Skeletal anomalies and deformities in patients with deletions of 22q11

A regulatory variant impacting TBX1 expression contributes to basicranial morphology in Homo sapiens

Changes in gene regulatory elements play critical roles in human phenotypic divergence. However, identifying the base-pair changes responsible for the distinctive morphology of Homo sapiens remains challenging. Here, we report a noncoding single-nucleotide polymorphism (SNP), rs41298798, as a potential causal variant contributing to the morphology of the skull base and vertebral structures found in Homo sapiens. Screening for differentially regulated genes between Homo sapiens and extinct relatives revealed 13 candidate genes associated with basicranial development, with TBX1, implicated in DiGeorge syndrome, playing a pivotal role. Epigenetic markers and in silico analyses prioritized rs41298798 within a TBX1 intron for functional validation. CRISPR editing revealed that the 41-base-pair region surrounding rs41298798 modulates gene expression at 22q11.21. The derived allele of rs41298798 acts as an allele-specific enhancer mediated by E2F1, resulting in increased TBX1 expression levels compared to the ancestral allele. Tbx1-knockout mice exhibited skull base and vertebral abnormalities similar to those seen in DiGeorge syndrome. Phenotypic differences associated with TBX1 deficiency are observed between Homo sapiens and Neanderthals (Homo neanderthalensis). In conclusion, the regulatory divergence of TBX1 contributes to the formation of skull base and vertebral structures found in Homo sapiens.

Updated clinical practice recommendations for managing children with 22q11.2 deletion syndrome

This review aimed to update the clinical practice guidelines for managing children and adolescents with 22q11.2 deletion syndrome (22q11.2DS). The 22q11.2 Society, the international scientific organization studying chromosome 22q11.2 differences and related conditions, recruited expert clinicians worldwide to revise the original 2011 pediatric clinical practice guidelines in a stepwise process: (1) a systematic literature search (1992-2021), (2) study selection and data extraction by clinical experts from 9 different countries, covering 24 subspecialties, and (3) creation of a draft consensus document based on the literature and expert opinion, which was further shaped by survey results from family support organizations regarding perceived needs. Of 2441 22q11.2DS-relevant publications initially identified, 2344 received full-text reviews, including 1545 meeting criteria for potential relevance to clinical care of children and adolescents. Informed by the available literature, recommendations were formulated. Given evidence base limitations, multidisciplinary recommendations represent consensus statements of good practice for this evolving field. These recommendations provide contemporary guidance for evaluation, surveillance, and management of the many 22q11.2DS-associated physical, cognitive, behavioral, and psychiatric morbidities while addressing important genetic counseling and psychosocial issues.

Genetics of non-isolated hemivertebra: A systematic review of fetal, neonatal, and infant cases

Hemivertebra is a congenital vertebral malformation caused by unilateral failure of formation during embryogenesis that may be associated with additional abnormalities. A systematic review was conducted to investigate genetic etiologies of non-isolated hemivertebra identified in the fetal, neonatal, and infant periods using PubMed, Cochrane database, Ovid Medline, and ClinicalTrials.gov from inception through May 2022 (PROSPERO ID CRD42021229576). The Human Phenotype Ontology database was accessed May 2022. Studies were deemed eligible for inclusion if they addressed non-isolated hemivertebra or genetic causes of non-isolated hemivertebra identified in the fetal, neonatal, or infant periods. Cases diagnosed clinically without molecular confirmation were included. Systematic review identified 23 cases of non-isolated hemivertebra with karyotypic abnormalities, 2 cases due to microdeletions, 59 cases attributed to single gene disorders, 18 syndromic cases without known genetic etiology, and 14 cases without a known syndromic association. The Human Phenotype Ontology search identified 49 genes associated with hemivertebra. Non-isolated hemivertebra is associated with a diverse spectrum of cytogenetic abnormalities and single gene disorders. Genetic syndromes were notably common. Frequently affected organ systems include musculoskeletal, cardiovascular, central nervous system, genitourinary, gastrointestinal, and facial dysmorphisms. When non-isolated hemivertebra is identified on prenatal ultrasound, the fetus must be assessed for associated anomalies and genetic counseling is recommended.

Bi-allelic premature truncating variants in LTBP1 cause cutis laxa syndrome

Latent transforming growth factor β (TGFβ)-binding proteins (LTBPs) are microfibril-associated proteins essential for anchoring TGFβ in the extracellular matrix (ECM) as well as for correct assembly of ECM components. Variants in LTBP2, LTBP3, and LTBP4 have been identified in several autosomal recessive Mendelian disorders with skeletal abnormalities with or without impaired development of elastin-rich tissues. Thus far, the human phenotype associated with LTBP1 deficiency has remained enigmatic. In this study, we report homozygous premature truncating LTBP1 variants in eight affected individuals from four unrelated consanguineous families. Affected individuals present with connective tissue features (cutis laxa and inguinal hernia), craniofacial dysmorphology, variable heart defects, and prominent skeletal features (craniosynostosis, short stature, brachydactyly, and syndactyly). In vitro studies on proband-derived dermal fibroblasts indicate distinct molecular mechanisms depending on the position of the variant in LTBP1. C-terminal variants lead to an altered LTBP1 loosely anchored in the microfibrillar network and cause increased ECM deposition in cultured fibroblasts associated with excessive TGFβ growth factor activation and signaling. In contrast, N-terminal truncation results in a loss of LTBP1 that does not alter TGFβ levels or ECM assembly. In vivo validation with two independent zebrafish lines carrying mutations in ltbp1 induce abnormal collagen fibrillogenesis in skin and intervertebral ligaments and ectopic bone formation on the vertebrae. In addition, one of the mutant zebrafish lines shows voluminous and hypo-mineralized vertebrae. Overall, our findings in humans and zebrafish show that LTBP1 function is crucial for skin and bone ECM assembly and homeostasis.

Camptodactyly and DiGeorge syndrome: A rare hand anomaly

The most common deletion syndrome is 22q11.2 and it effects an estimated 1 in 3000 live births. Major features of this multisystem condition include congenital abnormalities, developmental delay, learning difficulties, immunodeficiency, endocrine anomalies and an array of psychiatric disorders. However, variability in phenotype and severity may cause the diagnosis to be overlooked. Early clinical recognition and treatment of DiGeorge syndrome has been shown to increase early life survival, decrease complications and enhance overall quality of life.

