Remote assessment of the Penn computerised neurocognitive battery in individuals with 22q11.2 deletion syndrome

BACKGROUND

Neurocognitive functioning is an integral phenotype of 22q11.2 deletion syndrome relating to severity of psychopathology and outcomes. A neurocognitive battery that could be administered remotely to assess multiple cognitive domains would be especially beneficial to research on rare genetic variants, where in-person assessment can be unavailable or burdensome. The current study compares in-person and remote assessments of the Penn computerised neurocognitive battery (CNB).

METHODS

Participants (mean age = 17.82, SD = 6.94 years; 48% female) completed the CNB either in-person at a laboratory (n = 222) or remotely (n = 162).

RESULTS

Results show that accuracy of CNB performance was equivalent across the two testing locations, while slight differences in speed were detected in 3 of the 11 tasks.

CONCLUSIONS

These findings suggest that the CNB can be used in remote settings to assess multiple neurocognitive domains.

An online survey to understand the needs of caregivers of family members with 22q11 deletion syndrome

BACKGROUND

Most individuals with 22q11.2 deletion syndrome (22q11DS) have multi-system and lifelong needs requiring substantial support. Their primary caregivers are usually family members who dedicate lifelong time and effort to their role. The pressures of their roles can negatively impact caregivers' psychosocial well-being, suggesting a need for additional support for this community who currently have no specialised interventions available.

METHOD

This online study surveyed 103 caregivers of family members with 22q11DS to determine the barriers to accessing support that they faced, the kind of support they would value and whether an online intervention could meet their needs.

RESULTS

The caregivers indicated that a brief online intervention focused on teaching practical skills and connecting them with a peer network of support would be most valuable.

CONCLUSIONS

Future studies are planned that will build on these results by designing and testing online interventions tailored to this community.

The COVID-19 pandemic's impact on worry and medical disruptions reported by individuals with chromosome 22q11.2 copy number variants and their caregivers

BACKGROUND

The world has suffered immeasurably during the COVID-19 pandemic. Increased distress and mental and medical health concerns are collateral consequences to the disease itself. The Genes to Mental Health (G2MH) Network consortium sought to understand how individuals affected by the rare copy number variations of 22q11.2 deletion and duplication syndrome, associated with neurodevelopmental/neuropsychiatric conditions, were coping. The article focuses on worry and disruptions in medical care caused by the pandemic.

METHODS

The University of Pennsylvania COVID-19 Stressor List and care disruption questions were circulated by 22 advocacy groups in English and 11 other languages.

RESULTS

A total of 512 people from 23 countries completed the survey; most were caregivers of affected individuals. Worry about family members acquiring COVID-19 had the highest average endorsed worry, whilst currently having COVID-19 had the lowest rated worry. Total COVID-19 worries were higher in individuals completing the survey towards the end of the study (later pandemic wave); 36% (n = 186) of the sample reported a significant effect on health due to care interruption during the pandemic; 44% of individuals (n = 111) receiving care for their genetic syndrome in a hospital setting reported delaying appointments due to COVID-19 fears; 12% (n = 59) of the sample reported disruptions to treatments; and of those reporting no current disruptions, 59% (n = 269) worried about future disruptions if the pandemic continued. Higher levels of care disruptions were related to higher COVID-19 worries (Ps < 0.005). Minimal differences by respondent type or copy number variation type emerged.

CONCLUSIONS

Widespread medical care disruptions and pandemic-related worries were reported by individuals with 22q11.2 syndrome and their family members. Reported worries were broadly consistent with research results from prior reports in the general population. The long-term effects of COVID-19 worries, interruptions to care and hospital avoidance require further study.

Anatomic Malformations of the Middle and Inner Ear in 22q11.2 Deletion Syndrome: Case Series and Literature Review

BACKGROUND AND PURPOSE

The 22q11.2 deletion syndrome is characterized by a heterogenic phenotype, including hearing loss. The underlying cause of hearing loss, especially sensorineural hearing loss, is not yet clear. Therefore, our objective was to describe anatomic malformations in the middle and inner ear in patients with 22q11.2 deletion syndrome.

MATERIALS AND METHODS

A retrospective case series was conducted in 2 tertiary referral centers. All patients with 22q11.2 deletion syndrome who had undergone CT or MR imaging of the temporal bones were included. Radiologic images were evaluated on predetermined parameters, including abnormalities of the ossicular chain, cochlea, semicircular canals, and vestibule.

RESULTS

There were 26 patients (52 ears) with a CT or MR imaging scan available. A dense stapes superstructure was found in 18 ears (36%), an incomplete partition type II was suspected in 12 cochleas (23%), the lateral semicircular canal was malformed with a small bony island in 17 ears (33%), and the lateral semicircular canal and vestibule were fused to a single cavity in 15 ears (29%).

CONCLUSIONS

Middle and inner ear abnormalities were frequently encountered in our cohort, including malformations of the lateral semicircular canal.

A neurogenetic model for the study of schizophrenia spectrum disorders: the International 22q11.2 Deletion Syndrome Brain Behavior Consortium

Rare copy number variants contribute significantly to the risk for schizophrenia, with the 22q11.2 locus consistently implicated. Individuals with the 22q11.2 deletion syndrome (22q11DS) have an estimated 25-fold increased risk for schizophrenia spectrum disorders, compared to individuals in the general population. The International 22q11DS Brain Behavior Consortium is examining this highly informative neurogenetic syndrome phenotypically and genomically. Here we detail the procedures of the effort to characterize the neuropsychiatric and neurobehavioral phenotypes associated with 22q11DS, focusing on schizophrenia and subthreshold expression of psychosis. The genomic approach includes a combination of whole-genome sequencing and genome-wide microarray technologies, allowing the investigation of all possible DNA variation and gene pathways influencing the schizophrenia-relevant phenotypic expression. A phenotypically rich data set provides a psychiatrically well-characterized sample of unprecedented size (n=1616) that informs the neurobehavioral developmental course of 22q11DS. This combined set of phenotypic and genomic data will enable hypothesis testing to elucidate the mechanisms underlying the pathogenesis of schizophrenia spectrum disorders.

Emergent, remitted and persistent psychosis-spectrum symptoms in 22q11.2 deletion syndrome

Individuals with 22q11.2 deletion syndrome (22q11DS) are at markedly elevated risk for schizophrenia-related disorders. Stability, emergence, remission and persistence of psychosis-spectrum symptoms were investigated longitudinally. Demographic, clinical and cognitive predictors of psychosis were assessed. Prospective follow-up over 2.8 years was undertaken in 75 individuals with 22q11DS aged 8-35 years. Mood, anxiety, attention-deficit hyperactivity disorders and psychosis-spectrum symptoms were assessed with the Kiddie-Schedule for Affective Disorders and Schizophrenia and Scale of Prodromal Symptoms (SOPS). Four domains of cognition were evaluated with the Penn Computerized Neurocognitive Battery (executive functioning, memory, complex cognition and social cognition). Psychotic disorder or clinically significant SOPS-positive ratings were consistently absent in 35%, emergent in 13%, remitted in 22% and persistent in 31% of participants. Negative symptoms and functional impairment were found to be predictive of the emergence of positive psychosis-spectrum symptoms and to reflect ongoing deficits after remission of positive symptoms. Dysphoric mood and anxiety were predictive of emergent and persistent-positive psychosis-spectrum symptoms. Lower baseline global cognition and greater global cognitive decline were predictive of psychosis-spectrum outcomes but no particular cognitive domain stood out as being significantly more discriminating than others. Our findings suggest that negative symptoms, functioning and dysphoric mood are important predictors of psychosis risk in this population.

