Partial duplication of the short arm of chromosome 10. Karyotype: 46,XX,dup(10p)(pter to p12::p12::p12 to qter)

Inv dup del(10p): Prenatal diagnosis and molecular cytogenetic characterization

OBJECTIVE

We present molecular cytogenetic characterization of prenatally detected inverted duplication and deletion of 10p [inv dup del(10p)].

CASE REPORT

A 39-year-old, primigravid woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Amniocentesis revealed a derivative chromosome 10 with additional material at the end of the short arm of one chromosome 10. Simultaneous array comparative genomic hybridization (aCGH) analysis revealed the result of arr 10p15.3 (136,361-451,013) × 1, 10p15.3p12.1 (536,704-25,396,900) × 3 [GRCh37 (hg19)] with a 0.31-Mb deletion of 10p15.3 encompassing ZMYND11 and DIP2C, and a 24.86-Mb duplication of 10p15.3p12.1. The pregnancy was subsequently terminated, and a female fetus was delivered with facial dysmorphism. Postnatal aCGH analysis showed that the umbilical cord had the same result as that of amniotic fluid, whereas the placenta had only the deletion of 10p15.3. Fluorescence in situ hybridization (FISH) analysis of the cord blood confirmed inverted duplication and deletion of 10p. The cord blood had a karyotype of 46,XX,der(10) del(10) (p15.3)dup(10) (p15.3p12.1)dn. Polymorphic DNA marker analysis confirmed a maternal origin of the chromosome 10 aberration.

CONCLUSION

Prenatal diagnosis of inv dup del(10p) with haploinsufficiency of ZMYND11 should include a genetic counseling of mental retardation and chromosome 10p15.3 microdeletion syndrome. aCGH, FISH and polymorphic DNA marker analysis are useful for perinatal investigation of inv dup del(10p).

Small supernumerary marker chromosome originating from chromosome 10 associated with an apparently normal phenotype

Small supernumerary marker chromosomes (sSMC) originating from chromosome 10 are rare. Only seven cases have been documented, and among those three cases were diagnosed prenatally. We reported on another prenatal diagnosis of a de novo mosaic sSMC in an apparently normal female fetus whose mother had conceived with assisted reproductive technology (ART) procedures. G-banding analysis of amniotic cells was performed. Spectral karyotyping (SKY) and fluorescence in situ hybridization (FISH) studies with chromosome 10-specific alphoid satellite DNA probe were used to identify the chromosome 10 origin of the sSMC. Further FISH study with telomeric sequence probes showed that the sSMC lacked a hybridization signal, suggesting that the marker could be a ring chromosome. FISH studies using BAC clone probes specific for the regions within 10p11.2, 10q11.1, and 10q11.2 showed that the short arm breakpoint was located between 29.8 and 30.7 Mb from the 10p telomere, and that the long arm breakpoint was located less than 43.6 Mb from the 10p telomere. The karyotype of the fetus was 47,XX,+mar. ish der(10)(SKY+ CEP 10+, CTD-2130I7+, RP11-89J23-)/46,XX. Oligonucleotide microarray-based copy number variations (CNV) analysis was also performed and showed a 6.7 Mb duplication from 10p11.2 to 10q11.2 (36.2-42.9 Mb) with Affymetrix SNP-array 6.0 genotype: arr cgh. 10p11.2q11.2(CN_519687 --> CN_541524) X 3. At the 1-year follow-up, the baby did not have any findings of the trisomy 10p syndrome. This observation provided further credence to the concept that additional chromosome material of proximal 10p11.2 may not contribute to the trisomy 10p syndrome phenotype.