Skeletal anomalies are infrequently described in 22q11.2 but a subset of patients exhibit upper and lower limb deformities. We present the case of a 5 year-old girl with bilateral fifth digit camptodactyly caused by a fibrous band, and the surgical management of this condition. The current report adds to the body of evidence that camptodactyly is a rare clinical feature of 22q11.2 deletion syndrome, and may serve as a diagnostic aid in these patients.

What is new with 22q? An update from the 22q and You Center at the Children's Hospital of Philadelphia

22q11.2 deletion syndrome (22q11.2DS) is a disorder caused by recurrent, chromosome-specific, low copy repeat (LCR)-mediated copy-number losses of chromosome 22q11. The Children's Hospital of Philadelphia has been involved in the clinical care of individuals with what is now known as 22q11.2DS since our initial report of the association with DiGeorge syndrome in 1982. We reviewed the medical records on our continuously growing longitudinal cohort of 1,421 patients with molecularly confirmed 22q11.2DS from 1992 to 2018. Most individuals are Caucasian and older than 8 years. The mean age at diagnosis was 3.9 years. The majority of patients (85%) had typical LCR22A-LCR22D deletions, and only 7% of these typical deletions were inherited from a parent harboring the deletion constitutionally. However, 6% of individuals harbored other nested deletions that would not be identified by traditional 22q11.2 FISH, thus requiring an orthogonal technology to diagnose. Major medical problems included immune dysfunction or allergies (77%), palatal abnormalities (67%), congenital heart disease (64%), gastrointestinal difficulties (65%), endocrine dysfunction (>50%), scoliosis (50%), renal anomalies (16%), and airway abnormalities. Median full-scale intelligence quotient was 76, with no significant difference between individuals with and without congenital heart disease or hypocalcemia. Characteristic dysmorphic facial features were present in most individuals, but dermatoglyphic patterns of our cohort are similar to normal controls. This is the largest longitudinal study of patients with 22q11.2DS, helping to further describe the condition and aid in diagnosis and management. Further surveillance will likely elucidate additional clinically relevant findings as they age.

Scoliosis in association with the 22q11.2 deletion syndrome: an observational study

OBJECTIVE

The 22q11.2 deletion syndrome (22q11.2DS) is the most common microdeletion syndrome in humans. It is characterised by wide phenotypic variability, including congenital heart disease (CHD), immunodeficiency and scoliosis. However, little is known regarding the prevalence and characteristics of scoliosis in patients with 22q11.2DS. The objective of this study is to assess the prevalence of scoliosis, its characteristics and the association with CHD in patients with 22q11.2DS.

DESIGN

This prevalence study is based on physical examination and questionnaires of the world's largest 22q11.2DS longitudinal collected database (n=1393, Children's Hospital of Philadelphia) and was augmented with the scoliosis prevalence based on radiography in a smaller cohort (cross-sectional, University Medical Center Utrecht).

PATIENTS

Patients with a laboratory-confirmed 22q11.2 deletion who visited the specialised outpatient clinics were considered for inclusion.

MAIN OUTCOME MEASURES

(1) The prevalence of scoliosis, (2) its association with CHD, and (3) the similarity between 22q11.2DS curve patterns and adolescent idiopathic scoliosis (AIS) curve patterns.

RESULTS

Within the Philadelphia cohort, the prevalence of scoliosis in patients older than 16 years (n=317) was 48% (n=152). A similar prevalence (49%) was shown for the younger Utrecht cohort (n=97). The occurrence of scoliosis was not associated with the presence of CHD. Sixty-three per cent of patients with scoliosis had a scoliotic curve pattern that resembled AIS.

CONCLUSIONS

Clinicians should be aware that scoliosis is highly prevalent (48%-49%) in association with 22q11.2DS, irrespective of other clinical features (eg, the presence of CHD). Furthermore, 22q11.2DS may provide insights into the causes of AIS.

Novel heterozygous mutation in TBX1 in an infant with hypocalcemic seizures

Patients with 22q11.2 deletion syndrome have characteristic facial appearance, palate abnormalities, hypoparathyroidism, thymic hypoplasia, and congenital heart disease. The 22q11.2 region includes TBX1 and 30 other genes. Analysis of Tbx1 transgenic mice showed that TBX1 was associated with the 22q11.2 deletion syndrome. In humans, TBX1 mutations have been reported in 22q11.2 deletion-negative patients with velocardiofacial syndrome or DiGeorge syndrome. Genotype-phenotype correlations are not fully understood in these patients. We report the case of an infant with a novel heterozygous TBX1 mutation who experienced hypocalcemic seizures. This patient had no palate abnormalities, cardiac anomalies, or the typical facial appearance observed in 22q11.2 deletion syndrome. The presence of thymic hypoplasia prompted us to perform G-banding, fluorescent in situ hybridization, and subsequent TBX1 analysis. We emphasize the importance of diagnosing thymic hypoplasia in hypocalcemic infants without 22q11.2 deletion for detecting TBX1 mutations.

Expanding the fetal phenotype: Prenatal sonographic findings and perinatal outcomes in a cohort of patients with a confirmed 22q11.2 deletion syndrome

22q deletion syndrome (22q11.2DS) is most often correlated prenatally with congenital heart disease and or cleft palate. The extracardiac fetal phenotype associated with 22q11.2DS is not well described. We sought to review both the fetal cardiac and extracardiac findings associated with a cohort of cases ascertained prenatally, confirmed or suspected to have 22q11.2DS, born and cared for in one center. A retrospective chart review was performed on a total of 42 cases with confirmed 22q11.2DS to obtain prenatal findings, perinatal outcomes and diagnostic confirmation. The diagnosis was confirmed prenatally in 67% (28/42) and postnatally in 33% (14/42). The majority (81%) were associated with the standard LCR22A-LCR22D deletion. 95% (40/42) of fetuses were prenatally diagnosed with congenital heart disease. Extracardiac findings were noted in 90% (38/42) of cases. Additional findings involved the central nervous system (38%), gastrointestinal (14%), genitourinary (16.6%), pulmonary (7%), skeletal (19%), facial dysmorphism (21%), small/hypoplastic thymus (26%), and polyhydramnios (30%). One patient was diagnosed prenatally with a bilateral cleft lip and cleft palate. No fetus was diagnosed with intrauterine growth restriction. The average gestational age at delivery was 38 weeks and average birth weight was 3,105 grams. Sixty-two percentage were delivered vaginally and there were no fetal demises. A diagnosis of 22q11.2 deletion syndrome should be considered in all cases of prenatally diagnosed congenital heart disease, particularly when it is not isolated. Microarray is warranted in all cases of structural abnormalities diagnosed prenatally. Prenatal diagnosis of 22q11.2 syndrome can be used to counsel expectant parents regarding pregnancy outcome and guide neonatal management.