Incidental radiologic findings in the 22q11.2 deletion syndrome

BACKGROUND AND PURPOSE

The 22q11.2 deletion syndrome is a common genetic microdeletion syndrome that results in cognitive delays and an increased risk of several psychiatric disorders, particularly schizophrenia. The current study investigates the prevalence of incidental neuroradiologic findings within this population and their relationships with psychiatric conditions.

MATERIALS AND METHODS

Brain MR imaging from 58 individuals with 22q11.2 deletion syndrome was reviewed by board-certified radiologists by using standard clinical procedures. Intracranial incidental findings were classified into 8 categories and compared with a large typically developing cohort.

RESULTS

The rate of incidental findings was significantly higher (P < .0001) in 22q11.2 deletion syndrome compared with typically developing individuals, driven by a high prevalence of cavum septum pellucidum (19.0%) and white matter abnormalities (10.3%). Both of these findings were associated with psychosis in 22q11.2 deletion syndrome.

CONCLUSIONS

Cavum septum pellucidum and white matter hyperintensities are significantly more prevalent in patients with the 22q11.2 deletion syndrome and may represent biomarkers for psychosis.

Psychiatric disorders in 22q11.2 deletion syndrome are prevalent but undertreated

BACKGROUND

Chromosome 22q11.2 deletion syndrome (22q11DS) is a common genetic disorder with high rates of psychosis and other psychopathologies, but few studies discuss treatment. Our aim was to characterize the prevalence and treatment of major psychiatric illnesses in a well-characterized sample of individuals with 22q11DS.

METHOD

This was a cross-sectional study of 112 individuals aged 8 to 45 years with a confirmed diagnosis of 22q11DS. Each participant was administered a modified Schedule for Affective Disorders and Schizophrenia for School-Age Children (K-SADS) and the Structured Interview for Prodromal Syndromes (SIPS). Phenotypes assessed were threshold and subthreshold psychosis, depression, mania, generalized and separation anxiety, obsessions/compulsions, inattention/hyperactivity and substance use. Histories of mental health care and current psychotropic treatment were obtained.

RESULTS

Psychopathology was common, with 79% of individuals meeting diagnostic criteria for a disorder at the time of assessment. Diagnoses of psychosis were made in 11% of cases, attenuated positive symptom syndrome (APS) in 21%, and 47% experienced significant subthreshold symptoms. Peak occurrence of psychosis risk was during adolescence (62% of those aged 12-17 years). Criteria for a mood disorder were met by 14%, for anxiety disorder 34% and for attention deficit hyperactivity disorder (ADHD) 31%. Mental health care had been received by 63% of individuals in their lifetime, but only 40% continued therapy and 39% used psychotropics. Antipsychotics were used by 42% of participants with psychosis and none of the participants with APS. Half of those at risk for psychosis were receiving no mental health care.

CONCLUSIONS

Psychopathology is common in 22q11DS but is not adequately treated or clinically followed. Particular attention should be paid to subthreshold psychotic symptoms, especially in adolescents.

More Clinical Overlap between 22q11.2 Deletion Syndrome and CHARGE Syndrome than Often Anticipated

CHARGE (coloboma, heart defects, atresia of choanae, retardation of growth and development, genital hypoplasia, and ear abnormalities) and 22q11.2 deletion syndromes are variable, congenital malformation syndromes that show considerable phenotypic overlap. We further explored this clinical overlap and proposed recommendations for the genetic diagnosis of both syndromes. We described 2 patients clinically diagnosed with CHARGE syndrome, who were found to carry a 22q11.2 deletion, and searched the literature for more cases. In addition, we screened our cohort of CHD7 mutation carriers (n = 802) for typical 22q11.2 deletion features and studied CHD7 in 20 patients with phenotypically 22q11.2 deletion syndrome but without haploinsufficiency of TBX1. In total, we identified 5 patients with a clinical diagnosis of CHARGE syndrome and a proven 22q11.2 deletion. Typical 22q11.2 deletion features were found in 30 patients (30/802, 3.7%) of our CHD7 mutation-positive cohort. We found truncating CHD7 mutations in 5/20 patients with phenotypically 22q11.2 deletion syndrome. Differentiating between CHARGE and 22q11.2 deletion syndromes can be challenging. CHD7 and TBX1 probably share a molecular pathway or have common target genes in affected organs. We strongly recommend performing CHD7 analysis in patients with a 22q11.2 deletion phenotype without TBX1 haploinsufficiency and conversely, performing a genome-wide array in CHARGE syndrome patients without a CHD7 mutation.

Clinical spectrum of SIX3-associated mutations in holoprosencephaly: correlation between genotype, phenotype and function

BACKGROUND

Holoprosencephaly (HPE) is the most common structural malformation of the human forebrain. There are several important HPE mutational target genes, including the transcription factor SIX3, which encodes an early regulator of Shh, Wnt, Bmp and Nodal signalling expressed in the developing forebrain and eyes of all vertebrates.

OBJECTIVE

To characterise genetic and clinical findings in patients with SIX3 mutations.

METHODS

Patients with HPE and their family members were tested for mutations in HPE-associated genes and the genetic and clinical findings, including those for additional cases found in the literature, were analysed. The results were correlated with a mutation-specific functional assay in zebrafish.

RESULTS

In a cohort of patients (n = 800) with HPE, SIX3 mutations were found in 4.7% of probands and additional cases were found through testing of relatives. In total, 138 cases of HPE were identified, 59 of whom had not previously been clinically presented. Mutations in SIX3 result in more severe HPE than in other cases of non-chromosomal, non-syndromic HPE. An over-representation of severe HPE was found in patients whose mutations confer greater loss of function, as measured by the functional zebrafish assay. The gender ratio in this combined set of patients was 1.5:1 (F:M) and maternal inheritance was almost twice as common as paternal. About 14% of SIX3 mutations in probands occur de novo. There is a wide intrafamilial clinical range of features and classical penetrance is estimated to be at least 62%.

CONCLUSIONS

Our data suggest that SIX3 mutations result in relatively severe HPE and that there is a genotype-phenotype correlation, as shown by functional studies using animal models.

