heart anomalies and scoliosis. All other single and combined genotypes appeared normal. Analysis of foxc1 expression detected a significant increase in foxc1a levels in homozygous and heterozygous mutant eyes, suggesting a mechanism for foxc1a upregulation when its function is compromised; interestingly, the expression of another ARS-associated gene, pitx2, was responsive to the estimated level of wild-type Foxc1a, indicating a possible role for this protein in the regulation of pitx2 expression. Altogether, our results support a conserved role for foxc1 in the formation of many organs, consistent with the features observed in human patients, and highlight the importance of correct FOXC1/foxc1 dosage for vertebrate development.

Haploinsufficiency of RREB1 causes a Noonan-like RASopathy via epigenetic reprogramming of RAS-MAPK pathway genes

RAS-MAPK signaling mediates processes critical to normal development including cell proliferation, survival, and differentiation. Germline mutation of RAS-MAPK genes lead to the Noonan-spectrum of syndromes. Here, we present a patient affected by a 6p-interstitial microdeletion with unknown underlying molecular etiology. Examination of 6p-interstitial microdeletion cases reveals shared clinical features consistent with Noonan-spectrum disorders including short stature, facial dysmorphia and cardiovascular abnormalities. We find the RAS-responsive element binding protein-1 (RREB1) is the common deleted gene in multiple 6p-interstitial microdeletion cases. Rreb1 hemizygous mice display orbital hypertelorism and cardiac hypertrophy phenocopying the human syndrome. Rreb1 haploinsufficiency leads to sensitization of MAPK signaling. Rreb1 recruits Sin3a and Kdm1a to control H3K4 methylation at MAPK pathway gene promoters. Haploinsufficiency of SIN3A and mutations in KDM1A cause syndromes similar to RREB1 haploinsufficiency suggesting genetic perturbation of the RREB1-SIN3A-KDM1A complex represents a new category of RASopathy-like syndromes arising through epigenetic reprogramming of MAPK pathway genes.

Clinical application of chromosomal microarray analysis for fetuses with craniofacial malformations

Background

The potential correlations between chromosomal abnormalities and craniofacial malformations (CFMs) remain a challenge in prenatal diagnosis. This study aimed to evaluate 118 fetuses with CFMs by applying chromosomal microarray analysis (CMA) and G-banded chromosome analysis.

Results

Of the 118 cases in this study, 39.8% were isolated CFMs (47/118) whereas 60.2% were non-isolated CFMs (71/118). The detection rate of chromosomal abnormalities in non-isolated CFM fetuses was significantly higher than that in isolated CFM fetuses (26/71 vs. 7/47, p = 0.01). Compared to the 16 fetuses (16/104; 15.4%) with pathogenic chromosomal abnormalities detected by karyotype analysis, CMA identified a total of 33 fetuses (33/118; 28.0%) with clinically significant findings. These 33 fetuses included cases with aneuploidy abnormalities (14/118; 11.9%), microdeletion/microduplication syndromes (9/118; 7.6%), and other pathogenic copy number variations (CNVs) only (10/118; 8.5%).We further explored the CNV/phenotype correlation and found a series of clear or suspected dosage-sensitive CFM genes including TBX1, MAPK1, PCYT1A, DLG1, LHX1, SHH, SF3B4, FOXC1, ZIC2, CREBBP, SNRPB, and CSNK2A1.

Conclusion

These findings enrich our understanding of the potential causative CNVs and genes in CFMs. Identification of the genetic basis of CFMs contributes to our understanding of their pathogenesis and allows detailed genetic counselling.

Sensorineural hearing loss and hypoplastic cochlea in Axenfeld-Rieger syndrome with FOXC1 mutation

OBJECTIVE

Axenfeld-Rieger syndrome (ARS) type 3 is a rare autosomal dominant disease, characterized by anterior segment dysgenesis of the eye, hearing loss, and cardiac defects. ARS type 3 is highly associated with FOXC1 mutations, which induces developmental disorders of neural crest cells. Most studies about ARS patients focused on ophthalmologic findings, but details in their hearing loss have not yet been revealed. In this report, we investigated audiological and otological manifestations in the ARS type 3 patient who had the novel heterozygous FOXC1 mutation leading deletion at the forkhead DNA-binding domain.

METHODS AND RESULTS

Pure tone audiometry showed bilateral sensorineural hearing loss (SNHL) and audiological examinations confirmed that major dysfunctions existed in the cochlea, rather than the spiral ganglion neurons and the cochlear nerve. CT and MRI revealed the hypoplastic cochlea at both sides. Given that the 6p25 deletion syndrome, lacking one allele of the FOXC1 gene, shows similar, but more severe cochlear malformations than the present case, the FOXC1 mutations might contribute to the hypoplasia and dysfunctions in the cochlea.