Congenital heart diseases and cardiovascular abnormalities in 22q11.2 deletion syndrome: From well-established knowledge to new frontiers

Congenital heart diseases (CHDs) and cardiovascular abnormalities are one of the pillars of clinical diagnosis of 22q11.2 deletion syndrome (22q11.2DS) and still represent the main cause of mortality in the affected children. In the past 30 years, much progress has been made in describing the anatomical patterns of CHD, in improving their diagnosis, medical treatment, and surgical procedures for these conditions, as well as in understanding the underlying genetic and developmental mechanisms. However, further studies are still needed to better determine the true prevalence of CHDs in 22q11.2DS, including data from prenatal studies and on the adult population, to further clarify the genetic mechanisms behind the high variability of phenotypic expression of 22q11.2DS, and to fully understand the mechanism responsible for the increased postoperative morbidity and for the premature death of these patients. Moreover, the increased life expectancy of persons with 22q11.2DS allowed the expansion of the adult population that poses new challenges for clinicians such as acquired cardiovascular problems and complexity related to multisystemic comorbidity. In this review, we provide a comprehensive review of the existing literature about 22q11.2DS in order to summarize the knowledge gained in the past years of clinical experience and research, as well as to identify the remaining gaps in comprehension of this syndrome and the possible future research directions.

Sleep Disturbances in 22q11.2 Deletion Syndrome: A Case with Obstructive and Central Sleep Apnea

The 22q11.2 deletion syndrome is characterized by wide phenotypic variability, frequently involving characteristic craniofacial features, cardiac malformations, and learning difficulties. Skeletal anomalies are also common and include an obtuse angle of the cranial base, retrognathia, and cervical spine abnormalities. Despite these anomalies, sleep-disturbed breathing is not reported frequently in patients with 22q11.2 deletion syndrome. We describe a patient with an obstructive sleep disturbance that was successfully treated with a tonsillectomy followed by mandibular distraction osteogenesis. She also had central sleep apnea, initially attributed to spinal cord impingement from cervical instability. Posterior cervical fusion was associated with a decrease in the number of central apneic events.

Development of a 22q11DS psycho-educational programme: exploration of the views, concerns and educational needs of parents caring for children or adolescents with 22q11DS in relation to mental health issues

BACKGROUND

22q11.2 deletion syndrome (22q11DS) is a multisystem genetic condition with a broad phenotype. It is associated with a high prevalence of depression and anxiety during childhood and increased risk of schizophrenia in adulthood. Despite this, studies report that families may receive inadequate information of mental health (MH) risks at diagnosis. Therefore, this study investigated parents' experiences of caring for a child with 22q11DS, investigated their knowledge regarding the risk of MH problems and assessed the need for a psycho-educational programme.

METHODS

A qualitative design and purposeful sampling was utilized. Parents registered with the '22q11 Ireland' support group, and parents listed on the cleft palate database in a children's hospital in Ireland were invited to participate. Focus groups were held with 22 parents. Data were thematically analysed using Burnard's method of analysis.

RESULTS

Most parents had some knowledge of the relationship between 22q11DS and an increased risk of MH issues. Parents reported that MH information relating to 22q11DS was mainly obtained from 22q11DS conferences, the '22q11 Ireland' support group and the Internet. Parents expressed a need for information to prevent or cope with their child's MH issues. Parents suggested that the following topics would be quite useful in a psycho-educational programme. These included information on the early warning signs of MH issues and guidance on when and how to tell the child about the condition and how to manage the child or young person's anxiety, obsessive behaviour or hearing voices.

CONCLUSIONS

The findings indicated parental support for a psycho-educational programme that would provide relevant, accurate and timely information on how to effectively care for a child with 22q11DS MH needs.

Camptodactyly and the 22q11.2 deletion syndrome

We describe a 5-day-old male with minor facial anomalies, a congenital laryngeal web, severe laryngomalacia, and prominent fixed flexion of the proximal interphalangeal joints of digits 2 through 5 bilaterally. A whole genome SNP microarray analysis identified a 2.55 Mb interstitial deletion of 22q11.21, typical of that seen in the DiGeorge and Velocardiofacial syndromes. A review of the literature identifies 10 other cases with camptodactyly. Camptodactyly appears to be an associated but rarely reported anomaly in patients with the 22q11.2 microdeletion syndrome. © 2016 Wiley Periodicals, Inc.

Differential diagnosis of multiple vertebral compression: butterfly vertebrae

[Purpose] A butterfly vertebra is a rare congenital anomaly resulting from a symmetric fusion defect. Only a few cases of butterfly vertebra have been described. This anomaly may be isolated or associated with Pfeiffer, Jarcho-Levins, Crouzon, or Alagille syndrome. [Subject and Methods] We herein describe a 38-year-old man who presented with neck and low back pain and was found to have butterfly vertebrae at the T9 and L3 levels. He also had Behçet’s disease and psoriasis. [Results] The patient’s symptoms improved with analgesics and physiotherapy. [Conclusion] To our knowledge, butterfly vertebrae at two levels have never been reported. Butterfly vertebrae may be confused with vertebral fractures in lateral radiographs, and awareness of this anomaly is important for a correct diagnosis.

Sprengel anomaly in deletion 22q11.2 (DiGeorge/Velo-Cardio-Facial) syndrome

Sprengel anomaly (SA) is a rare skeletal defect characterized by uni- or bi-lateral elevation of the scapula. This anomaly is often isolated, although it can occur in association with other defects, including cervical spine malformations, cleft palate, and facial anomalies. Neural crest migration anomalies have been involved in the etiology of SA. Since the same embryological pathway accounts for some of the clinical features of deletion 22q11.2 syndrome (del22q11.2; DiGeorge/Velo-Cardio-Facial syndrome), we investigated the occurrence of SA in a consecutive series of 235 del22q11.2 patients aged more than 2 years, undergoing a complete clinical and orthopedic assessment of the dorsal and thoracic skeleton. In the present series, two patients were diagnosed with true SA. Present results and published reports suggest that scapular involvement including SA occurs in 1-2% of del22q11.2 individuals. Accordingly, this anomaly should be investigated as one of the possible skeletal findings of del22q11.2 syndrome, while this diagnosis should be excluded in patients presenting with SA associated with other defects.

