Phenotypic expansion of the supernumerary derivative (22) chromosome syndrome: VACTERL and Hirschsprung's disease

Cat eye syndrome caused by 22q11.1q11.21 duplication: case report in a Chinese family

PURPOSE

 This paper presents a report on two uncommon instances of cat eye syndrome in a Chinese family.

CASE PRESENTATION

The proband, a 23-year-old female, exhibited a diminutive cornea and complete blindness in her right eye, and the uncorrected distance visual acuity of her left eye was 0.7 LogMAR. Peripheral blood chromosome karyotyping reveal a karyotype of 47, XX, + mar. Subsequent analysis of chromosome copy number variation unveiled a 1.5 Mb duplication in the 22q11.1q11.21 region of the proband. The proband's mother,aged 49, displayed small eyes, wide-set eyes, downward slanting eyelids, and congenital heart disease. Chromosome copy number variation analysis also showed a 1.55 Mb duplication in the 22q11.1q11.21 region of chromosome 22 in the proband's mother. Ultimately, both members of this family were diagnosed with cat eye syndrome.

CONCLUSION

 Cat eye syndrome is a rare genetic disorder that greatly affects patients' lives and requires personalized treatment. This study provides new evidence for a better understanding of the diagnosis of cat eye syndrome and emphasizes the importance of genetic counseling and supervision.

DiGeorge syndrome chromosome region deletion and duplication: Prenatal genotype-phenotype variability in fetal ultrasound and MRI

OBJECTIVE

The aim of the study was to assess genotype-phenotype correlation of prenatally diagnosed fetal DGS and dup22q11 syndrome by fetal molecular genetic analysis, fetal ultrasound, and/or MRI.

METHODS

In this retrospective consecutive case series, pregnant women were screened for fetal anomalies during a period of 10 years. Fetal genotype was assessed in 72 cases upon the occurrence of five prenatal fetal phenotypic features: cardiac anomalies, hypo/aplastic thymus, craniofacial malformations, urinary abnormalities, or IUGR; genotype-phenotype correlation was tested to potentially improve prenatal diagnosis of fetal DGS and dup22q11 syndrome.

RESULTS

Fetal genotypes of deletions or duplications in proximal clusters of LCR22s (A-B) were associated with fetal cardiac anomalies in combination with hypo/aplastic thymus and craniofacial malformations, suggesting a correlation with deleted HIRA. TOF associated with aplastic thymus in combination with renal defects indicated a relevant correlation with TBX1 deletion. Deletions in central LCR22s (B-D) with the loss of CRKL supposed a trend of genotype-phenotype correlation with fetal urinary abnormalities.

CONCLUSION

Genotype-phenotype correlation might improve prenatal diagnosis of fetal DGS and dup22q11 syndrome. Hence, prenatal screening and counseling is highly enhanced by a combination of fetal molecular genetic analysis, fetal ultrasound, and/or MRI. The implications of these findings remain to be explored.

Phenotypic diversity of patients diagnosed with VACTERL association

The combination of vertebral, anal, cardiac, tracheo-esophageal, renal and limb anomalies termed VACTERL association, also referred to as VATER, has been used as a clinical descriptor and more recently, a diagnosis of exclusion, for a specific group of phenotypic manifestations that have been observed to co-occur non-randomly. Though the causes remain elusive and poorly understood in most patients, VACTERL association is thought to be due to defects in early embryogenesis and is likely genetically heterogeneous. We present data on 36 patients diagnosed with VACTERL association in addition to describing the phenotypic diversity of each component feature. Unique cases in our cohort include a patient with a 498.59 kb microdeletion in the 16p11.2 region and another with a 215 kb duplication in the 3p25.2 region. Our findings expand upon the current understanding of VACTERL association and guide future research aimed at determining its etiology.