Identification of a previously unrecognized microdeletion syndrome of 16q11.2q12.2

We report the identification of microdeletions of 16q11.2q12.2 by microarray-based comparative genomic hybridization (aCGH) in two individuals. The clinical features of these two individuals include hypotonia, gastroesophageal reflux, ear anomalies, and toe deformities. Other features include developmental delay, mental retardation, hypothyroidism, and seizures. The identification of common clinical features in these two individuals and those of one other report suggests microdeletion of 16q12.1q12.2 is a rare, emerging syndrome. These results illustrate that aCGH is particularly suited to identify rare chromosome abnormalities in patients with apparently non-syndromic idiopathic mental retardation and birth defects.

Overlapping numerical cognition impairments in children with chromosome 22q11.2 deletion or Turner syndromes

Children with one of two genetic disorders (chromosome 22q11.2 deletion syndrome and Turner syndrome) as well typically developing controls, participated in three cognitive processing experiments. Two experiments were designed to test cognitive processes involved in basic aspects numerical cognition. The third was a test of simple manual motor reaction time. Despite significant differences in global intellectual abilities, as measured by IQ tests, performance on the two numerical cognition tasks differed little between the two groups of children with genetic disorders. However, both performed significantly more poorly than did controls. The pattern of results are consistent with the hypothesis that impairments were not due to global intellectual ability but arose in specific cognitive functions required by different conditions within the tasks. The fact that no group differences were found in the reaction time task, despite significant differences in the standardized processing speed measure, further supports the interpretation that specific cognitive processing impairments and not global intellectual or processing speed impairments explain the pattern of results. The similarity in performance on these tasks of children with unrelated genetic disorders counters the view that numerical cognition is under any direct genetic control. Instead, our findings are consistent with the view that disturbances in foundational spatiotemporal cognitive functions contribute to the development of atypical representations and processes in the domains of basic magnitude comparison and simple numerical enumeration.

Molecular cytogenetic characterization of multiple intrachromosomal rearrangements of chromosome 2q in a patient with Waardenburg's syndrome and other congenital defects

At 6 years of age, a boy with bilateral sensorineural deafness, lateral displacement of inner canthi, a bulbous nasal tip, synophrys, and cryptorchidism was clinically diagnosed as having Waardenburg's syndrome type I (WS-1). In addition, he had a lumbar spina bifida with hydrocephalus shunted on the second day of life and severe mental retardation with a head circumference at the fifth percentile. Neither parent showed signs of WS-1, and the family history was negative. Because of the WS-1 features, attention was focused on the PAX3 location in 2q, at which time a de novo paracentric inversion of 2q23-q37.1 was noted. Subsequent high-resolution chromosome analysis 8 years later indicated a complex rearrangement involving regions 2q31-q35 and 2q13-q21. Whole chromosome painting and high-resolution comparative genomic hybridization yielded negative results for any translocation, duplication, or deletion of any chromosome segments. Sequencing of the PAX3 gene yielded no detectable mutation. Fluorescent in situ hybridization (FISH) studies with human BAC clones revealed five breakpoints in chromosome 2q resulting in two paracentric inversions and one insertion, the karyotype being interpreted as 46,XY,der(2)inv(2)(q13q21)inv(2)(q21q24.2)ins(2)(q24.2q33q35). In this extremely rare chromosomal rearrangement, the FISH result showed a breakpoint at 2q35 being proximal to and without involvement of the PAX3 gene. While further studies continue, possible interpretations include involvement of a regulatory gene(s) for PAX 3 and other genes at the other breakpoints related causally to the spina bifida and mental retardation.

Graves' disease in patients with 22q11.2 deletion

We report 4 female patients and 1 male patient with a 22q11.2 deletion and Graves' disease diagnosed at age 27 months, 7, 10, 17, and 16 years, respectively. The clinical presentations were typical for hyperthyroidism, but 1 female infant had seizures in addition to symptoms of hyperthyroidism. All patients had elevated serum levels of thyroid hormones in association with suppressed thyroid-stimulating hormone levels. From these observations, we suggest that Graves' disease may be a part of the clinical spectrum associated with the 22q11.2 deletion syndrome.

Bilateral microtia and cleft palate in cousins with Diamond-Blackfan anemia

We report on maternal first cousins with bilateral microtia, micrognathia, cleft palate and hematologic findings of Diamond-Blackfan anemia (DBA). The similarity of findings shared between our cases and a female reported by Hasan and Inoue [1993] suggests that this is a distinctive syndrome, rather than a chance association. DBA is a heterogeneous disorder, caused in about 25% of cases by heterozygous mutations in the RPS19 gene (DBA1). Mutation analysis in our cases did not show an RPS19 mutation, and 2 alleles were present in each. Segregation analysis for DBA1 on chromosome 19 and DBA2 on 8p23 was not consistent with linkage. We conclude that this syndrome of microtia, cleft palate and DBA is not allelic to known DBA loci.

The 22q11.2 deletion: screening, diagnostic workup, and outcome of results; report on 181 patients

A submicroscopic deletion of chromosome 22q11.2 has been identified in the majority of patients with the DiGeorge syndrome, velocardiofacial syndrome, conotruncal anomaly face syndrome, and in some patients with isolated conotruncal cardiac anomalies, Opitz G/BBB syndrome, and Cayler cardiofacial syndrome. We have evaluated 181 patients with this deletion. We describe our cohort of patients, how they presented, and what has been learned by having the same subspecialists evaluate all of the children. The results help define the extremely variable phenotype associated with this submicroscopic deletion and will assist clinicians in formulating a management plan based on these findings.

A diagnostic approach to identifying submicroscopic 7p21 deletions in Saethre-Chotzen syndrome: fluorescence in situ hybridization and dosage-sensitive Southern blot analysis

PURPOSE

To report on the use of fluorescence in situ hybridization (FISH) and dosage-sensitive Southern blot analysis in the molecular diagnosis of patients with Saethre-Chotzen syndrome.

METHODS

FISH and dosage-sensitive Southern blot analysis utilizing TWIST gene probes were performed on patients with Saethre-Chotzen syndrome but without an identifiable TWIST sequence variation.

RESULTS

Four unrelated patients with a deletion of the TWIST gene were identified by Southern blot; one of them had a complex chromosomal rearrangement involving 7p21 and no apparent deletion by FISH, suggesting a smaller deletion in the region including the TWIST gene. A fifth patient had an abnormal TWIST gene fragment on Southern blot analysis that segregated with the disease in the family; FISH was normal in this patient, suggesting a partial deletion or rearrangement in or near the gene.

CONCLUSION

FISH and dosage-sensitive Southern blot analysis are useful diagnostic tools in Saethre-Chotzen syndrome without TWIST sequence variation.

Phenotype of the 22q11.2 deletion in individuals identified through an affected relative: cast a wide FISHing net!