CONCLUSION

To our knowledge, this is the first report demonstrating that the ARS type 3 patient with the FOXC1 mutation has the hypoplasia and dysfunctions in the cochlea, which results in bilateral SNHL.

Detection of submicroscopic chromosomal aberrations by chromosomal microarray analysis for the prenatal diagnosis of central nervous system abnormalities

Background

Central nervous system (CNS) abnormalities are a group of serious birth defects associated with high rates of stillbirths, infant death, or abnormal development, and various disease‐causing copy number variations play a much more important role in the etiology of CNS abnormalities. This study intends to present a retrospective study of the prenatal diagnosis and the pregnancy outcome of fetuses diagnosed with CNS abnormalities, and evaluate the clinical value of chromosomal microarray analysis (CMA) in prenatal diagnosis of CNS abnormalities.

Methods

A total of 356 fetuses with CNS abnormalities with or without other ultrasound abnormalities subjected to invasive prenatal diagnosis at the first affiliated hospital of Air Force Medical University from January 2015 to August 2018. All cases have performed both karyotyping and CMA concurrently, but 20 fetuses with chromosome aneuploidy were excluded in the current study.

Results

The CMA identified pathogenic copy number variants (pCNVs) in 27/336 (8.03%) fetuses, likely pCNVs in 8/336 (2.38%) fetuses, and variants of unknown significance (VOUS) in 11/336 (3.27%) fetuses. A total of 222 cases had single CNS abnormalities and the pCNVs detection rate was 5.86% (13/222), the remaining 114 cases including CNS abnormalities plus other structural abnormalities, ultrasonographic soft markers and two or more CNS abnormalities, the pCNVs detection rate was 12.3% (14/114).

Conclusions

Fetuses with CNS abnormalities have a higher risk of chromosomal abnormalities, our study showed that CNVs play an important role in the etiology of CNS abnormalities. The application of CMA could increase the detection rate of pCNVs causing CNS abnormalities.

Exome Sequencing in a Swiss Childhood Glaucoma Cohort Reveals CYP1B1 and FOXC1 Variants as Most Frequent Causes

Purpose

The aim of this study was to investigate the molecular basis of childhood glaucoma in Switzerland to recommend future targeted genetic analysis in the Swiss population.

Methods

Whole-exome sequencing and copy number variation (CNV) analysis was performed in a Swiss cohort of 18 patients from 14 unrelated families. Identified variants were validated by Sanger sequencing and multiplex ligation-dependent probe amplification. Breakpoints of structural variants were determined by a microarray. A minigene assay was conducted for functional analysis of a splice site variant.

Results

A diagnosis of primary congenital glaucoma was made in 14 patients, of which six (43%) harbored pathogenic variants in CYP1B1, one (7%) a frameshift variant in FOXC1, and seven (50%) remained without a genetic diagnosis. Three patients were diagnosed with glaucoma associated with nonacquired ocular anomalies, of which two patients with mild ocular features of Axenfeld-Rieger syndrome harbored a FOXC1 duplication plus an additional FOXC1 missense variant, and one patient with a Barkan membrane remained without genetic diagnosis. A diagnosis of juvenile open-angle glaucoma was made in one patient, and genetic analysis revealed a FOXC1 duplication.

Conclusions

Sequencing of CYP1B1 and FOXC1, as well as analysis of CNVs in FOXC1, should be performed before extended gene panel sequencing.

Translational Relevance

The identification of the molecular cause of childhood glaucoma is a prerequisite for genetic counseling and personalized care for patients and families.

Novel Phenotype of 6p25 Deletion Syndrome Presenting Juvenile Parkinsonism and Brain Calcification

BACKGROUND

Chromosome 6p25 deletion syndrome is a rare neurocristopathy with variable clinical features. The objective of the current study was to describe a novel phenotype for autosomal-dominant chromosome 6p25 deletion syndrome. The presentation included bilateral basal ganglia and subcortical calcifications and juvenile parkinsonism, resembling primary familial brain calcification.

METHODS

Phenotypic characterization, exome sequencing, and oligonucleotide array were carried out in the index family.

RESULTS

The index patient and her mother had a history of developmental delay, mild facial dysmorphism, Axenfield eye anomalies, slight intellectual disability, and subsequently developed levodopa-responsive parkinsonism in early adulthood. Brain-computed tomography showed bilateral basal ganglia and subcortical calcifications. Magnetic resonance imaging revealed diffuse white matter lesions. A ^99mTc TRODAT single-photon emission computed tomography scan revealed bilateral dopaminergic denervation. Whole-exome sequencing and oligonucleotide array-based comparative genomic hybridization revealed a 2.27-Mb chromosome 6pter-p24 deletion, which cosegregated within the family.