Identification and characterization of a de novo partial trisomy 10p by comparative genomic hybridization (CGH)

We report the characterization of a de novo unbalanced chromosome rearrangement by comparative genomic hybridization (CGH) in a 15-day-old child with hypotonia and dysmorphia. We describe the combined use of CGH and fluorescence in situ hybridization (FISH) to identify the origin of the additional chromosomal material on the short arm of chromosome 6. Investigation with FISH revealed that the excess material was not derived from chromosome 6. Identification of unknown unbalanced aberrations that could not be identified by traditional cytogenetics procedures is possible by CGH analysis. Visual analysis of digital images from CGH-metaphase spreads revealed a predominantly green signal on the telomeric region of chromosome 10p. After quantitative digital ratio imaging of 10 CGH-metaphase spreads, a region of gain was found in the chromosome band 10p14-pter. The CGH finding was confirmed by FISH analysis, using a whole chromosome 10 paint probe. These results show the usefulness of CGH for a rapid characterization of de novo unbalanced translocation, unidentifiable by karyotype alone.

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.

Familial 10p trisomy resulting from a maternal pericentric inversion

We report a familial recombination of a pericentric inversion of chromosome 10 resulting in 2 affected relatives who had 10p trisomy and 10q monosomy with the karyotypic abnormality designated rec(10) dup p,inv(10) (p11.2q26). Both of these individuals had the typical characteristics of 10p trisomy, however, at birth the proposita had mild facial anomalies suggesting that the distinct facial characteristics may be of postnatal onset in some cases. In addition, the proposita had gastroesophageal reflux causing severe anemia. The phenotype of our patients is compared to 41 patients with 10p trisomy reported in the literature.

Characteristics of structural heart defects in trisomy 9 and their relationship to those in trisomy 13, 18, and 21

The hearts from two live-born full-term infants with nonmosaic trisomy 9 (one complete trisomy 9, one partial trisomy 9) were studied after death. Both demonstrated conal and valvular anomalies associated with ventricular septal defects. These specific malformations are discussed in relation to published cases of trisomy 9 and the cardiac defects of other autosomal trisomies (13, 18, and 21).

A genetic-diagnostic survey in an institutionalized population of 158 mentally retarded patients. The Viaene experience

In this report we summarize the results of a genetic-diagnostic survey of an institutionalized population of 158 severely mentally retarded patients. The etiological study was based on a clinical genetic approach with special attention to dysmorphology and neurological findings. In 72 patients a constitutional cause of their mental impairment was found: a chromosomal abnormality in 21, a Mendelian disorder in 36 (autosomal recessive disorder: 23; autosomal dominant: 12; and X-linked recessive: 1), a MCA/MR syndrome in 9, and a CNS malformation in 6 patients. In 33 patients, a pre- or perinatal cause was found, and 20 patients presented a pre- or perinatal infection of the CNS. Finally, no etiological diagnosis was detected in 28 patients; 6 of them presented a hitherto unclassifiable type of familial mental retardation.

Aplasia cutis congenita: a clinical review and proposal for classification

Aplasia cutis congenita is a condition in which localized or widespread areas of skin are absent at birth. Several distinct clinical subtypes occur, characterized by the location and pattern of skin absence, the presence of associated malformations, and the mode of inheritance. The disorder is seen most frequently on the scalp, often as a solitary lesion without other anomalies. Scalp lesions can be seen in association with limb reduction defects and in association with epidermal and organoid nevi. Lesions may overlie overt or occult embryologic malformations. A form of aplasia cutis congenita occurs in association with placental infarcts or the in utero death of a twin fetus. The condition may be associated with epidermolysis bullosa, specific teratogens or intrauterine infections, or it may occur in the presence of chromosomal abnormalities, ectodermal dysplasias, or other syndromes of malformation. A classification for aplasia cutis congenita is proposed.

Aplasia cutis congenita: a report of 12 new families and review of the literature

Aplasia cutis congenita (ACC) is a heterogeneous group of disorders whose common characteristic is focal absence of skin. In the majority of instances this is limited to the scalp, although other areas of the body may also be involved. Other congenital malformations have been reported to occur with ACC; limb defects appear to be a specific association. Given our experience with ACC, we suggest a classification based on genetically distinct entities. Type I ACC is limited to the scalp. Type II involves body or scalp; IIA involves body or limb defects. Type III is limited to the scalp or limbs. Type IV is associated with epidermolysis bullosa; type IVA is Bart syndrome. Although most reported cases have been sporadic, there are many familial occurrences of all types of ACC. Most published pedigrees are consistent with autosomal dominant inheritance with reduced penetrance, or autosomal recessive inheritance. Careful examination of family members of affected individuals is warranted.