PURPOSE

The chromosome 22q11.2 deletion has been identified in the majority of patients with DiGeorge syndrome, velocardiofacial syndrome, and conotruncal anomaly face syndrome and in some patients with the autosomal dominant Opitz G/BBB syndrome and Cayler cardiofacial syndrome. In addition, 22q11.2 deletion studies are becoming part of a standardized diagnostic workup for some isolated defects such as conotruncal cardiac anomalies and velopharyngeal incompetence. However, there is little information available on the clinical findings of unselected patients. For example, those individuals identified during prenatal diagnosis, as part of a generalized screening protocol, or following the diagnosis in a relative. This information will be invaluable in defining the variability of the disorder and in observing long-term outcome in the absence of targeted remediations. This study allows one to examine the first unselected cohort of patients and serves to highlight the importance of deletion testing in parents of affected probands.

METHODS

Thirty individuals with a 22q11.2 deletion were identified following the diagnosis in a relative. Nineteen were adults ascertained only following the diagnosis in their child, 10 were children identified following the diagnosis in their sibling, and one was a child diagnosed prenatally following the diagnosis in her parent.

RESULTS

Sixty percent of patients had no visceral anomalies. In fact, only 6 of the 19 adults (32%) and 6 of the 11 children (55%) had major findings which would have brought them to medical attention. Deletion sizing demonstrated the same large 3-4 MB deletion in most families despite wide inter and intrafamilial variability and there was no difference in clinical findings based on the parent of origin. Thus, no genotype-phenotype correlations could be made.

CONCLUSION

We report the first unselected cohort of patients with the 22q11.2 deletion identified through an affected relative. Analysis of this series of 30 patients, many with very mild manifestations of the deletion, allows one to examine the outcome in individuals who lacked specific remediations for this disorder. It emphasizes the importance of broadening the index of suspicion in order to provide appropriate recurrence risk counseling, cognitive remediation, and medical management. Further, it underscores the lack of familial concordance and the current lack of genotype-phenotype correlations in this disorder, and it raises the possibility that the deletion is more common than previously reported.

Taking advantage of early diagnosis: preschool children with the 22q11.2 deletion

PURPOSE

The purpose of this study is to review the neurodevelopmental outcome of infants and preschoolers with a 22q11.2 microdeletion and to discuss the our clinical observations of clinical implications for educational and therapeutic interventions.

METHODS

One hundred twelve children (4 to 70 mos) with the 22q11.2 deletion were assessed using standardized tests (Bayley Scales of Infant Development-II, Preschool Language Scales, Wechsler Preschool and Primary Scales of Intelligence-Revised).

RESULTS

Fifty-four percent of the children were significantly delayed, 24% had mild delay, 22% had average cognitive development, and 80% were below average in language development. Delays are not explained by cardiac defects or palatal defects.

CONCLUSION

Developmental delays, mild hypotonia, language and speech delays, and feeding disorders are common, and this finding indicates the need for early intervention services beginning in infancy for children with the 22q11.2 deletion.

Communication issues in 22q11.2 deletion syndrome: children at risk

PURPOSE

The purpose of this investigation is to describe the communication profile of children with the 22q11.2 deletion syndrome from infancy through school age and to examine the influence of other medical aspects, such as palate anomalies, learning disorders, and cardiac defects of the syndrome to communication.

METHODS

Seventy-nine children were examined using standardized tests of speech and language and perceptual measures of resonance and voice.

RESULTS

Results show significant delay in emergence of speech and language milestones with delay/disorder in speech-language processes persisting into the school aged years, including those children diagnosed with nonverbal learning disabilities. Persistent articulation and resonance disorders were also present, presumed to be related in part to palatal anomalies. No correlation was found between cardiac status, learning disorders, palate anomalies and communication disorders.

CONCLUSION

The need for early identification and management of communication skills is crucial in the care of children with the 22q11.2 deletion.

Communication disorders in the 22Q11.2 microdeletion syndrome

The 22q11.2 microdeletion syndrome is a genetic disorder that is being recognized with increasing frequency. Confirmation of the diagnosis can be made using fluorescence in situ hybridization. Many medical and developmental problems are present in children with this syndrome. Communication disorders are among the most common features of this syndrome and include articulation, language, resonance, and voice problems. The purpose of this paper is to provide a description of the communicative and developmental features in a sample of children with the 22q11.2 microdeletion syndrome seen for evaluation. Because communication and feeding disorders may be presenting features of this syndrome, speech and language pathologists must be familiar with this syndrome and its various characteristics. Awareness of these features and a multidisciplinary approach are necessary for the identification and treatment of the complex communicative and medical problems present in this population.

Submicroscopic deletion in cousins with Prader-Willi syndrome causes a grandmatrilineal inheritance pattern: effects of imprinting

The Prader-Willi syndrome (PWS) critical region on 15q11-q13 is subject to imprinting. PWS becomes apparent when genes on the paternally inherited chromosome are not expressed. Familial PWS is rare. We report on a family in which a male and a female paternal first cousin both have PWS with cytogenetically normal karyotypes. Fluorescence in situ hybridization (FISH) analysis shows a submicroscopic deletion of SNRPN, but not the closely associated loci D15S10, D15S11, D15S63, and GABRB3. The cousins' fathers and two paternal aunts have the same deletion and are clinically normal. The grandmother of the cousins is deceased and not available for study, and their grandfather is not deleted for SNRPN. DNA methylation analysis of D15S63 is consistent with an abnormality of the imprinting center associated with PWS. "Grandmatrilineal" inheritance occurs when a woman with deletion of an imprinted, paternally expressed gene is at risk of having affected grandchildren through her sons. In this case, PWS does not become evident as long as the deletion is passed through the matrilineal line. This represents a unique inheritance pattern due to imprinting.

Chromosome 22-specific low copy repeats and the 22q11.2 deletion syndrome: genomic organization and deletion endpoint analysis

The 22q11.2 deletion syndrome, which includes DiGeorge and velocardiofacial syndromes (DGS/VCFS), is the most common microdeletion syndrome. The majority of deleted patients share a common 3 Mb hemizygous deletion of 22q11.2. The remaining patients include those who have smaller deletions that are nested within the 3 Mb typically deleted region (TDR) and a few with rare deletions that have no overlap with the TDR. The identification of chromosome 22-specific duplicated sequences or low copy repeats (LCRs) near the end-points of the 3 Mb TDR has led to the hypothesis that they mediate deletions of 22q11.2. The entire 3 Mb TDR has been sequenced, permitting detailed investigation of the LCRs and their involvement in the 22q11.2 deletions. Sequence analysis has identified four LCRs within the 3 Mb TDR. Although the LCRs differ in content and organization of shared modules, those modules that are common between them share 97-98% sequence identity with one another. By fluorescence in situ hybridization (FISH) analysis, the end-points of four variant 22q11.2 deletions appear to localize to the LCRs. Pulsed-field gel electrophoresis and Southern hybridization have been used to identify rearranged junction fragments from three variant deletions. Analysis of junction fragments by PCR and sequencing of the PCR products implicate the LCRs directly in the formation of 22q11.2 deletions. The evolutionary origin of the duplications on chromosome 22 has been assessed by FISH analysis of non-human primates. Multiple signals in Old World monkeys suggest that the duplication events may have occurred at least 20-25 million years ago.

