The origin of inverted tandem duplications, and phenotypic effects of tandem duplication of the X chromosome long arm

Delineation of an inverted tandem Xq23-26.3 duplication in a female featuring extremely short stature and mild mental deficiency

BACKGROUND

Partial duplications involving the long arm of the X chromosome are associated with mental retardation, short stature, microcephaly, and a wide range of physical findings. Female carriers usually have no clinical phenotype. Occasionally, they may also have heterogeneous features due to non-random inactivation of the X chromosome.

METHODS

The peripheral blood sample was collected from the patient and subjected to a few genetic testing, including chromosomal karyotyping, Chromosomal microarray analysis (CMA), Optical genome mapping, short tandem repeat (STR) analysis for Determination of parental origin, and X chromosome inactivation (XCI) analysis.

RESULTS

We have identified a de novo Xq23-Xq26.3 duplication in an adult female featuring extremely short stature and mild mental deficiency. Chromosome analysis detected a duplication on Xq23-q26.3 with a size of approximately 20 Mb. The duplication region has encompassed a number of genes, among which ARHGEF6, PHF6, HPRT1 and SLC9A6 are associated with X-linked mental retardation. Further analysis suggested that the duplication has derived from her father, was of the inversion duplication type and involved various degrees of skewed X chromosome inactivation.

CONCLUSION

Correlation with her phenotypes might indicate new mechanisms by which the X chromosome may lead to short stature and mental retardation. Our findings thereby may shed more light on the phenotypic implication of functional disomy of X-chromosome genes.

A novel de novo partial xq duplication in a girl with short stature, nonverbal learning disability and diminished ovarian reserve - effect of growth hormone treatment and fertility preservation strategies: a case report and up-to-date review

Background

Xq duplication is a rare condition with a very variable phenotype, which could mimic other genetic syndromes involving the long arm of chromosome X. Sometimes short stature and diminished ovarian reserve (DOR) may be present. Treatments with rGH (Recombinant growth Hormon) or with fertility preservation strategies have not been previously described.

Case presentation

We present the case of a female with a novel de novo Xq partial duplication (karyotype: 46,Xder(X)(qter→q21.31::pter→qter) confirmed by array-CGH analysis. She presented with short stature, Nonverbal Learning Disability, developmental delay during childhood, severe scoliosis, spontaneous onset of menarche and irregular menstrual cycles. AMH (Anti-Müllerian Hormone) allowed detection of a preserved but severely diminished ovarian reserve with a POI (Premature Ovarian insufficiency) onset risk. She was effectively subjected to fertility preservation strategies and rGH therapy. We also reviewed other published cases with Xq duplication, reporting the main clinics characteristics and any adopted treatment.

Conclusions

rGH treatment and cryopreservation in a multidisciplinary approach are good therapeutic strategies for Xq duplication syndrome with short stature and premature ovarian failure.

Delineating the Clinical Spectrum Associated With Xq25q26.2 Duplications: Report of 2 Families and Review of the Literature

To date, 13 patients with interstitial microduplications involving Xq25q26.2 have been reported. Here, we report 6 additional patients from 2 families with duplications involving Xq25q26.2. Family I carries a 5.3-Mb duplication involving 26 genes. This duplication was identified in 3 patients and was associated with microcephaly, growth failure, developmental delay, and dysmorphic features. Family II carries an overlapping 791-kb duplication that involves 3 genes. This duplication was identified in 3 patients and was associated with learning disability and speech delay. The size and gene content of published overlapping Xq25q26.2 duplications vary, making it difficult to define a critical region or establish a genotype-phenotype correlation. However, patients with overlapping duplications have been found to share common clinical features including microcephaly, growth failure, intellectual disability, learning difficulties, and dysmorphic features. The 2 families presented here provide additional insight into the phenotypic spectrum and clinical significance of duplications in this region.

Trisomy Xp and partial tetrasomy Xq resulting from gain of a rearranged X chromosome in a female fetus: pathogenic or not?