22q11.2 deletion syndrome

22q11.2 deletion syndrome (22q11.2DS) is the most common chromosomal microdeletion disorder, estimated to result mainly from de novo non-homologous meiotic recombination events occurring in approximately 1 in every 1,000 fetuses. The first description in the English language of the constellation of findings now known to be due to this chromosomal difference was made in the 1960s in children with DiGeorge syndrome, who presented with the clinical triad of immunodeficiency, hypoparathyroidism and congenital heart disease. The syndrome is now known to have a heterogeneous presentation that includes multiple additional congenital anomalies and later-onset conditions, such as palatal, gastrointestinal and renal abnormalities, autoimmune disease, variable cognitive delays, behavioural phenotypes and psychiatric illness - all far extending the original description of DiGeorge syndrome. Management requires a multidisciplinary approach involving paediatrics, general medicine, surgery, psychiatry, psychology, interventional therapies (physical, occupational, speech, language and behavioural) and genetic counselling. Although common, lack of recognition of the condition and/or lack of familiarity with genetic testing methods, together with the wide variability of clinical presentation, delays diagnosis. Early diagnosis, preferably prenatally or neonatally, could improve outcomes, thus stressing the importance of universal screening. Equally important, 22q11.2DS has become a model for understanding rare and frequent congenital anomalies, medical conditions, psychiatric and developmental disorders, and may provide a platform to better understand these disorders while affording opportunities for translational strategies across the lifespan for both patients with 22q11.2DS and those with these associated features in the general population.

Modeling a model: Mouse genetics, 22q11.2 Deletion Syndrome, and disorders of cortical circuit development

Understanding the developmental etiology of autistic spectrum disorders, attention deficit/hyperactivity disorder and schizophrenia remains a major challenge for establishing new diagnostic and therapeutic approaches to these common, difficult-to-treat diseases that compromise neural circuits in the cerebral cortex. One aspect of this challenge is the breadth and overlap of ASD, ADHD, and SCZ deficits; another is the complexity of mutations associated with each, and a third is the difficulty of analyzing disrupted development in at-risk or affected human fetuses. The identification of distinct genetic syndromes that include behavioral deficits similar to those in ASD, ADHC and SCZ provides a critical starting point for meeting this challenge. We summarize clinical and behavioral impairments in children and adults with one such genetic syndrome, the 22q11.2 Deletion Syndrome, routinely called 22q11DS, caused by micro-deletions of between 1.5 and 3.0 MB on human chromosome 22. Among many syndromic features, including cardiovascular and craniofacial anomalies, 22q11DS patients have a high incidence of brain structural, functional, and behavioral deficits that reflect cerebral cortical dysfunction and fall within the spectrum that defines ASD, ADHD, and SCZ. We show that developmental pathogenesis underlying this apparent genetic "model" syndrome in patients can be defined and analyzed mechanistically using genomically accurate mouse models of the deletion that causes 22q11DS. We conclude that "modeling a model", in this case 22q11DS as a model for idiopathic ASD, ADHD and SCZ, as well as other behavioral disorders like anxiety frequently seen in 22q11DS patients, in genetically engineered mice provides a foundation for understanding the causes and improving diagnosis and therapy for these disorders of cortical circuit development.

[Clubfoot's prenatal ultrasound diagnosis: is amniocentesis always warranted? About 124 cases]

OBJECTIVES

Analyze factors leading to isolated clubfoot's occurrence, identify clubfeet associated pathologies, and discuss the opportunity of performing an amniocentesis in cases of isolated clubfoot.

PATIENTS AND METHODS

Between January 2007 and December 2011, all patients diagnosed with clubfoot in our prenatal diagnostic center were retrospectively included. We then defined and analyzed idiopathic or isolated talipses equinovarus (ITEV) and clubfeet associated with others morphologic abnormalities or syndromic talipses equinovarus (STEV).

RESULTS

One hundred and twenty-four clubfeet were analyzed. Forty-seven cases of ITEV, for which 34 caryotypes were performed with a normal result. Risk factors of ITEV in our series were male gender (P=0.0017), a family history of clubfoot (P=0.001) and primiparity (P=0.04). Seventy-seven cases of STEV were diagnosed, 14 of which had chromosomal abnormalities, 18 spina bifida and 10 musculo-skeletal abnormalities. Among the 124 cases of clubfeet, 25 were unilateral and 99 were bilateral. Bilateral talipses equinovarus do not constitute a risk factor of STEV (P=0.8).

DISCUSSION AND CONCLUSION

We did not find any chromosomic abnormalities in cases of ITEV. The results of our study could lead to defer systematic amniocentesis in cases of primiparous women diagnosed with an ITEV, with a familial history of clubfoot and a male fetus. A referent echographist in prenatal diagnosis should still perform a systematic morphologic echography.

[Hand and endocrine diseases]

The whole of hormones likely influence state of hands, modifying colouring and trophicity of the skin and having influence on its muscular, tendineous, osseous, articular components. Thus state of the hands contributes to the recognition of the endocrine diseases: hot and moist hands of the Graves' disease, dry, cold and infiltrated hands in myxoedema, pale and fine hands of hypopituitarism, broad and thick hand of acromegaly, brachymetacarpia in the pseudohypoparathyroidism… Diabetes exposes particularly to tendineous and articular retractions, to whitlows and ungual mycosis.

Craniosynostosis and radial ray defect: a rare presentation of 22q11.2 deletion syndrome

A newborn with bilateral coronal craniosynostosis, hypoplastic thumbs, imperforate anus, and prenatal growth restriction was evaluated and given the clinical diagnosis of Baller-Gerold syndrome (BGS). While confirmatory testing of RECQL4 was pending, the infant developed unexplained hypocalcemia, prompting testing for a 22q11.2 deletion. Subsequently, the infant was found to have a 22q11.2 deletion, and was negative for an RECQL4 mutation. We therefore conclude that 22q11.2 deletion syndrome can present with findings resembling the BGS phenotype.

Persistent right aortic arch and associated axial skeletal malformations in cats

Persistent right aortic arch (PRAA) in cats is an uncommon vascular anomaly with clinical signs referable to oesophageal obstruction. To our knowledge no reports of axial skeletal malformations concomitant to PRAA have been reported in cats. The aim of this study is to depict a new clinical feature in cats affected by PRAA. In the study six cats with a diagnosis of vascular ring anomaly were enrolled. A complete physical examination, a neurological examination and a total body radiograph were performed on each animal. Four of the six cats showed contemporary PRAA and skeletal malformations. Additionally, for the first time, a genetic test was performed on one subject to detect DNA alterations in the homologous DiGeorge region of cat. The percentage of skeletal malformations reported in the normal population was compared with animals with PRAA and showed a higher frequency. Genetic testing failed to demonstrate a correlation between PRAA and DiGeorge genomic deletion. A review of veterinary and human diseases that presented both conditions was assessed. The few animals enrolled do not allow definitive conclusions. Further studies are required to corroborate the correlation between PRAA and axial skeletal malformations in cats.