Cognitive and behavior profile of preschool children with chromosome 22q11.2 deletion

A microscopic deletion of chromosome 22q11.2 has been identified in most patients with the DiGeorge, velocardiofacial syndrome, conotruncal anomaly face syndrome, and in some patients with isolated conotruncal cardiac anomalies. This study presents the neurodevelopmental outcome, including cognitive development, language development, speech, neuromuscular development, and behavioral characteristics of 40 preschool children (ages 13 to 63 months) who have been diagnosed with the 22q11.2 deletion. The impact of cardiac disease, cardiac surgery, and the palatal anomalies on this population was also studied. In the preschool years, children with a 22q11.2 deletion are most commonly found to be developmentally delayed, have mild hypotonia, and language and speech delays. The more significantly delayed children are at high risk to be subsequently diagnosed with mild or moderate mental retardation. The global delays and the variations in intelligence found are directly associated with the 22q11.2 deletion and are not explained by physical anomalies such as palatal defects or cardiac defects, or therapeutic interventions such as cardiac surgery. Our findings demonstrate that there is a pattern of significant speech disorders within this population. All of the children had late onset of verbal speech. Behavioral outcomes included both inhibition and attention disorders. Early intervention services are strongly recommended beginning in infancy to address the delays in gross motor skills, speech and language, and global developmental delays.

The Philadelphia story: the 22q11.2 deletion: report on 250 patients

A submicroscopic deletion of chromosome 22q11.2 has been identified in the majority of patients with the DiGeorge, velocardiofacial, and conotruncal anomaly face syndromes, and in some patients with the Opitz G/BBB and Cayler cardiofacial syndromes. We have been involved in the analysis of DiGeorge syndrome and related diagnoses since 1982 and have evaluated a large number of patients with the deletion. We describe our cohort of 250 patients whose clinical findings help to define the extremely variable phenotype associated with the 22q11.2 deletion and may assist clinicians in providing genetic counseling and guidelines for clinical management based on these findings.

Aphallia as part of urorectal septum malformation sequence in an infant of a diabetic mother

A male patient with aphallia, anal stenosis, tetralogy of Fallot, multiple vertebral anomalies including sacral agenesis and central nervous system (CNS) malformations was born after a pregnancy complicated by poorly controlled maternal diabetes. Aphallia is an extremely rare abnormality and can be part of the urorectal septum malformation sequence (URSMS). While aphallia has not been reported in infants of diabetic mothers, urogenital malformations are known to occur with increased frequency. Two female products of pregnancies complicated by diabetes presented with multiple malformations including anal atresia and recto-vaginal fistula consistent with the diagnosis of URSMS. The three patients share CNS, cardiac, and vertebral anomalies, abnormalities secondary to abnormal blastogenesis and characteristic of diabetic embryopathy. URSMS is also caused by abnormal blastogenesis. Therefore, this particular malformation should be viewed in the context of the multiple blastogenetic abnormalities in the cases reported here. The overlap of findings of URSMS in our cases with other abnormalities of blastogenesis, such as VATER association or sacral agenesis is not surprising, as these associations are known to lack clear diagnostic boundaries.

Psychoeducational profile of the 22q11.2 microdeletion: A complex pattern

OBJECTIVES

To examine the psychoeducational profile associated with the chromosome 22q11.2 microdeletion (DiGeorge/velocardiofacial syndrome).

STUDY DESIGN

Thirty-three patients (aged 6 to 27 years) with a 22q11.2 microdeletion underwent psychoeducational testing as part of a comprehensive evaluation. Nonparametric statistics were used to compare verbal and performance IQ, academic achievement scores, and receptive versus expressive language scores. Post hoc comparisons were made of IQ subtest scores and of language versus verbal IQ.

RESULTS

Full-scale IQ ranged from the normal to the moderately retarded range. Mean verbal IQ was significantly higher than mean performance IQ. In a similar manner, mean reading and spelling scores were superior to the mean mathematics score, although achievement scores typically were in the range of verbal IQ. In addition, many children showed clinically significant language impairments, with mean language scores lower than mean verbal IQ.

CONCLUSIONS

The IQ and academic profiles are reminiscent of a "nonverbal learning disability," although achievement was not discrepant from IQ. The coincidence of language impairment with a relative strength in reading belies a unique neuropsychologic profile. Educational programming for these children must address both verbal and nonverbal deficits.

De novo alu-element insertions in FGFR2 identify a distinct pathological basis for Apert syndrome

Apert syndrome, one of five craniosynostosis syndromes caused by allelic mutations of fibroblast growth-factor receptor 2 (FGFR2), is characterized by symmetrical bony syndactyly of the hands and feet. We have analyzed 260 unrelated patients, all but 2 of whom have missense mutations in exon 7, which affect a dipeptide in the linker region between the second and third immunoglobulin-like domains. Hence, the molecular mechanism of Apert syndrome is exquisitely specific. FGFR2 mutations in the remaining two patients are distinct in position and nature. Surprisingly, each patient harbors an Alu-element insertion of approximately 360 bp, in one case just upstream of exon 9 and in the other case within exon 9 itself. The insertions are likely to be pathological, because they have arisen de novo; in both cases this occurred on the paternal chromosome. FGFR2 is present in alternatively spliced isoforms characterized by either the IIIb (exon 8) or IIIc (exon 9) domains (keratinocyte growth-factor receptor [KGFR] and bacterially expressed kinase, respectively), which are differentially expressed in mouse limbs on embryonic day 13. Splicing of exon 9 was examined in RNA extracted from fibroblasts and keratinocytes from one patient with an Alu insertion and two patients with Pfeiffer syndrome who had nucleotide substitutions of the exon 9 acceptor splice site. Ectopic expression of KGFR in the fibroblast lines correlated with the severity of limb abnormalities. This provides the first genetic evidence that signaling through KGFR causes syndactyly in Apert syndrome.