Cytogenetic analysis of chorionic villous sampling revealed a mosaic karyotype with gain of a rearranged X chromosome. Microarray and additional studies indicated that the rearranged X carried an inverted duplication, a deletion and a satellited Xqter. Gain of this rearranged X was confirmed by follow-up amniocentesis and postnatal cord blood sample. A full-term infant girl was delivered and showed normal physical findings at both birth and 21-month follow-up examinations. Late replication studies demonstrated that the rearranged X was inactivated in all abnormal cells analyzed. Skewed X-inactivation may suppress the potentially deleterious effects of genomic imbalance; however, gain of X chromosomes, particularly rearranged X chromosomes, often presents challenges for prenatal genetic counseling. The gradation of clinical phenotype severity generally correlates with the number of additional X chromosomes. However, the X chromosome regions responsible for the abnormal phenotypes are poorly understood. This case will further elucidate the phenotypic effects of X inactivation and X chromosome abnormalities.

De novo duplication of Xq22.1→q24 with a disruption of the NXF gene cluster in a mentally retarded woman with short stature and premature ovarian failure

OBJECTIVE

To present molecular cytogenetic characterization of a de novo duplication of Xq22.1→q24 in a mentally retarded woman with short stature and premature ovarian failure.

MATERIALS AND METHODS

A 19-year-old woman presented with psychomotor retardation, developmental delay, mental retardation, short stature, low body weight, general muscle hypotonia, distal muscle hypotrophy of the lower extremities, elongated digits, scanty pubic and axillary hair, hypoplastic external female genitalia, and secondary amenorrhea but no clinical features of Pelizaeus-Merzbacher disease. Conventional cytogenetic analysis revealed a karyotype of 46,X,dup(X)(q22.1q24). Fluorescence in situ hybridization determined a direct duplication with a linear tandem orientation. Array comparative genomic hybridization demonstrated partial trisomy Xq [arr cgh Xq22.1q24 (101,490,234-119,070,188 bp)×3] with a 17.6-Mb duplication.

RESULTS

The duplicated region contained NXF2B, NXF4, NXF3, PLP1, and PGRMC1 genes. There was a disruption of the NXF gene cluster of Xcen-NXF5-NXF2-NXF2B-NXF4-NXF3-Xqter.

CONCLUSION

A duplication of Xq22.1→q24 with a disruption of the NXF gene cluster in female patients can be associated with clinical manifestations of mental retardation in addition to short stature and premature ovarian failure.

Molecular cytogenetic characterisation of a mosaic add(12)(p13.3) with an inv dup(3)(q26.31 --> qter) detected in an autistic boy

BACKGROUND

Inverted duplications (inv dup) of a terminal chromosome region are a particular subset of rearrangements that often results in partial tetrasomy or partial trisomy when accompanied by a deleted chromosome. Associated mosaicism could be the consequence of a post-zygotic event or could result from the correction of a trisomic conception. Tetrasomies of distal segments of the chromosome 3q are rare genetic events and their phenotypic manifestations are diverse. To our knowledge, there are only 12 cases reported with partial 3q tetrasomy. Generally, individuals with this genomic imbalance present mild to severe developmental delay, facial dysmorphisms and skin pigmentary disorders.

RESULTS

We present the results of the molecular cytogenetic characterization of an unbalanced mosaic karyotype consisting of mos 46,XY,add(12)(p13.3) [56]/46,XY [44] in a previously described 11 years old autistic boy, re-evaluated at adult age. The employment of fluorescence in situ hybridization (FISH) and multicolor banding (MCB) techniques identified the extra material on 12p to be derived from chromosome 3, defining the additional material on 12p as an inv dup(3)(qter --> q26.3::q26.3 --> qter). Subsequently, array-based comparative genomic hybridization (aCGH) confirmed the breakpoint at 3q26.31, defining the extra material with a length of 24.92 Mb to be between 174.37 and 199.29 Mb.

CONCLUSION

This is the thirteenth reported case of inversion-duplication 3q, being the first one described as an inv dup translocated onto a non-homologous chromosome. The mosaic terminal inv dup(3q) observed could be the result of two proposed alternative mechanisms. The most striking feature of this case is the autistic behavior of the proband, a characteristic not shared by any other patient with tetrasomy for 3q26.31 --> 3qter. The present work further illustrates the advantages of the use of an integrative cytogenetic strategy, composed both by conventional and molecular techniques, on providing powerful information for an accurate diagnosis. This report also highlights a chromosome region potentially involved in autistic disorders.