Copy number analysis of 413 isolated talipes equinovarus patients suggests role for transcriptional regulators of early limb development

Talipes equinovarus is one of the most common congenital musculoskeletal anomalies and has a worldwide incidence of 1 in 1000 births. A genetic predisposition to talipes equinovarus is evidenced by the high concordance rate in twin studies and the increased risk to first-degree relatives. Despite the frequency of isolated talipes equinovarus and the strong evidence of a genetic basis for the disorder, few causative genes have been identified. To identify rare and/or recurrent copy number variants, we performed a genome-wide screen for deletions and duplications in 413 isolated talipes equinovarus patients using the Affymetrix 6.0 array. Segregation analysis within families and gene expression in mouse E12.5 limb buds were used to determine the significance of copy number variants. We identified 74 rare, gene-containing copy number variants that were present in talipes equinovarus probands and not present in 759 controls or in the Database of Genomic Variants. The overall frequency of copy number variants was similar between talipes equinovarus patients compared with controls. Twelve rare copy number variants segregate with talipes equinovarus in multiplex pedigrees, and contain the developmentally expressed transcription factors and transcriptional regulators PITX1, TBX4, HOXC13, UTX, CHD (chromodomain protein)1, and RIPPLY2. Although our results do not support a major role for recurrent copy number variations in the etiology of isolated talipes equinovarus, they do suggest a role for genes involved in early embryonic patterning in some families that can now be tested with large-scale sequencing methods.

A review of supernumerary and absent limbs and digits of the upper limb

For years people have been enamored by anomalies of the human limbs, particularly supernumerary and absent limbs and digits. Historically, there are a number of examples of such anomalies, including royal families of ancient Chaldea, tribes from Arabia, and examples from across nineteenth century Europe. The development of the upper limbs in a growing embryo is still being elucidated with the recent advent of homeobox genes, but researchers agree that upper limbs develop between stages 12-23 through a complex embryological process. Maternal thalidomide intake during limb development is known to cause limb reduction and subsequent amelia or phocomelia. Additionally, a number of clinical reports have illustrated different limb anomaly cases, with each situation unique in phenotype and developmental abnormality. Supernumerary and absent limbs and digits are not unique to humans, and a number of animal cases have also been reported. This review of the literature illustrates the historical, anatomical, and clinical aspects of supernumerary and absent limbs and digits for the upper limb.

Chromosome 22q11.2 deletion syndrome in African-American patients: a diagnostic challenge

Chromosome 22q11.2 deletion syndrome (22q11DS) is associated with numerous and variable clinical manifestations including conotruncal heart abnormalities, palatal anomalies, hypoparathyroidism, immune deficiency, and cognitive deficits. The clinical suspicion of this syndrome is often heightened by the presence of characteristic facial features. A previous report highlighted the under-diagnosis of this condition in African Americans, thought to be related to a paucity of typical facial features. We ascertained the largest cohort (n = 50) of African-American individuals with 22q11DS reported thus far, across five genetics centers in the United States and report on their facial and other phenotypic features. About 3/4 of our cohort has at least one dysmorphic facial feature. Auricular abnormalities, especially small ears, are the most common dysmorphic facial feature followed by nasal and ocular abnormalities. Skeletal findings are seen in about 2/3 of our cohort, higher than the typical frequency reported in 22q11DS. Cardiac anomalies, developmental delay, and palatal abnormalities are seen at a lower frequency in our cohort. Thus, it is evident that the features traditionally associated with 22q11DS are difficult to recognize in African-American individuals with this syndrome, due to both altered frequencies of major anomalies and a non-classic facial appearance. Therefore, a high index of suspicion is needed to recognize 22q11DS in African-American individuals.

Chromosome 22q11.2 deletion syndrome (DiGeorge syndrome/velocardiofacial syndrome)

Chromosome 22q11.2 deletion syndrome is a common syndrome also known as DiGeorge syndrome and velocardiofacial syndrome. It occurs in approximately 1:4000 births, and the incidence is increasing due to affected parents bearing their own affected children. The manifestations of this syndrome cross all medical specialties, and care of the children and adults can be complex. Many patients have a mild to moderate immune deficiency, and the majority of patients have a cardiac anomaly. Additional features include renal anomalies, eye anomalies, hypoparathyroidism, skeletal defects, and developmental delay. Each child's needs must be tailored to his or her specific medical problems, and as the child transitions to adulthood, additional issues will arise. A holistic approach, addressing medical and behavioral needs, can be very helpful.

Prenatal and postnatal diagnosis of 22q11.2 deletion syndrome

Microdeletion of chromosome 22q11.2, the most common human deletion syndrome encompasses a wide spectrum of abnormalities. Many clinical or ultrasonographic findings may support deletion studies, either in utero or in the post-natal period. The objective of our study was to evaluate the circumstances of 22q11.2 deletion diagnosis in a single centre of genetics during a 12 years period. Testing for 22q11.2 deletion was performed in 883 cases. Congenital heart defect was the most common reason for referral. An antenatal 22q11.2 microdeletion was detected in 8 fetuses (4.7%) among 169 pregnancies, all presenting conotruncal anomalies. In one case prenatal diagnosis led to the identification of the deletion in the mildly affected father and had negative impact on the family. During the same period, postnatal 22q11.2 DS was diagnosed in 81 out of 714 patients aged from birth to 42 years (11.3%) (p = 0.02). A CHD was present in 37 (45.7%). This figure is significantly lower than the 75% commonly reported. These results suggest that deletion studies could be justifiable in fetuses with non-cardiac prenatal sonographic findings that have been reported in association with 22q11.2 DS. However, as most of these malformations are rather common and non specific, systematic 22q11.2 testing is not justifiable. In such cases, careful cardiac and thymus examination could provide additional clues for 22q11.2 testing. In addition parents should be given accurate information before antenatal or postnatal testing, including the wide variability of the clinical phenotype, the impossibility to establish a precise prognosis concerning psychomotor development and psychiatric risks.