Underlying genetic factors of the VATER/VACTERL association with special emphasis on the "Renal" phenotype

The acronym VATER/VACTERL association (OMIM #192350) refers to the rare non-random co-occurrence of the following component features (CFs): vertebral defects (V), anorectal malformations (A), cardiac defects (C), tracheoesophageal fistula with or without esophageal atresia (TE), renal malformations (R), and limb defects (L). According to epidemiological studies, the majority of patients with VATER/VACTERL association present with a "Renal" phenotype comprising a large spectrum of congenital renal anomalies. This finding is supported by evidence linking all of the human disease genes for the VATER/VACTERL association identified to date, namely, FGF8, FOXF1, HOXD13, LPP, TRAP1, and ZIC3, with renal malformations. Here we review these genotype-phenotype correlations and suggest that the elucidation of the genetic causes of the VATER/VACTERL association will ultimately provide insights into the genetic causes of the complete spectrum of congenital renal anomalies per se.

Role of Genetic Factors in the Pathogenesis of Radial Deficiencies in Humans

Radial deficiencies (RDs), defined as under/abnormal development or absence of any of the structures of the forearm, radial carpal bones and thumb, occur with a live birth incidence ranging from 1 out of 30,000 to 1 out 6,000 newborns and represent about one third/one fourth of all the congenital upper limb anomalies. About half of radial disorders have a mendelian cause and pattern of inheritance, whereas the remaining half appears sporadic with no known gene involved. In sporadic forms certain anomalies, such as thumb or radial hypoplasia, may occur either alone or in association with systemic conditions, like vertebral abnormalities or renal defects. All the cases with a mendelian inheritance are syndromic forms, which include cardiac defects (in Holt-Oram syndrome), bone marrow failure (in Fanconi anemia), platelet deficiency (in thrombocytopenia-absent-radius syndrome), ocular motility impairment (in Okihiro syndrome). The genetics of radial deficiencies is complex, characterized by genetic heterogeneity and high inter- and intra-familial clinical variability: this review will analyze the etiopathogenesis and the genotype/phenotype correlations of the main radial deficiency disorders in humans.

Hemifacial microsomia in cat-eye syndrome: 22q11.1-q11.21 as candidate loci for facial symmetry

Cat-Eye syndrome (CES), (OMIM 115470) also known as chromosome 22 partial tetrasomy or inverted duplicated 22q11, was first reported by Haab [1879] based on the primary features of eye coloboma and anal atresia. However, >60% of the patients lack these primary features. Here, we present a 9-month-old female who at birth was noted to have multiple defects, including facial asymmetry with asymmetric retrognathia, bilateral mandibular hypoplasia, branchial cleft sinus, right-sided muscular torticollis, esotropia, and an atretic right ear canal with low-to-moderate sensorineural hearing loss, bilateral preauricular ear tag/pits, and two skin tags on her left cheek. There were no signs of any colobomas or anal atresia. Hemifacial microsomia (HFM) was suspected clinically. Chromosome studies and FISH identified an extra marker originated from 22q11 consistent with CES, and this was confirmed by aCGH. This report expands the phenotypic variability of CES and includes partial tetrasomy of 22q11.1-q11.21 in the differential diagnosis of HFM. In addition, our case as well as the previous association of 22q11.2 deletions and duplications with facial asymmetry and features of HFM, supports the hypothesis that this chromosome region harbors genes important in the regulation of body plan symmetry, and in particular facial harmony.

Derivative 11;22 (emanuel) syndrome: a case report and a review

Emanuel syndrome (ES) is a rare anomaly characterized by a distinctive phenotype, consisting of characteristic facial dysmorphism, microcephaly, severe mental retardation, developmental delay, renal anomalies, congenital cardiac defects, and genital anomalies in boys. Here, we report a male neonate, with the classical features of Emanuel syndrome.

VATER/VACTERL Association: Evidence for the Role of Genetic Factors

The VATER/VACTERL association is typically defined by the presence of at least 3 of the following congenital malformations: Vertebral anomalies, Anal atresia, Cardiac malformations, Tracheo-Esophageal fistula, Renal anomalies, and Limb abnormalities. The involvement of genetic factors in the development of this rare association is suggested by reports of familial occurrence, the increased prevalence of component features among first-degree relatives of affected individuals, high concordance rates among monozygotic twins, chromosomal (micro-)aberrations or single gene mutations in individuals with the VATER/VACTERL phenotype, as well as murine knock-out models. Despite substantial efforts over the past decade, the genetic etiology of the VATER/VACTERL association in most instances remains elusive. The application of new genomic technologies such as high-resolution copy number variation studies or next-generation exome sequencing might lead to the identification of some of these causes.