Two Patients with X Chromosome Duplication: dupXp and dupXq

Structural abnormalities of the X chromosome may lead to different phenotypes, depending on the chromosome region affected. We report phenotypic findings of two patients who had X chromosome duplications. One had a menstrual irregularity, a low hairline, cubitus valgus and suffered from dyslexia. The other had multiple congenital anomalies, severe mental-motor retardation and intractable epilepsy. The karyotypes were 46,X,dup(X) (p11.3p21) and 46,X,dup(X)(q13q25) respectively.

A familial inverted duplication/deletion of 2p25.1-25.3 provides new clues on the genesis of inverted duplications

We studied a family in which the same 10 Mb inverted duplication of 2p25.3-p25.1 segregates in two children and their father, all showing a trisomy phenotype. As FISH analysis demonstrated that the duplication was inverted, we suspected that a contiguous terminal deletion was also present, according to the classical inv dup del type of rearrangements. Although FISH with 2p and 2q subtelomeric probes gave normal results, 100 kb resolution array-C/GH (aCGH) showed that, beside the duplication, a 273 kb deletion was also present. The presence of a single-copy region between the deleted and duplicated regions was further suspected through high-resolution aCGH analysis (approximately 20 kb), although only one informative spot having a normal log ratio was detected. The precise structure of the rearrangement was re-defined by real-time PCR and breakpoint cloning, demonstrating the presence of a 2680 bp single-copy sequence between deleted and duplicated regions and the involvement of a simple repeat with the potential for forming a non-B DNA structure. The rearrangement was not mediated by segmental duplications or short inverted repeats, and the double-strand break might have been repaired by non-homologous end joining or microhomology-mediated intrastrand repair. These data highlight the fact that concomitant deletions associated with inverted duplications are very likely to be more frequent than classical cytogenetic methods alone have been able to demonstrate. The phenotypic effects of the trisomy and of the terminal 2p deletion are discussed.

Partial Xp11.23-p11.4 duplication with random X inactivation: clinical report and molecular cytogenetic characterization

Partial duplications of the short arm of the X chromosome are relatively rare and have been described in males and females. We describe a 4 10/12-year-old girl presenting with developmental delay, severe language retardation and minor anomalies with slightly elevated head circumference (+1.8 SD), prominent forehead, wide palpebral fissures and anteverted nares. No pigmentary dysplasia of the skin was present. The external genitalia were normal. The karyotype completed by cytogenetic analysis with the Whole Chromosome Painting probe of chromosome X revealed a de novo partial duplication of the short arm of an X chromosome. In order to further characterize the duplicated segment, we used a series of BAC probes extending from band Xp11.22 to Xp22.1. BACs from Xp11.23 to Xp11.4 were duplicated. The karyotype was finally defined as 46,X,dup(X)(p11p11).ish dup(X)(p11.23p11.4)(WCPX+,RP11-416I6++,RP11-386N14++,RP11-466C12++). The X-inactivation status was studied using the human androgen receptor (HUMARA) and the FRAXA locus methylation assay. Unexpectedly, the two X chromosomes were found to be randomly inactivated, in the proband. Indeed, usually, in women with structurally abnormal X chromosome, the abnormal X chromosome is preferentially inactivated and those patients share an apparent normal phenotype. So, we speculate that in the present case, the phenotype of the patient could be explained by a functional disomy of the genes present in the duplicated region. We will discuss the possible implication of these genes on the observed phenotype.

De novo interstitial direct duplication of Xq21.1q25 associated with skewed X-inactivation pattern

Genotype-phenotype correlation in women with an abnormal phenotype associated with a duplication of the long arm of the X chromosome remains unclear. We report on prenatal diagnosis and follow-up of a girl with an Xq duplication and dysmorphic features. The abnormal phenotype included growth retardation, hypotonia, and nystagmus. In order to improve the resolution of the cytogenetic analysis, we used both conventional and array-based comparative genomic hybridization to perform a global molecular cytogenetic analysis of the genome. These molecular cytogenetic analyses showed a direct duplication Xq21.1 --> q25 without other chromosomal abnormalities. This duplication was originating from the paternal X chromosome. Moreover, a skewed X-inactivation pattern was observed leading to a partial functional disomy of the chromosomal region Xq21.1q25. This report and review of the literature suggest that functional disomy for chromosome X could explain the abnormal phenotype. In prenatal diagnosis, this can have implication for patient management and genetic counseling.