Syndromes of the first and second branchial arches, part 2: syndromes

A variety of congenital syndromes affecting the face occur due to defects involving the first and second BAs. Radiographic evaluation of craniofacial deformities is necessary to define aberrant anatomy, plan surgical procedures, and evaluate the effects of craniofacial growth and surgical reconstructions. High-resolution CT has proved vital in determining the nature and extent of these syndromes. The radiologic evaluation of syndromes of the first and second BA should begin first by studying a series of isolated defects (cleft lip with or without CP, micrognathia, and EAC atresia) that compose the major features of these syndromes and allow a more specific diagnosis. After discussion of these defects and the associated embryology, we discuss PRS, HFM, ACS, TCS, Stickler syndrome, and VCFS.

Three patients with oculo-auriculo-vertebral spectrum and microdeletion 22q11.2

We report on three unrelated patients with the 22q11.2 microdeletion syndrome (del22q11) who have phenotypic anomalies compatible with oculo-auriculo-vertebral spectrum (OAVS). Hemifacial microsomia, unilateral microtia, hearing loss, congenital heart/aortic arch arteries defects, and feeding difficulties were present in all three patients. Additional anomalies occasionally diagnosed included coloboma of the upper eyelid, microphthalmia, cerebral malformation, palatal anomalies, neonatal hypocalcemia, developmental delay, and laryngomalacia. Several clinical features characteristic of OAVS have been described in patients with del22q11 from the literature, including ear anomalies, hearing loss, cervical vertebral malformations, conotruncal cardiac defects, renal malformations, feeding and respiratory difficulties. Atretic ear with facial asymmetry has been previously described in one patient. Thus, clinical expression of hemifacial microsomia and microtia resembling OAVS should now be included within the wide phenotypic expression of del22q11. The occurrence of this manifestation in del22q11 is currently low. Nevertheless, patients with hemifacial microsomia and microtia associated with clinical features typically associated with del22q11 should now have for specific cytogenetic testing.

Butterfly vertebra: an uncommon congenital spinal anomaly

STUDY DESIGN

This is a report of a patient with T6 butterfly vertebra, which is an uncommon congenital spinal anomaly.

OBJECTIVE

To illustrate the significance of identifying butterfly vertebra that may be confused with other pathologic conditions like fractures, infections, and metastases.

SUMMARY OF BACKGROUND DATA

We report a 46-year-old woman with butterfly vertebra of T6 spine. The patient presented with complaints of low back pain and examination showed an abnormal bony prominence at midthoracic level. Radiologic and hematologic investigations confirmed the presence of butterfly vertebrae at T6 level, which proved to be a coincidental finding along with nonspecific low back pain. Knowledge about this condition is very important, since the condition can be easily confused with a pathologic fracture.

METHODS

The patient presented with a history of low back pain of 2 months. The patient was evaluated clinically and with hematological investigations. The diagnosis was confirmed with computerized tomography (CT) and magnetic resonance imaging (MRI) scans.

RESULTS

Routine examination of the motor and sensory system was found to be normal. Roentgenogram of the thoracic and lumbosacral spine showed anterior wedging of T6 vertebrae in the lateral view and features suggestive of the presence of a butterfly vertebra at T6 level in the anteroposterior (AP) view. Hematologic evaluation was done to rule out pathologic causes of anterior wedging of the vertebra like infections and metastases in the spine. MRI and CT scans of the spine confirmed the presence of T6 butterfly vertebra. Patient was treated for her low back pain and assured that the abnormal midthoracic bony prominence was a benign condition that needs no treatment.

CONCLUSION

A high index of suspicion is needed to identify this benign spinal anomaly that may be confused with many pathologic conditions. Knowledge of this condition helps in making rational use of extensive noninvasive and invasive diagnostic procedures.

Genetic counseling for the 22q11.2 deletion

Because of advances in palliative medical care, children with the 22q11.2 deletion syndrome are surviving into adulthood. An increase in reproductive fitness will likely follow necessitating enhanced access to genetic counseling for these patients and their families. Primary care physicians/obstetric practitioners are in a unique position to identify previously undiagnosed patients as they reach reproductive age and to refer them for genetic counseling. To date, most deletions are de novo, secondary to homologous recombination between low-copy repeat sequences located within 22q11.2. Nonetheless, both somatic and germ line mosaicism has been observed giving unaffected parents a small risk of recurrence. Once present though there is a 50% chance for a person with this contiguous deletion to have an affected child. With this in mind, a variety of prenatal monitoring techniques, as well as, preimplantation genetic diagnosis are available depending on the specific level of risk.

Advanced imaging of the cervical spine and spinal cord in 22q11.2 deletion syndrome: age-matched, double-cohort, controlled study

PURPOSE

The 22q11.2 deletion syndrome is a common genetic syndrome with a wide spectrum of abnormalities. We have previously described multiple anomalies of the upper cervical spine in this disorder. The objective of this study was to use advanced imaging to further define the morphology of the cervical spine and spinal cord in the 22q11.2 deletion syndrome, with a comparison to age-matched controls.

METHODS

A total of 32 patients with a 22q11.2 deletion underwent advanced imaging (computed tomography/magnetic resonance imaging; CT/MRI) of the cervical spine. In 27 patients, space available for the cord (SAC); the sagittal diameter of the vertebral body, spinal canal, cerebrospinal fluid (CSF), and spinal cord; and the cross sectional area of the spinal canal, CSF, and spinal cord were measured at each cervical level and compared to 29 age-matched controls. Statistical analysis was performed and potential implications were hypothesized.

RESULTS

In 22q11.2 patients, advanced imaging identified 40 pathologies not evident on plain radiographs with potential mechanical and/or neurological implications. These patients also had significantly smaller values (P </= 0.05) of the following parameters at one or more cervical levels, relative to age-matched controls: width of the vertebral body, spinal canal, CSF, and spinal cord; area of the spinal canal, CSF, and spinal cord. Neurologic symptoms were observed in 4/32 patients, with one patient requiring surgical intervention.

CONCLUSIONS

Advanced imaging of the cervical spine can detect findings not evident on plain radiographs in the 22q11.2 deletion syndrome. CT and/or MRI may be indicated when there is a high index of suspicion for clinical instability or neurologic compromise in order to rule out dynamic encroachment or impending neurologic sequelae. Spinal canal and spinal cord dimensions are reduced in these patients relative to controls with currently unknown clinical significance.

22q11 deletion syndrome: is that what they used to call . . . ?