VACTERL Association Etiology: The Impact of de novo and Rare Copy Number Variations

Copy number variations (CNVs), either DNA gains or losses, have been found at common regions throughout the human genome. Most CNVs neither have a pathogenic significance nor result in disease-related phenotypes but, instead, reflect the normal population variance. However, larger CNVs, which often arise de novo, are frequently associated with human disease. A genetic contribution has long been suspected in VACTERL (Vertebral, Anal, Cardiac, TracheoEsophageal fistula, Renal and Limb anomalies) association. The anomalies observed in this association overlap with several monogenetic conditions associated with mutations in specific genes, e.g. Townes Brocks (SALL1), Feingold syndrome (MYCN) or Fanconi anemia. So far VACTERL association has typically been considered a diagnosis of exclusion. Identifying recurrent or de novo genomic variations in individuals with VACTERL association could make it easier to distinguish VACTERL association from other syndromes and could provide insight into disease mechanisms. Sporadically, de novo CNVs associated with VACTERL are described in literature. In addition to this literature review of genomic variation in published VACTERL association patients, we describe CNVs present in 68 VACTERL association patients collected in our institution. De novo variations (>30 kb) are absent in our VACTERL association cohort. However, we identified recurrent rare CNVs which, although inherited, could point to mechanisms or biological processes contributing to this constellation of developmental defects.

De novo microduplications at 1q41, 2q37.3, and 8q24.3 in patients with VATER/VACTERL association

The acronym VATER/VACTERL association describes the combination of at least three of the following congenital anomalies: vertebral defects (V), anorectal malformations (A), cardiac defects (C), tracheoesophageal fistula with or without esophageal atresia (TE), renal malformations (R), and limb defects (L). We aimed to identify highly penetrant de novo copy number variations (CNVs) that contribute to VATER/VACTERL association. Array-based molecular karyotyping was performed in a cohort of 41 patients with VATER/VACTERL association and 6 patients with VATER/VACTERL-like phenotype including all of the patients' parents. Three de novo CNVs were identified involving chromosomal regions 1q41, 2q37.3, and 8q24.3 comprising one (SPATA17), two (CAPN10, GPR35), and three (EPPK1, PLEC, PARP10) genes, respectively. Pre-existing data from the literature prompted us to choose GPR35 and EPPK1 for mouse expression studies. Based on these studies, we prioritized GPR35 for sequencing analysis in an extended cohort of 192 patients with VATER/VACTERL association and VATER/VACTERL-like phenotype. Although no disease-causing mutation was identified, our mouse expression studies suggest GPR35 to be involved in the development of the VATER/VACTERL phenotype. Follow-up of GPR35 and the other genes comprising the identified duplications is warranted.

Prenatal screening characteristics in Emanuel syndrome: a case series and review of the literature

PURPOSE

Emanuel syndrome is a rare chromosomal disorder characterized by severe mental retardation and multiple anomalies. The syndrome is caused by chromosomal imbalance due to a supernumerary derivative chromosome 22. Little is known regarding the characteristics of prenatal biochemical screening, or ultrasonographic markers in this syndrome. We aimed to identify a prenatal screening pattern characteristic of Emanuel Syndrome.

METHODS

We report the prenatal characteristics of five fetuses with Emanuel syndrome, four of which were diagnosed prenatally.

RESULTS

We found no consistent pattern of prenatal biochemical markers or other prenatal characteristics. Nevertheless, increased NT, low PAPP-A and ultrasound features such as intra uterine growth restriction, posterior fossa, cardiac and bowel abnormalities may be helpful in raising the suspicion for this rare genetic syndrome.

CONCLUSION

Review of the biochemical screening results, ultrasound findings, and demographic characteristics of this Emanuel syndrome case series, as well as of the relevant literature fail to suggest a characteristic prenatal pattern.