A 2.3 Mb duplication of chromosome 8q24.3 associated with severe mental retardation and epilepsy detected by standard karyotype

Chromosome duplications are found in about 2% of subjects with a typical chromosomal phenotype but their frequency is likely to be higher, as suggested by the first array-CGH data. According to the orientation of the duplicated segment, duplications may be in tandem or inverted. The latter are usually associated with a distal deletion. We studied a de novo 2.3 Mb inverted duplication of 8q24.3 without apparently associated deletion in a subject with profound psychomotor retardation, idiopathic epilepsy and growth delay. In spite of its small size, the presence of the rearrangement was suspected on standard karyotypes (approximately 400 bands) and later confirmed by Fluorescent in situ hybridization (FISH) analysis. We hypothesize that the GRINA gene, a glutamate binding subunit of NMDA receptor ion channel lying within the duplicated segment, may be responsible for the epilepsy. This paper confirms that small subtelomeric de novo duplications may be responsible for mental retardation, facial dysmorphisms and/or congenital malformations, although their presence may be overlooked by FISH analysis.

Xq chromosome duplication in males: Clinical, cytogenetic and array CGH characterization of a new case and review

Males with duplications within the long arm of the X chromosome are rare and most cases are inherited from a maternal heterozygote. We report a male with a de novo Xq duplication and review of the literature. The proband was ascertained prenatally after an abnormal expanded alpha-fetoprotein (AFP) screen and abnormal ultrasound findings. Chromosome analysis on amniocyte and subsequent peripheral blood lymphocyte cultures showed a male karyotype containing additional material on the long arm of the X chromosome. Fluorescence in situ hybridization with an X chromosome whole chromosome paint probe showed that the additional material was derived from the X chromosome, interpreted as a dup(X)(q13.3q24). Further characterization of the duplication by array CGH showed a duplication size between 30-44 Mb as determined by the map position of the flanking clones on the array, and refined the breakpoints of the duplicated region to Xq21.32 --> Xq25. At birth, the proband had multiple craniofacial abnormalities, musculoskeletal anomalies, bilateral cryptorchidism with scrotal hypoplasia, conductive hearing loss, and profound generalized hypotonia despite normal birthweight, length, and head circumference. Although data regarding Xq duplications in males are limited, a clear pattern of characteristic features can be discerned as illustrated in the present case and confirmed in our literature review. Mental, psychomotor and growth retardation, as well as, craniofacial anomalies, muscle hypotonia, hypoplastic genitalia, cryptorchidism, feeding difficulties, and endocrine dysfunction are all significant issues in these individuals.

De novo dup(X)(q22.3q26) in a girl with evidence that functional disomy of X material is the cause of her abnormal phenotype

The relationship between phenotype and Xq duplications in females remains unclear. Some females are normal; some have short stature; and others have features such as microcephaly, developmental delay/mental retardation, body asymmetries, and gonadal dysgenesis. There are several hypotheses proposed in the literature to explain this variability. We describe a 7-year-old girl with dup(X)(q22.3q26). The pregnancy was complicated by intrauterine growth retardation, and she was distressed during labor. During her first year she fed poorly and failed to thrive. She has microcephaly, her height is at the 10th centile, and her hands and feet are strikingly small. She is hypotonic and delayed. Asymmetries of muscle power, and of leg and foot length have been noted. She has mild unilateral ptosis. She has some features of Turner syndrome, and multiple other minor anomalies such as flat labia. These are features common to other described females. This report describes our patient in detail and compares her phenotype to those of the other females with Xq duplications, displays our laboratory investigations, and discusses ideas regarding the pathogenesis of phenotype. The duplicated X is of paternal origin. It is inactivated in all cells; however, the distal duplicated portion appears to be active. We suggest that functional disomy of the duplicated X material, due to local escape from inactivation, may be responsible for the phenotype in the affected females.