CONCLUSIONS

Our findings extended the current phenotypic spectrum of chromosome 6p25 deletion syndrome. © 2020 International Parkinson and Movement Disorder Society.

Ring chromosome 6 in a child with anterior segment dysgenesis and review of its overlap with other FOXC1 deletion phenotypes

Here, we report a patient with ring chromosome 6 [r(6)], associated with anterior segment dysgenesis (ASD) and other anomalies. The phenotype was due to a 1880 kb microdeletion at 6p25.3 identified by whole-genome array analysis, and was mainly attributable to a FOXC1 haploinsufficiency. Currently 37 patients with r(6) have been reported. We found that facial dysmorphism, ASD, heart anomalies, brain anomalies, and hearing loss are constant features only in severe cases of r(6), mainly related to hemizygosity of FOXC1. Thus, overlaps with other FOXC1 related phenotypes, such as the 6p25 deletion syndrome, Axenfeld-Rieger syndrome type 3, and ASD type 3. Contrarily, those patients whose r(6) does not disrupt FOXC1, have mild or moderate phenotypes and do not exhibit ASD.

Cerebral White Matter Lesions and Dysmorphisms: Signs Suggestive of 6p25 Deletion Syndrome-Literature Review

Deletion of the region including chromosome 6p25 has been defined as a syndrome, with more than 68 reported cases. Individuals affected by the syndrome exhibit variable findings, including developmental delay and intellectual disability, cardiac anomalies, dysmorphic features, and-less commonly-skeletal and renal malformations. Ocular and hearing abnormalities are the most notable presenting features. The region encompasses more than 15 genes, of which the FOX group is the most likely causal factor of the clinical manifestations. We report the case of a 2-year-old child with developmental delay, generalized hypotonia, facial dysmorphism, and anomalies involving malformations of the eyes, heart, teeth, and skeleton. The magnetic resonance imaging (MRI) of the child's brain displayed cerebral anomalies involving the white matter, perivascular spaces, and corpus callosum. Array-CGH (comparative genomic hybridization) analysis displayed a de novo partial deletion of the short arm of chromosome 6, extending 5.13 Mb from nt 407.231 to nt 5.541.179. In infancy, neuroradiologic findings of abnormalities in the cerebral white matter and other neurologic anomalies elsewhere in the brain, in association with dysmorphisms and malformations, are highly suggestive of the diagnosis of 6p25 deletion syndrome. When these anomalies are found, the syndrome must be included in the differential diagnosis of disorders affecting the cerebral white matter.

Cytogenetic and genetic investigation of miscarriage cases in Eastern China

Objective: Recurrent miscarriage (RM) affects about 5% of pregnancies. Etiology of 30-50% RM cases remains unknown. Advanced highly sensitive detection and analysis methods may help solve some of the cases.Methods: Products of conception from 1155 RM cases were analyzed using classic karyotyping. Some cases without abnormal findings were subjected to next generation DNA sequencing (NGS) and chromosome copy number variation (CNV) analysis.Results: Classic karyotyping identified abnormalities in 56.62% of the cases. Of the103 specimens analyzed using NGS, 39 (37.86%) were found to carry "pathogenic" CNVs. Recurrent microdeletions and microduplications were identified, and some with unique distribution patterns.Conclusion: NGS CNV analysis is a highly sensitive and flexible method for detecting genetic abnormalities in RM cases.

Deletion of 6p25.3 Is Associated with Cerebrovascular Dolichoectasia: Report of 2 Cases

Developmental dolichoectasia of the intracranial vessels is a rare occurrence. The authors report 2 sibling pediatric patients who were born with 6p25.3 deletion, associated with carotid and vertebrobasilar dolichoectasia. MRI imaging of both children showed asymptomatic elongation and dilation of the vertebrobasilar system and "kissing" carotid arteries. A microarray analysis was also performed for both patients, which identified a 1.5-Mb deletion of 6p25.3 covering 15 genes including FOXC1, which has been implicated in defects in vascular morphogenesis.

A novel unbalanced translocation between the short arms of chromosomes 6 and 16 in a newborn girl: Clinical features and management

The reporting of previously undescribed genetic mutations and resulting clinical phenotypes guides management and enables a more accurate prognosis for clinicians treating newborns with similar features. Previous cases of 6p deletions and 16p duplications have been described as separate entities. This patient presents with both and has a unique phenotype.