TWIST gene mutation in a patient with radial aplasia and craniosynostosis: further evidence for heterogeneity of Baller-Gerold syndrome

The term Baller-Gerold syndrome was coined by Cohen [1979: Birth Defects 15(5B): 13-63] to designate the phenotype of craniosynostosis and radial aplasia. It is thought to be a rare autosomal recessive condition, which, in some patients, presents with additional abnormalities, such as polymicrogyria, mental retardation or anal atresia. A phenotypic overlap of Baller-Gerold and Roberts-SC phocomelia syndrome was noted when a patient with bicoronal synostosis and bilateral radial hypoplasia was found to have premature centromere separation, a finding characteristic of Roberts syndrome [Huson et al.,1990: J Med Genet 27:371-375]. Other cases of presumed Baller-Gerold syndrome were rediagnosed as Fanconi pancytopenia, Rothmund-Thomson syndrome or VACTERL association. These reports led to a narrowed redefinition of Baller-Gerold syndrome based on the exclusion of cytogenetic and hematopoetic abnormalities and the absence of additional malformations in patients with craniosynostosis and preaxial upper limb abnormalities. Here we report on a patient with unilateral radial aplasia and bicoronal synostosis without additional malformations and without chromosome breakage, who fits this narrow definition of Baller-Gerold syndrome. We identified a novel TWIST gene mutation in this patient, a Glu181Stop mutation predicting a premature termination of the protein carboxy-terminal to the helix 2 domain. This report provides further evidence that Baller-Gerold is of heterogeneous cause, and a thorough evaluation is indicated to identify a possibly more specific diagnosis, including Saethre-Chotzen syndrome. This differential diagnosis is of particular importance, as it is an autosomal dominant trait. Therefore, the recurrence risk for parents of an affected child can be 50% if one parent carries the mutation, as opposed to the 25% recurrence risk for autosomal recessive inheritance. Offspring of the affected patient also have a 50% risk to inherit the mutation, while the risk to bear an affected offspring for an autosomal recessive trait is very low.

Fibroblast growth factor homologous factor 2 (FHF2): gene structure, expression and mapping to the Börjeson-Forssman-Lehmann syndrome region in Xq26 delineated by a duplication breakpoint in a BFLS-like patient

Börjeson-Forssman-Lehmann syndrome (BFLS) is a syndromal X-linked mental retardation, which maps by linkage to the q26 region of the human X chromosome. We have identified a male patient with BFLS-like features and a duplication, 46,Y,dup(X)(q26q28), inherited from his phenotypically normal mother. Fluorescence in situ hybridisation using yeast artificial chromosome clones from Xq26 localised the duplication breakpoint to an approximately 400-kb interval in the Xq26.3 region between DXS155 and DXS294/DXS730. Database searches and analysis of available genomic DNA sequence from the region revealed the presence of the fibroblast growth factor homologous factor gene, FHF2, within the duplication breakpoint interval. The gene structure of FHF2 was determined and two new exons were identified, including a new 5' end exon, 1B. FHF2 is a large gene extending over approximately 200 kb in Xq26.3 and is composed of at least seven exons. It shows tissue-specific alternative splicing and alternative transcription starts. Northern blot hybridisation showed highest expression in brain and skeletal muscle. The FHF2 gene localisation and tissue-specific expression pattern suggest it to be a candidate gene for familial cases of the BFLS syndrome and other syndromal and non-specific forms of X-linked mental retardation mapping to the region.

Hemifacial microsomia in a newborn with hypoplastic skin lesions, an eyelid skin tag, and microphthalmia: an unusual presentation of Delleman syndrome

Delleman syndrome (oculocerebrocutaneous syndrome) is characterized by orbital cysts, periorbital skin appendages, and focal cutaneous hypoplasia. We describe a male infant with findings associated with this condition, including an eyelid appendage, discrete hypoplastic skin lesions, unilateral microphthalmia, and hydrocephalus. In addition, he had striking unilateral mandibular hypoplasia and microtia, features often present in the oculoauriculovertebral (OAV) spectrum. However, hypoplastic skin lesions and eyelid appendages are not features of the OAV spectrum. The marked degree of hemifacial microsomia present in this child has not been previously noted in Delleman syndrome. Two patients with Delleman syndrome have been previously described who have features typically present in the OAV spectrum. This case demonstrates that characteristics of both Delleman syndrome and the OAV spectrum may be present in one individual.

Phenotype of the fibroblast growth factor receptor 2 Ser351Cys mutation: Pfeiffer syndrome type III

We present a patient with pansynostosis, hydrocephalus, seizures, extreme proptosis with luxation of the eyes out of the lids, apnea and airway obstruction, intestinal non-rotation, and severe developmental delay. His skeletal abnormalities include bilateral elbow ankylosis, radial head dislocation, and unilateral broad and deviated first toe. The phenotype of this patient is consistent with that previously reported in Pfeiffer syndrome type III, but is unusual for the lack of broad thumbs. Our patient most closely resembles the case described by Kerr et al. [1996: Am J Med Genet 66:138-143] as Pfeiffer syndrome type III with normal thumbs. Mutations in the genes for fibroblast growth factor receptors (FGFR) 1 and 2 have previously been seen in patients with Pfeiffer syndrome type I. The mutation identified in our patient, Ser351Cys in FGFR2, represents the first reported cause of Pfeiffer syndrome type III. An identical mutation was described once previously by Pulleyn et al., in a patient whose brief clinical description included cloverleaf skull, significant developmental delay, and normal hands and feet [Eur. J. Hum. Genet. 4: 283-291, 1996]. In our patient, previously performed single-strand conformation polymorphism analysis failed to detect a band shift; the mutation was identified only after independent sequence analysis.

Increased prevalence of immunoglobulin A deficiency in patients with the chromosome 22q11.2 deletion syndrome (DiGeorge syndrome/velocardiofacial syndrome)

We wished to determine the prevalence of immunoglobulin A (IgA) deficiency in patients with the chromosome 22q11.2 deletion syndrome. A total of 32 patients with the chromosome 22q11.2 deletion were examined for IgA deficiency. We report a 13% (n = 4) prevalence of IgA deficiency in patients with this syndrome. The odds ratio of IgA deficiency in this population is 14.20 (P < 0.0001). This confirms the occurrence of significant humoral deficits in this predominantly cellular immunodeficiency.

Growth hormone deficiency in patients with 22q11.2 deletion: expanding the phenotype

The list of findings associated with the 22q11.2 deletion is quite long and varies from patient to patient. The hallmark features include: conoruncal cardiac anomalies, palatal defects, thymic aplasia or hypoplasia, T cell abnormalities, mild facial dysmorphia, and learning disabilities. The 22q11.2 deletion has been seen in association with the DiGeorge sequence, velocardiofacial syndrome (VCFS), conotruncal anomaly face syndrome, isolated conotruncal cardiac anomalies, and some cases of autosomal dominant Optiz G/BBB syndrome. Short stature has been seen in one to two thirds of children reported in the literature with a diagnosis of VCFS, but growth hormone deficiency (GHD) has not been described in conjunction with this diagnosis. We present 4 patients with a 22q11.2 deletion and short stature who were found to have abnormalities in the growth hormone-insulin-like growth factor I axis. All had growth factors less than -2 SD for age and failed provocative growth hormone testing. Two patients were found to have abnormal pituitary anatomy. In our population, the incidence of GHD in 4 or 95 children with 22q11 deletion is significantly greater than the estimated incidence of GHD in the general population. Children with a 22q11.2 deletion appear to be at a greater risk for pituitary abnormalities. Therefore, those children with the 22q11.2 deletion and short stature or poor growth should be evaluated for GHD, as replacement growth hormone therapy may improve their growth velocity and final height prediction.