Molecular cytogenetic analysis of a duplication Xp in a female with an abnormal phenotype and random X inactivation

We describe a female infant with severe abnormal phenotype with a de novo partial duplication of the short arm of the X chromosome. Chromosome painting confirmed the origin of this X duplication. Molecular cytogenetic analysis with fluorescence in situ hybridization (FISH) was performed with YAC probes, further delineating the breakpoints. The karyotype was 46, X dup(X)(p11-p21.2). Cytogenetic replication studies showed that the normal and duplicated X chromosomes were randomly inactivated in lymphocytes. In most females with structurally abnormal X chromosomes, the abnormal chromosome is inactivated and they are phenotypically apparently normal relatives of phenotypically abnormal males having dupX. Therefore, in this case, there is functional disomy of Xp11-p21.2 in the cells with an active dup(X), most likely resulting in abnormal clinical findings in the patient.

Prader-Willi-like syndrome in a patient with an Xq23q25 duplication

We report on a 24-year old woman with an Xq duplication and findings suggestive of Prader-Willi syndrome (PWS). Her birth weight was at the 3rd centile and her birth length was less than the 3rd centile. She was hypotonic and had a weak cry as an infant. There were no feeding difficulties, although her mother reports that as an infant, she was "small for her age." Excessive weight gain began between 3 and 4 years. The patient's development was delayed and she received special education. She has a history of hiding food. She has a sleep disturbance disorder and inappropriate social behavior. At the age of 24 years her height was below the 5th centile and weight >>95th centile. She has physical findings typical of PWS, skin picking, and speech articulation defects. Cytogenetic analysis showed a 46,X,dup(X)(q23q25) karyotype. Fluorescent in situ hybridization (FISH) studies using a chromosome X painting probe demonstrated that the rearrangement was intrachromosomal. The X-chromosome fold scoring technique was used to determine the X inactivation pattern and indicated that some cells expressed the abnormal X chromosome. Results of FISH studies using the SNRPN probe localized to 15q11q13 and DNA studies using the PW71B and SNRPN probes were normal. The duplicated X chromosome, random X inactivation pattern, and the negative molecular studies for PWS indicate that the abnormal X chromosome is the basis of this patient's phenotype. This patient emphasizes the importance of obtaining a karyotype even when a syndrome diagnosable by molecular methods is strongly suspected.

Inherited inverted duplication of X chromosome in a male: report of a patient and review of the literature

Nineteen cases of duplication of segments of the long arm of chromosome X have been published in 13 males and in 6 females. We report an additional case of a male with growth and mental retardation, growth hormone deficiency, compensated primary hypothyroidism, distinctive anomalies of the face, hypoplastic genitalia, and hypotonia in whom inverted duplication of a segment in the long arm of X chromosome was diagnosed, 46,Y, dup (X)(q21.2q13.3), and mosaicism was demonstrated in his mother's X chromosome. The rearranged segment was diagnosed utilizing high resolution G-band technique and FISH studies, using chromosome X total chromosome probe and DNA XIST probe. This appears to be the first report of a patient with duplication of Xq and hypothyroidism.

"De novo" duplication Xq23-->Xq26 of paternal origin in a girl with a mildly affected phenotype

We report a de novo dup(X)(q23-->q26) in a 3-year-old girl with growth retardation, developmental delay, and minor anomalies. X-inactivation in lymphocytes by BRDU labeling showed the abnormal X was late replicating. The androgen receptor assay (HAR) demonstrated a skewed methylation (88.8%) of the paternal allele and a 11.2% methylation of the maternal allele. These data, which suggest the duplication was paternally inherited, are the first parental-origin identification of a duplication Xq. The mild phenotype of the patient may be related to the size and region of the duplication, the low percentage of a dup(X) active detected by the HAR assay, or a combination of these mechanisms.

Molecular cytogenetic identification of four X chromosome duplications

Four cases with previously unidentified X-chromosome abnormalities were studied by standard cytogenetic techniques and FISH in order to demonstrate the origin of the extra segment on the abnormal X chromosomes. All cases were identified as X-chromosome duplications by using a chromosome-specific painting probe. Application of appropriate locus-specific DNA probes as an adjunct to GTG- and RBG-banding proved useful in defining the breakpoints and the extent of the duplications. Although the duplicated X chromosome in female cases was selectively inactivated, as demonstrated by its late-replicating pattern, abnormal clinical findings were manifested in 3 female patients.