Phenotypic delineation of Emanuel syndrome (supernumerary derivative 22 syndrome): Clinical features of 63 individuals

Emanuel syndrome is characterized by multiple congenital anomalies and developmental disability. It is caused by the presence of a supernumerary derivative chromosome that contains material from chromosomes 11 and 22. The origin of this imbalance is 3:1 malsegregation of a parental balanced translocation between chromosomes 11 and 22, which is the most common recurrent reciprocal translocation in humans. Little has been published on the clinical features of this syndrome since the 1980s and information on natural history is limited. We designed a questionnaire to collect information from families recruited through an international online support group, Chromosome 22 Central. Data gathered include information on congenital anomalies, medical and surgical history, developmental and behavioral issues, and current abilities. We received information on 63 individuals with Emanuel syndrome, ranging in age from newborn to adulthood. As previously recognized, congenital anomalies were common, the most frequent being ear pits (76%), micrognathia (60%), heart malformations (57%), and cleft palate (54%). Our data suggest that vision and hearing impairment, seizures, failure to thrive and recurrent infections, particularly otitis media, are common in this syndrome. Psychomotor development is uniformly delayed, however the majority of individuals (over 70%) eventually learn to walk with support. Language development and ability for self-care are also very impaired. This study provides new information on the clinical spectrum and natural history of Emanuel syndrome for families and physicians caring for these individuals.

Vertebral fusion in a patient with supernumerary-der(22)t(11;22) syndrome

A patient with a 47,XX,+der(22)t(11;22)(q23.3;q11.2) karyotype exhibited brisk tendon reflex and Babinski sign with suggested pyramidal sign. A three-dimensional computed tomographic reconstruction revealed a T1-T2 vertebral fusion without hemivertebrae. Sagittal magnetic resonance imaging revealed degenerative disk changes, mild disk herniation, and mild spinal cord compression. Congenital vertebral fusion may be one of the anomalies in supernumerary-der(22)t(11;22) syndrome. Once clinical diagnosis of this chromosome aberration is established, radiologic evaluation of vertebrae and spinal neuroimaging should be performed.

Genetic testing in other GI diseases

Gastrointestinal development is a complex process comprising folding of the endodermal layer to form the primitive gut tube, cell differentiation along its anteroposterior axis, the budding of the various organ primordia and development of derivative organs like the liver and pancreas and the colonisation of the gut with neuronal precursors. Genetic factors are increasingly recognised as playing a significant role in the disturbance of this developmental process which underlies congenital malformations and gastrointestinal disorders. Furthermore, genetic variation and its interaction with environmental influences play an important role in the pathogenesis of functional gastrointestinal disorders. In this review, we discuss the contribution of genetic variants, ranging from highly penetrant mutations and chromosomal abnormalities to genetic polymorphisms, to the pathogenesis of a number of structural and functional gastrointestinal disorders.

Mosaic trisomy 22 associated with total colonic aganglionosis and malrotation

AIMS

Abnormalities of chromosome 22 karyotype have been reported to be associated with both malrotation and aganglionosis. However, although malrotation has been reported to occur in the rare mosaic trisomy 22, Hirschsprung's disease has not. We present a case of mosaic trisomy 22 that presented during the neonatal period with malrotation and total colonic aganglionosis, and we discuss the possible pathogenesis of both conditions in the light of this rare genetic abnormality. The association of total colonic aganglionosis and mosaic trisomy 22 has not previously been reported.

RESULTS

A male neonate with an antenatal diagnosis of de novo mosaic trisomy 22 underwent a laparotomy with correction of malrotation and midgut volvulus on day 3 of life. Rectal biopsy was performed because he had not passed meconium. This revealed Hirschsprung's disease; an ileostomy was formed, and histology confirmed aganglionosis as far as the terminal ileum. At 6 months, a modified Lester Martin Duhamel pull-through was performed. He is showing normal development at follow-up.

CONCLUSIONS

We recommend an increased index of suspicion of Hirschsprung's disease and malrotation in patients with mosaic trisomy 22 until further evidence can establish or exclude a meaningful relationship.

Congenital bile duct anomalies (biliary atresia) and chromosome 22 aneuploidy

Biliary atresia is a disease of unknown etiology but not usually thought to have a significant genetic predisposition. We report 5 infants with various forms of chromosome 22 aneuploidy as follows: 2 infants who have classical cat-eye syndrome, 2 who have partial duplication of chromosome 22 (supernumerary der(22) syndrome), and 1 who is mosaic for trisomy 22. All of these infants had significant congenital bile duct anomalies (specifically biliary atresia, n = 4)-that was the most important component of their clinical presentation. We consider whether this has possible implications about the genetic contribution to the etiology of biliary atresia.