Prenatal diagnosis of trisomy 10 p in a twin pregnancy

A twin pregnancy with trisomy 10 p due to a paternal 10;12 translocation is reported. The prenatal diagnosis steps followed in twin pregnancies are reviewed and the concordant features of trisomy 10 p seen in both fetuses confirm previous reports on the clinical features of this chromosomal defect.

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

Tandem repeats of chromosome material can arise as inverted or as direct duplications. Such duplications of the X chromosome are instructive regarding X-linked genetic determinants of phenotype. We describe a 40-year-old woman with a direct duplication Xq13.3 to Xq27.2, short stature, gonadal dysgenesis, and secondary amenorrhea. Comparison of her phenotype with that of two other women with a direct duplication of part of Xq confirms the existence of statural determinants within the region X13 to Xq21, determinants of ovarian function within X22 to X27, and the X inactivation center within or proximal to band Xq13.3. In humans, direct duplications are more frequent than inverted, but both forms are rare. The mean age of parents is normal in subjects with direct duplications, but is advanced in subjects with inverted duplications. An inverted duplication can arise from a three-break rearrangement that includes a U-type exchange; a similar origin (two breaks and a U-type exchange) and a parental age association can be postulated for dicentric inverted duplications including dicentric isochromosome X.

Duplication 10p in a girl due to a maternal translocation t(10;14) (p11:p12)

We present a dup (10p) due to a t(10;14) (p11;p12)mat with a malformation syndrome in a girl. The analysis of 37 published cases shows that 31 patients (16 males; 15 females) had either a mother or a father carrying a balanced translocation; one case was due to a paternal and another due to a maternal pericentric inversion; two cases were due to de novo translocations; one case had a partial duplication of 10p; and one case had a supernumerary ring chromosome composed of 10p material. The phenotypic spectrum of the condition was analyzed. It is a specific multiple congenital anomalies/mental retardation (MCA/MR) syndrome which includes characteristic facial appearance (dolichocephaly, frontal bossing, short nose with a broad root, highly arched and upswept eyebrows, long philtrum, and thin lips), postnatal growth retardation, severe mental and psychomotor retardation, and several major and minor anomalies. Pseudohermaphroditism seems to be an important anomaly being present in 15 to 20% of affected males. A hypothenar crease together with a transverse crease forming a "crease triangle" seems a helpful sign in the clinical diagnosis of duplication 10p.

Two chromosomal syndromes in the same family: monosomy and trisomy for part of the short arm of chromosome 10

A grandfather with balanced translocation t(1:10) gave rise to three possible combinations involving chromosome 10: balanced translocation and trisomy for part of the short arm 10p13 leads to pter in the second generation, and mono- and trisomy 10p13 leads to pter in the third generation. The clinical signs and symptoms of the present case with monosomy 10p13 leads to pter are compared with those of 9 earlier reported cases with a deleted 10p. Together they represent a clinically recognizable syndrome with antimongoloid eye slant, ptosis, epicanthus, high arched or cleft palate, flat nasal bridge, micrognathia, small round and low-set ears, wide spaced nipples, cardiac and urinary tract abnormalities, hand and foot anomalies, hypoplasia/absence of the olfactory bulbs/tracts, psychomotor and growth retardation. More than 20 cases of the trisomy 10p syndrome have been described earlier. The most constant clinical findings are mental retardation, dolichocephaly, frontal bossing, broad nasal bridge, cheilo-palatoschisis, retrognathia and variable internal malformations. We found, however, the clinical characteristics in this syndrome more variable than for the monosomy 10p13 leads to pter syndrome. Our two cases, representing the eldest and the youngest described, have rather few of the typical characteristics, and few in common with each other. This indicates the difficulty in making this diagnosis on clinical features only without a cytogenetic verification.