Trisomy 10p: report of an unusual mechanism of formation and critical evaluation of the clinical phenotype

A de novo tandem inverted duplication of 10p was diagnosed in a 17-week fetus. The appearance of GTG banded preparations and the results of fluorescence in situ hybridization (FISH) studies are consistent with duplication of the entire arm, including the telomere. The FISH studies also demonstrated the presence of chromosome 10 alphoid repeats at the junction between the inverted segment and the long arm, consistent with the presence of the entire long arm of the abnormal chromosome. Therefore, this is a case of pure trisomy 10p without an associated deficiency of any other chromosome segment. A comparison of the phenotype associated with pure trisomy 10p and trisomy associated with a duplication/deficiency state documented a higher frequency (of borderline significance) of clubfoot and high-arched/cleft palate in the cases of pure trisomy. The frequency of palatal anomalies was observed to be significantly higher in the cases where the breakpoint of the trisomic segment is in the most proximal band (10p11). However, other clinical manifestations were observed inconsistently, even in the cases with pure, nearly complete trisomy 10p. Therefore, a clearly defined trisomy 10p clinical syndrome could not be documented in this study.

Four new cases of inverted terminal duplication: a modified hypothesis of mechanism of origin

We present 4 recently diagnosed cases of inverted tandem duplication with involvement of the respective terminal band. Based on these 4 cases and review of the literature, the term "inverted terminal duplication" is proposed to designate specifically the type of inverted tandem duplication which involves the terminal band. A modification of the previous hypothesis of mechanism of origin is advanced. It is speculated further that a telomeric deletion of a meiotic chromosome followed by a U-type reunion of the chromatids, considered to be the first steps of the proposed mechanism of origin, may not be a rare gonadal event.

Direct transmission of a tandem duplication in the short arm of chromosome 8

A family is described in which a mother and her two children carry a tandem duplication of the short arm of chromosome 8. Their phenotypes are similar and characterised by distinct facial dysmorphism, small stature and mild mental retardation. This is one of the first cases of direct familial transmission of a partial duplication of an autosomal chromosome segment.

Dir dup(X) (q13-->qter) in a girl with growth retardation, microcephaly, developmental delay, seizures, and minor anomalies

In males, duplication of a portion of Xq is associated with multiple congenital anomalies and developmental delay. Most females recognized as having dup(Xq) are phenotypically apparently normal relatives of phenotypically abnormal males; phenotypic normalcy has been attributed to selective inactivation of the duplicated X chromosome. Heretofore, apparently only 5 distinctly phenotypically abnormal females with dup(Xq) have been reported. We report on a 3-year-old girl with developmental delay, growth retardation, microcephaly, minor anomalies, and a seizure disorder who had a nonmosaic, de novo direct duplication of the terminal portion of one X chromosome. In each of 50 lymphocytes examined, the duplicated X chromosome was found to be late-replicating. This case shows that selective inactivation (as reflected by late replication) of the duplicated X chromosome does not inevitably confer phenotypic normalcy on females with dup(Xq), and suggests that other mechanisms must account for the phenotypic differences observed among females with dup(Xq), such as expression of recessive genes on the active X chromosome, incomplete inactivation of some portion of the duplicated chromosomal segment, an imprinting effect, or some combination of these.

Acrodysostosis in two generations: an autosomal dominant syndrome

Acrodysostosis is a rare syndrome characterized by growth retardation, peripheral dysostosis and mental deficiency. X-rays reveal generalized shortening of metacarpals, metatarsals and phalanges, hyperplasia of the first ray of the feet and premature skeletal maturation. Occasionally abnormal interpedicular spinal spaces, increased mandibular angle and hearing loss have been observed. We report a 19-year-old woman and her daughter examined at birth and subsequently at 6 years of age. The clinical and radiological characteristics are those of acrodysostosis. The syndrome is easily recognized at birth. The generalized corporal shortening is progressive and could be due to premature closing of epiphyses. The finding of an affected mother and her daughter support the postulate that acrodysostosis is inherited as an autosomal dominant syndrome.

De novo inverted interstitial ("mirror") duplication of chromosome 8(q13----q24.1) in a liveborn male

We report on a newborn boy with a de novo inverted interstitial duplication of chromosome 8(q13----q24.1). This form of cytogenetic abnormality, in which a mirror image interstitial duplication has occurred, is exceedingly rare. Review of the literature and mechanisms to explain the origin of this type of chromosome aberration are presented. A review of the findings from individuals with partial dup(8q) demonstrate remarkable similarity to the infant we describe.