PURPOSE

22q11 deletion syndrome (22q11DS) is a very common, but commonly overlooked, disorder that has many variable features, such as serious heart defects, speech and articulation problems, immune compromise, learning problems, pervasive developmental disorders, and a late appearing phenotype of this condition--mental illness.

CONCLUSION

Persons with 22q11DS are likely to be medically complex patients with pervasive developmental disorders and late appearing mental problems.

PRACTICE IMPLICATIONS

Establishing this diagnosis is useful to families and healthcare providers to anticipate and address immediate and future issues surrounding health promotion, disease prevention, and health maintenance.

Bilateral camptodactyly and recurrent patellar dislocation: a new sign of 22q11 deletions or an independent dominant disorder?

Three individuals from two families with bilateral camptodactyly and recurrent patellar subluxation are presented. All three have features of Di George syndrome owing to a 22q11 deletion. Hand abnormalities are infrequently seen in 22q11 deletions. Only one previous report exists of camptodactyly with patellar subluxation.

C1-2 vertebral anomalies in 22q11.2 microdeletion syndrome

BACKGROUND

Chromosome 22q11.2 microdeletion syndrome (22q11DS) is characterized by cleft palate, cardiac anomalies, characteristic facies, high prevalence of skeletal anomalies and learning disability.

OBJECTIVE

To evaluate the prevalence of craniovertebral junction anomalies in children with 22q11DS and compare these findings to those in nonsyndromic children with velopharyngeal insufficiency (VPI).

MATERIALS AND METHODS

Sequential CT scans performed for presurgical carotid assessment in 76 children (45 children positive for chromosome 22q11.2 deletion and 31 negative for the deletion) with VPI were retrospectively evaluated for assessment of C1-2 anomalies.

RESULTS

C1-2 vertebral anomalies, specifically midline C1 defects, uptilted or upswept posterior elements of C2 and fusions of C2-3, were nearly universal in our cohort of 22q11DS patients with VPI. They were strikingly absent in the majority of non-22q11DS patients with VPI.

CONCLUSION

C1-2 vertebral anomalies, particularly those listed above, are important radiographic markers for 22q11DS.

Expanding the phenotype of 22q11 deletion syndrome: the MURCS association

The MURCS association [Müllerian Duct aplasia or hypoplasia (M), unilateral renal agenesis (UR) and cervicothoracic somite dysplasia (CS)] manifests itself as Müllerian Duct aplasia or hypoplasia, unilateral renal agenesis and cervicothoracic somite dysplasia. We report on a 22-year-old woman with bicornuate uterus, right renal agenesis, C2-C3 vertebral fusion (MURCS association) and 22q11.2 deletion. Angio-MRI revealed the aberrant origin of arch arteries. Hashimoto thyroiditis, micropolycystic ovaries with a dermoid cyst in the right ovary and mild osteoporosis were also diagnosed. Accurate revision of radiographs enabled us also to identify thoracolumbar and lumbosacral vertebral-differentiation defects. Audiometry and echocardiogram were normal. Bone densitometry showed osteoporosis. As per our evaluation, the patient had short stature, obesity (BMI 30.7) and facial features suggestive of the 22q11 deletion syndrome. Multiplex ligation-dependent probe amplification analysis showed a de-novo 22q11.2 deletion confirmed by array-comparative genomic hybridization analysis. We discuss whether this is a casual association or whether it is an additional syndrome owing to the well known phenotype extensive variability of the 22q11 deletion syndrome.

22q11 deletion syndrome and limb anomalies: report on two Brazilian patients

OBJECTIVE

To report on two Brazilian patients with chromosome 22q11 deletion who presented with velopharyngeal insufficiency, congenital heart anomalies, developmental delay, and limb anomalies. The pattern of limb anomalies in these patients, which range from ectrodactyly to limb synostosis, is very uncommon in 22q11 deletion syndrome.

CONCLUSION

These patients widen the spectrum of clinical signs of the 22q11 deletion syndrome and alert researchers to conduct additional investigation in patients with limb involvement with velopharyngeal insufficiency and/or cardiac anomalies, along with developmental delay.

22q11.2 distal deletion: a recurrent genomic disorder distinct from DiGeorge syndrome and velocardiofacial syndrome

Microdeletions within chromosome 22q11.2 cause a variable phenotype, including DiGeorge syndrome (DGS) and velocardiofacial syndrome (VCFS). About 97% of patients with DGS/VCFS have either a common recurrent approximately 3 Mb deletion or a smaller, less common, approximately 1.5 Mb nested deletion. Both deletions apparently occur as a result of homologous recombination between nonallelic flanking low-copy repeat (LCR) sequences located in 22q11.2. Interestingly, although eight different LCRs are located in proximal 22q, only a few cases of atypical deletions utilizing alternative LCRs have been described. Using array-based comparative genomic hybridization (CGH) analysis, we have detected six unrelated cases of deletions that are within 22q11.2 and are located distal to the approximately 3 Mb common deletion region. Further analyses revealed that the rearrangements had clustered breakpoints and either a approximately 1.4 Mb or approximately 2.1 Mb recurrent deletion flanked proximally by LCR22-4 and distally by either LCR22-5 or LCR22-6, respectively. Parental fluorescence in situ hybridization (FISH) analyses revealed that none of the available parents (11 out of 12 were available) had the deletion, indicating de novo events. All patients presented with characteristic facial dysmorphic features. A history of prematurity, prenatal and postnatal growth delay, developmental delay, and mild skeletal abnormalities was prevalent among the patients. Two patients were found to have a cardiovascular malformation, one had truncus arteriosus, and another had a bicuspid aortic valve. A single patient had a cleft palate. We conclude that distal deletions of chromosome 22q11.2 between LCR22-4 and LCR22-6, although they share some characteristic features with DGS/VCFS, represent a novel genomic disorder distinct genomically and clinically from the well-known DGS/VCF deletion syndromes.