Identification of a genetic cause for isolated unilateral coronal synostosis: a unique mutation in the fibroblast growth factor receptor 3

To determine whether the autosomal dominant fibroblast growth factor receptor 3 (FGFR3) Pro250Arg mutation causes anterior plagiocephaly, patients with either apparently sporadic unicoronal synostosis (N = 37) or other forms of anterior plagiocephaly (N = 10) were studied for this mutation. Of 37 patients with unicoronal synostosis, 4 tested positive for the Pro250Arg mutation in FGFR3, and 33 were negative for this mutation. In three mutation positive patients with full parental studies, a parent with an extremely mild phenotype was found to carry the same mutation. None of the 6 patients with nonsynostotic plagiocephaly and none of the 4 patients with additional suture synostosis had the FGFR3 mutation. Because it is impossible to predict the FGFR3 Pro250Arg mutation status based on clinical examination alone, all patients with unicoronal synostosis should be tested for it. To assess their recurrence risk, all parents of mutation positive patients should be tested regardless of their clinical findings, because the phenotype can be extremely variable and without craniosynostosis.

Lack of correlation between impaired T cell production, immunodeficiency, and other phenotypic features in chromosome 22q11.2 deletion syndromes

Monosomic deletions of chromosome 22q11.2 are the leading cause of DiGeorge syndrome, velocardiofacial syndrome, and conotruncal anomaly face syndrome. DiGeorge syndrome was originally described as an immunodeficiency disorder secondary to impaired T cell production due to thymic aplasia or hypoplasia; however, the frequency of immunodeficiency in the other clinical syndromes associated with the chromosome 22q11.2 microdeletion has not been previously investigated. This study examines the frequency and severity of impaired T cell production and immunodeficiency in chromosome 22q11.2 deletion syndromes and the relationship of the immunodeficiency to specific phenotypic features. Sixty patients over 6 months of age with the characteristic chromosome 22q11.2 deletion underwent immunologic evaluations. Seventy-seven percent of patients with chromosome 22q11.2 deletions were found to have evidence of immunocompromise. The severity of the immunodeficiency did not correlate with any particular phenotypic feature, nor was it restricted to patients who were categorized as having DiGeorge syndrome. Therefore, impaired T cell production and impaired immunologic function are common in patients with deletions of chromosome 22q11.2. The presence or severity of the immunocompromise cannot be predicted based on other phenotypic features and each child should be individually assessed for immune function.

Heterotaxia in a fetus with campomelia, cervical lymphocele, polysplenia, and multicystic dysplastic kidneys: expanding the phenotype of Cumming syndrome

We report on a fetus with tetramelic campomelia, polysplenia, multicystic dysplastic kidneys, and cervical lymphocele. This condition is similar to the autosomal recessive condition described by Cumming et al. [1986: Am J Med Genet 25:783-790] and is different from campomelic syndrome. In addition, our case had anomalies not previously described in this condition, including abnormal lung lobation with bilateral left bronchial morphology, dextrocardia, total anomalous pulmonary venous return, a left superior vena cava, and a right aortic arch. The pancreas was short, with absence of the body and tail. These anomalies are similar to those found in the polyasplenia spectrum. We suggest that the syndrome reported by Cumming et al. may be expanded to include polysplenia with heterotaxia and that Cumming syndrome may be considered another autosomal recessive condition associated with a laterality defect.

Skeletal anomalies and deformities in patients with deletions of 22q11

Skeletal anomalies in patients with a 22q11.2 deletion are reported infrequently. We report the skeletal findings in 108 patients with a 22q11.2 deletion, of whom 37 (36%) had a skeletal anomaly. Twenty-two patients (20%) had anomalies of the limbs, 7 of the upper limb, including preaxial or postaxial polydactyly. An anomaly of the lower limb was found in 16 patients, including postaxial polydactyly, clubfoot, severely overfolded toes, and 2-3 toe cutaneous syndactyly. Chest films of 63 patients were examined; 30% of them had abnormal findings, most commonly supernumerary ribs (17%) or a "butterfly" vertebral body (11%). Hypoplastic vertebrae, hemivertebrae, and vertebral coronal clefts were also noted. Thus, skeletal anomalies are not uncommon in patients with a 22q11.2 deletion and may occur more frequently than recognized previously.

Neuropathological findings in eight children with cerebro-oculo-facio-skeletal (COFS) syndrome

Cerebro-oculo-facial-skeletal (COFS) syndrome is a rare autosomal recessive disorder with microcephaly, severe mental retardation, and death in childhood. The pathogenesis is unknown. Neuropathological features of 8 children with COFS syndrome are presented. Seven of the children, ranging in age from 36 weeks gestation to 5 years 8 months, are of North American aboriginal background from Manitoba, Canada. The eight child is a 3-year-old Caucasian male. In all children there was severe microencephaly and mild ventriculomegaly. Cerebral myelination appeared to be delayed in one infantile case. Swollen ubiquitinated granular cells appeared in the white matter shortly after birth. Older children displayed cortical neuron loss, patchy or diffuse absence of myelin and gliosis in the white matter, and pericapillary and parenchymal mineralization in the globus pallidus and to a lesser extent the putamen and cerebral cortex. The cerebellum of older children exhibited severe degenerative changes involving the internal granular layer and Purkinje cell layer. The neuropathological changes, previously not well documented, suggest that COFS syndrome is associated with a degenerative process that begins in utero and affects many brain cell types. Similarities to Cockayne syndrome are discussed.

Further clinical delineation and increased morbidity in males with osteopathia striata with cranial sclerosis: an X-linked disorder?

Osteopathia striata with cranial sclerosis (OS-CS) is a bone dysplasia characterized by hypertelorism, macrocephaly, frontal bossing, broad nasal bridge, palate anomalies, hearing deficits, and mental retardation. The radiographic findings include cranial sclerosis, linear striations in the long bones and iliac wings, small poorly aerated sinuses, scoliosis, and increased bone density. The sensory deficits are disabling, but the condition generally is not life threatening. We describe 4 brothers with the characteristics of OS-CS, 3 of whom have died from more serious complications of the disorder. The mother of these children, and her only daughter, have the mildest phenotype with the typical linear striations in the long bones and macrocephaly. OS-CS is thought to be autosomal dominant with complete penetrance and variable expressivity. Our observations could be consistent with X-linkage, since there is milder expression in the female relatives. In addition, we recognize absent fibulae, malrotation, and omphalocele as new manifestations as well as congenital heart disease.

Detection of a 22q11.2 deletion in cardiac patients suggests a risk for velopharyngeal incompetence

OBJECTIVE

Conotruncal cardiac anomalies frequently occur in patients with DiGeorge or velocardiofacial syndrome. Additionally, these patients may have overt or submucousal cleft palate, as well as velopharyngeal incompetence (VPI). Previous studies have demonstrated that the majority of these patients have a submicroscopic deletion of chromosome 22q11.2. We hypothesized that a subpopulation of newborns and children with congenital heart defects caused by a 22q11.2 deletion are at a high risk for having unrecognized palatal abnormalities. Therefore, we proposed to evaluate a cohort of patients with conotruncal cardiac malformations associated with a 22q11.2 deletion to determine the frequency of palatal abnormalities.