Acrodysostosis: report of a 13-year-old boy with review of literature and metacarpophalangeal pattern profile analysis

We report on a 13-yr-old boy with acrodysostosis, a review of 30 cases in the literature, and metacarpophalangeal pattern profile (MCPP) analysis. The prominent manifestations (present in greater than 75% of cases) of this condition include nasal and maxillary hypoplasia, peripheral dysostosis, first ray hyperplasia of the foot, acromesomelic brachymelia, decreased interpedicular distance, advanced skeletal maturation and mental retardation. Results of chromosome studies have been normal. An autosomal dominant inheritance pattern was reported in two families. Maternal and paternal ages were 2 and 3 yr, respectively, above the average age of the general parent population, which suggests that advanced parental age may be a factor in the cause of this condition. A characteristically abnormal MCPP was found in our patient and in 16 additional cases studied from the literature. A mean MCPP was developed for the syndrome. MCPP analysis may be useful as a diagnostic tool in patients suspected to have acrodysostosis.

A new syndrome with mental retardation, short stature and an Xq duplication

We describe a new X-linked syndrome of marked short stature, severe intellectual handicap and an unusual facial appearance. High resolution prometaphase banding showed affected males to have an X chromosome tandem duplication; their karyotypes were designated 46,dup(X) (q13.1-q21.1)Y. In carrier females the abnormal X chromosome was late replicating. To verify the duplication, gene dosage studies were performed using an enzyme assay and DNA techniques. Prenatal diagnosis is available for carrier females using chromosome analysis of amniocytes or chorionic villi.

Duplication 17q mosaicism: an infant with features of Ellis-van Creveld syndrome

We describe an infant with multiple dysmorphic features who is mosaic for duplication 17q21.1----qter, owing to a direct tandem duplication. He is the first case with mosaicism for a 17q duplication to be reported. His features are strikingly suggestive of Ellis-van Creveld syndrome.

Robinow syndrome: report of two patients and review of literature

We report two patients with Robinow or fetal face syndrome. We present a thirteen year follow-up on three previously published cases and a review of 32 cases in the literature. The cardinal features of this condition include mesomelic shortening of the forearms, frontal bossing, hypertelorism, wide palpebral fissures, short upturned broad nose with anteverted nares, long philtrum, small chin, brachydactyly, hypoplastic genitalia and a normal karyotype. Development delay and mental retardation was noted in 18% of the reported cases. Early death was identified in about 10% of the cases. Genetic heterogeneity is suggested with autosomal dominant inheritance reported in 8 individuals from 3 families and autosomal recessive inheritance in 8 siblings from 4 families although no clinical differences were identified among those individuals with different inheritance patterns. Male to male transmission was reported in one family. Parental age does not appear to be a factor in the cause of this syndrome.

Reproductive outcomes of paracentric inversion carriers: report of a liveborn dicentric recombinant and literature review

An abnormal infant had a dicentric chromosome 14 with an inverted tandem duplication [46,XY,inv dup(14) (pter----q32.3::q24.2----pter)], thus making him trisomic for the proximal two-thirds of chromosome 14. This abnormality was derived from a maternal paracentric inversion in chromosome 14 [46,XX,inv(14)(q24.2q32.3)]. To our knowledge, this is the first report of a liveborn infant carrying a stable, dicentric product of crossing over within a paracentric inversion loop. A review of the reproductive outcomes of paracentric inversion carriers in the literature suggests that they are at some risk for pregnancy wastage. The risk for liveborn recombinants is small but such births have occurred, at least to female carriers.

De novo direct tandem duplication of the proximal long arm of chromosome 2: 46,XX,dir dup(2)(q11 X 2q14 X 2)

A child is described with a de novo direct duplication of the region 2q11 X 2 leads to 2q14 X 2. She probably represents the first reported case of proximal 2q duplication. The abnormalities included short stature, microcephaly, brachycephaly, depressed nasal bridge, prominent philtrum, congenital glaucoma, and mental retardation.

First trimester fetal karyotyping in twin pregnancy

Fetal chromosome analysis in a twin pregnancy during the first trimester is described. Problems of the reliability of tissue sampling are also discussed. The authors emphasise the advantage of direct cytogenetic analysis from the tissue specimens used for enzyme determination or DNA studies.