Velo-cardio-facial syndrome: 30 Years of study

Velo-cardio-facial syndrome is one of the names that has been attached to one of the most common multiple anomaly syndromes in humans. The labels DiGeorge sequence, 22q11 deletion syndrome, conotruncal anomalies face syndrome, CATCH 22, and Sedlacková syndrome have all been attached to the same disorder. Velo-cardio-facial syndrome has an expansive phenotype with more than 180 clinical features described that involve essentially every organ and system. The syndrome has drawn considerable attention because a number of common psychiatric illnesses are phenotypic features including attention deficit disorder, schizophrenia, and bipolar disorder. The expression is highly variable with some individuals being essentially normal at the mildest end of the spectrum, and the most severe cases having life-threatening and life-impairing problems. The syndrome is caused by a microdeletion from chromosome 22 at the q11.2 band. Although the large majority of affected individuals have identical 3 megabase deletions, less than 10% of cases have smaller deletions of 1.5 or 2.0 megabases. The 3 megabase deletion encompasses a region containing 40 genes. The syndrome has a population prevalence of approximately 1:2,000 in the United States, although incidence is higher. Although initially a clinical diagnosis, today velo-cardio-facial syndrome can be diagnosed with extremely high accuracy by fluorescence in situ hybridization and several other laboratory techniques. Clinical management is age dependent with acute medical problems such as congenital heart disease, immune disorders, feeding problems, cleft palate, and developmental disorders occupying management in infancy and preschool years. Management shifts to cognitive, behavioral, and learning disorders during school years, and then to the potential for psychiatric disorders including psychosis in late adolescence and adult years. Although the majority of people with velo-cardio-facial syndrome do not develop psychosis, the risk for severe psychiatric illness is 25 times higher for people affected with velo-cardio-facial syndrome than that of the general population. Therefore, interest in understanding the nature of psychiatric illness in the syndrome remains strong.

Craniosynostosis: another feature of the 22q11.2 deletion syndrome

We report on the presence of craniosynostosis in four patients with the 22q11.2 deletion. In light of previous reports of the association, we propose that the occurrence is higher than the general population incidence. Therefore, we suggest that craniosynostosis should be considered a manifestation of the 22q11.2 deletion and conversely that the 22q11.2 deletion should be considered in the differential diagnosis of craniosynostosis.

Presenting phenotype in 100 children with the 22q11 deletion syndrome

The aim of this study was to investigate and describe the presenting phenotype of children with the 22q11 deletion syndrome and to describe common clinical features that could serve as guidelines in the clinical diagnostic process preceding genetic testing. A hospital-based study of 100 consecutive children and adolescents with 22q11 deletion was initiated. The patients were divided into two groups according to age at diagnosis: before or after 2 years of age. Clinical features were grouped into a core set of eight features: cardiac defects, non-visible/hypoplastic thymus or infection problems, hypocalcaemia, feeding difficulties, cleft palate/speech-language impairment, developmental delay/learning difficulties, characteristic dysmorphic features and other malformations and deformities. The median age at diagnosis was 6.7 years. Of all patients, 26% were diagnosed in infancy and 92% had a congenital cardiac defect, whereas 54% of those diagnosed later had a cardiac defect. A cleft palate was present in 25 cases and 44 had some other malformation or deformity. All presented with a combination of many of the core features. Of those diagnosed after 2 years of age, the majority presented with speech-language impairment, developmental delay or learning difficulties and recurrent infections. Characteristic mild dysmorphic features were noticed in all children.

CONCLUSION

In spite of variable clinical expression, children with 22q11 deletion share a number of major features and have a characteristic phenotype. A high proportion have no cardiac defect and hence a risk of diagnostic delay. Increased awareness and knowledge among general paediatricians and other specialists who meet these children early in life is needed to reduce the diagnostic delay.

Radiographic study of the upper cervical spine in the 22q11.2 deletion syndrome

BACKGROUND

The chromosome abnormality, deletion of 22q11.2, is one of the most common genetic syndromes. The 22q11.2 deletion syndrome encompasses a wide spectrum of abnormalities including cardiac, palate, and immunological anomalies. The purposes of the current study were (1) to define and determine the frequency of variations of the occiput and cervical spine on plain radiographs in patients with the 22q11.2 deletion syndrome and (2) to postulate the potential clinical importance of these variations.

METHODS

Seventy-nine consecutive patients with the 22q11.2 deletion underwent clinical and radiographic evaluation of the occiput and cervical spine. Radiographic studies included lateral plain radiographs of the cervical spine in neutral, flexion, and extension; anteroposterior radiographs; and open-mouth odontoid radiographs.

RESULTS

At least one developmental variation of the occiput or cervical spine was observed in every patient. The occipital variations were platybasia in fifty-two (91%) of the fifty-seven patients for whom data were available and basilar impression in two (3%) of the seventy-nine patients. The atlas variations were dysmorphic shape in fifty-nine (75%) of the seventy-nine patients, open posterior arch in forty-seven (59%) of the seventy-nine patients, and occipitalization in two (3%) of the seventy-one patients with adequate radiographs. The axis variations were dysmorphic dens in forty-six (58%) and upswept lamina and posterior elements or "C2 swoosh" in forty-seven (59%) of the seventy-nine patients. Of the seventy-one patients with adequate radiographs, twenty-four (34%) had fusion of C2-C3, fifteen (21%) had fusion of the posterior elements only, and nine (13%) had a complete block fusion. Increased segmental motion was observed in forty (56%) of the seventy-one patients. Thirteen (33%) of the forty patients had increased segmental motion at more than one level. Thirty-one patients (44%) had increased occipitoatlantal motion, seven (10%) had increased atlantoaxial motion, and four had increased C2-C3 motion. Eleven (15%) of the seventy-one patients had increased C3-C4 mobility, always adjacent to a fusion of C2-C3.

CONCLUSIONS

Variations of the upper cervical spine, including increased segmental motion, are common in the 22q11.2 deletion syndrome. It is premature to predict the clinical implications of these radiographic findings, but advanced imaging and further observation may be needed to clarify their clinical course.

Consequences of JAG1 mutations

BACKGROUND

Alagille syndrome (AGS) is a multi-system, autosomal dominant disorder with highly variable expressivity, caused by mutations within the Jagged1 (JAG1) gene.

METHODS

We studied 53 mutation positive relatives of 34 AGS probands to ascertain the frequency of clinical findings in JAG1 mutation carriers.

RESULTS

Eleven of 53 (21%) mutation positive relatives had clinical features that would have led to a diagnosis of AGS. Seventeen of the 53 (32%) relatives had mild features of AGS, revealed only after targeted evaluation following the diagnosis of a proband in their family. Twenty five of the 53 (47%) mutation positive relatives did not meet clinical criteria, and two of these individuals had no features consistent with AGS at all. The frequency of cardiac and liver disease was notably lower in the relatives than in the probands, characterising the milder end of the phenotypic spectrum. The characteristic facies of AGS was the feature with the highest penetrance, occurring almost universally in mutation positive probands and relatives.

CONCLUSIONS

This study has implications for genetic counselling of families with AGS and JAG1 mutations.