METHODS

We identified 14 deletion-positive patients with congenital cardiac defects who had no overt cleft palate. Of the 14 patients evaluated for the 22q11.2 deletion, 8 patients were recruited from a previous study looking for deletions among patients with isolated conotruncal cardiac anomalies. Informed consent was obtained in these cases. The remaining patients had the deletion study on a clinical basis, ie, conotruncal cardiac defect and an absent thymus, immunodeficiency, or minor dysmorphia appreciated by the clinical geneticist. These patients were evaluated by a plastic surgeon and speech pathologist looking for more subtle palatal anomalies such as a submucousal cleft palate, absence of the musculous uvuli, and VPI. Some patients underwent videofluoroscopy or nasendoscopy depending on their degree of symptoms and age. VPI was not ruled out until objective evaluation by a speech pathologist and plastic surgeon was obtained. In addition, the child had to be old enough to provide an adequate speech sample.

RESULTS

Of the 14 patients evaluated, 6 patients older than 1 year were found to have VPI. It is noteworthy that 3 of these patients were older than 5 years and had remained unrecognized until this study. The remaining 6 patients had inconclusive studies based on their age (younger than 26 months) and their inability to participate in adequate speech evaluations. Two of these patients, however, had histories of nasal regurgitation suggesting VPI and, in addition, had incomplete closure of the velopharyngeal mechanism during crying and swallowing observed during nasendoscopic examination-consistent with the diagnosis of VPI. Thus, 8 of 14 patients evaluated had evidence of VPI by history and examination. The remaining 6 patients will require further study when they are older before a definitive palatal diagnosis can be made.

CONCLUSIONS

A significant number of patients with a 22q11.2 deletion in a cardiac clinic may have unrecognized palatal problems. Recognition of such abnormalities will afford patients the opportunity for intervention as needed, ie, speech therapy and/or surgical intervention. Notably, two of our patients with findings suggesting VPI were infants and will, therefore, be afforded the opportunity for close follow-up and early intervention. Furthermore, three school-aged children had palatal abnormalities that were unrecognized until this study. Thus, we recommend 22q11.2 deletion studies in patients with conotruncal cardiac malformations, followed by extensive palatal and speech evaluations when a deletion is present.

Sibs with cleidocranial dysplasia born to normal parents: germ line mosaicism?

Cleidocranial dysplasia (CCD) is classically an autosomal dominant disorder. However, the possibility of an autosomal recessive form of CCD has been suggested based on a report of 2 consanguineous families, one with a single affected child, the second with affected sibs, born to normal parents. We present a family with sibs with CCD born to normal parents, and suggest germ line mosaicism as the more likely mechanism for this occurrence.

Nasal dimple as part of the 22q11.2 deletion syndrome

The phenotype of the 22q11.2 microdeletion syndrome is quite variable. We describe 2 patients with a 22q11.2 deletion and a dimpled nasal tip, which, we suggest can be the extreme of the broad or bulbous nose commonly found in the 22q11.2 deletion syndrome, and should not be confused with the more severe nasal abnormalities seen in frontonasal dysplasia.

Juvenile rheumatoid arthritis-like polyarthritis in chromosome 22q11.2 deletion syndrome (DiGeorge anomalad/velocardiofacial syndrome/conotruncal anomaly face syndrome)

OBJECTIVE

To investigate the association of polyarthritis and chromosome 22q11.2 deletions.

METHODS

Eighty patients with chromosome 22q11.2 deletion syndrome followed up at The Children's Hospital of Philadelphia were examined for evidence of arthropathy or arthritis. Patients with chromosome 22q11.2 deletion syndrome and polyarthritis underwent laboratory evaluations of immunologic function to determine the relationship of their immunodeficiency to the polyarthritis.

RESULTS

The prevalence of polyarthritis in patients with chromosome 22q11.2 deletion syndrome was markedly increased over the prevalence of polyarticular juvenile rheumatoid arthritis (JRA) in the general population. All 3 patients with polyarthritis had evidence of impaired T cell function. Two of the patients with polyarthritis also had IgA deficiency.

CONCLUSION

The chromosome 22q11.2 deletion syndrome represents a primary T cell disorder which can be associated with a JRA-like polyarthritis. All 3 patients with polyarthritis had evidence of more extensive immunoregulatory derangements than those typically seen in patients with chromosome 22q11.2 deletion, and these derangements may have predisposed to the development of polyarthritis.

Disruption of the clathrin heavy chain-like gene (CLTCL) associated with features of DGS/VCFS: a balanced (21;22)(p12;q11) translocation

The smallest region of deletion overlap in the patients we have studied defines a DIGeorge syndrome/velocardiofacial syndrome (DGS/VCFS) minimal critical region (MDGCR) of approximately 250 kb within 22q11. A de novo constitutional balanced translocation has been identified within the MDGCR. The patient has some features which have been reported in individuals with DGS/VCFS, including: facial dysmorphia, mental retardation, long slender digits and genital anomalies. We have cloned the breakpoint of his translocation and shown that it interrupts the clathrin heavy chain-like gene (CLTCL) within the MDGCR. The breakpoint of the translocation partner is in a repeated region telomeric to the rDNA cluster on chromosome 21p. Therefore, it is unlikely that the patient's findings are caused by interruption of sequences on 21p. The chromosome 22 breakpoint disrupts the 3' coding region of the CLTCL gene and leads to a truncated transcript, strongly suggesting a role for this gene in the features found in this patient. Further, the patient's partial DGS/VCFS phenotype suggests that additional features of DGS/VCFS may be attributed to other genes in the MDGCR. Thus, haploinsufficiency for more than one gene in the MDGCR may be etiologic for DGS/VCFS.

A unique point mutation in the fibroblast growth factor receptor 3 gene (FGFR3) defines a new craniosynostosis syndrome

The underlying basis of many forms of syndromic craniosynostosis has been defined on a molecular level. However, many patients with familial or sporadic craniosynostosis do not have the classical findings of those craniosynostosis syndromes. Here we present 61 individuals from 20 unrelated families where coronal synostosis is due to an amino acid substitution (Pro250Arg) that results from a single point mutation in the fibroblast growth factor receptor 3 gene on chromosome 4p. In this instance, a new clinical syndrome is being defined on the basis of the molecular finding. In addition to the skull findings, some patients had abnormalities on radiographs of hands and feet, including thimble-like middle phalanges, coned epiphyses, and carpal and tarsal fusions. Brachydactyly was seen in some cases; none had clinically significant syndactyly or deviation of the great toe. Sensorineural hearing loss was present in some, and developmental delay was seen in a minority. While the radiological findings of hands and feet can be very helpful in diagnosing this syndrome, it is not in all cases clearly distinguishable on a clinical basis from other craniosynostosis syndromes. Therefore, this mutation should be tested for in patients with coronal synostosis.