Schu Rern Chern

Mosaic Trisomy 7 at Amniocentesis: Prenatal Diagnosis and Molecular Genetic Analyses

OBJECTIVEnTo present prenatal diagnosis and molecular genetic analyses of mosaic trisomy 7.nnnMATERIALS, METHODS AND RESULTSnA 38-year-old primigravid woman underwent amniocentesis at 19 weeks of gestation because of her advanced maternal age. Amniocentesis revealed a karyotype of 47,XY,+7[26]/46, XY[16]. Repeated amniocentesis at 21 weeks of gestation revealed a karyotype of 47,XY,+7[20]/46,XY[17]. Simultaneous cordocentesis revealed a karyotype of 46,XY in 100/100 cultured lymphocytes. Polymorphic DNA marker analyses of uncultured amniocytes and cord blood revealed a diallelic pattern with seemingly equal biparental inheritance of chromosome 7. Repeated cordocentesis and chorionic villus sampling at 23 weeks of gestation revealed a karyotype of 47,XY,+7[2]/46,XY[66] in cord blood and a karyotype of 47,XY,+7 in 24/24 cultured chorionic villi cells. Level II ultrasonography was normal. At 40 weeks of gestation, a 2,708 g normal male baby was delivered. The peripheral blood had a karyotype of 46,XY in 100/100 lymphocytes. Molecular analyses of placenta, urine, buccal swab, and peripheral blood revealed a diallelic pattern and seemingly equal biparental inheritance of chromosome 7 in all tissues. At 3 months of age, he manifested hypopigmented skin and inguinal hernia, but showed normal growth and mental development. Fluorescence in situ hybridization analysis of inguinal hernia sac tissue revealed that 19/100 (19%) of nuclei had three chromosome 7 signals.nnnCONCLUSIONnMosaic trisomy 7 at amniocentesis may be derived from a cell culture artifact from an undetected low level of trisomy 7 mosaicism in uncultured amniocytes, and can be associated with favorable fetal outcome if the blood has a normal karyotype or a very low level of mosaicism and if uniparental disomy for chromosome 7 is excluded.

Prenatal diagnosis of mosaic trisomy 8: Clinical report and literature review

OBJECTIVEnTo present prenatal diagnosis of mosaic trisomy 8 and to review the literature.nnnMATERIALS, METHODS, AND RESULTSnA 34-year-old woman underwent amniocentesis at 16 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 47,XY,+8[6]/46,XY[31]. Repeated amniocentesis at 21 weeks of gestation revealed a karyotype of 47,XY,+8[4]/46,XY[77]. Interphase fluorescence in situ hybridization analysis of uncultured amniocytes showed 25% (5/20) mosaicism for trisomy 8. Array comparative genomic hybridization (aCGH) and quantitative fluorescent polymerase chain reaction (QF-PCR) analyses of uncultured amniocytes revealed no genomic imbalance in chromosome 8. The result of QF-PCR excluded uniparental disomy 8. At 23 weeks of gestation, the woman underwent amniocentesis and cordocentesis at other hospitals. Amniocentesis revealed a karyotype of 47,XY,+8[6]/46,XY[10]. Cordocentesis revealed a karyotype of 47,XY,+8[1]/46,XY[29]. Level II ultrasound findings were unremarkable. The parents decided to continue the pregnancy. A 1373-g male baby was prematurely delivered at 29 weeks of gestation. The peripheral blood had a karyotype of 47,XY,+8[1]/46,XY[29]. The infant had normal growth and mental development at 4 months of age.nnnCONCLUSIONnFetuses with mosaic trisomy 8 are compatible with viability and can have a favorable outcome. QF-PCR and array comparative genomic hybridization have the limitation of detection of low-level mosaicism. We suggest that in instances of repeated amniocentesis for confirmation of mosaic trisomy 8, follow-up investigations should include interphase fluorescence in situ hybridization studies on uncultured amniocytes, uniparental disomy tests, and detailed ultrasound examinations.

A de novo 7.9 Mb deletion in 22q13.2→qter in a boy with autistic features, epilepsy, developmental delay, atopic dermatitis and abnormal immunological findings

We report a 5-year-old boy with mental retardation, autistic features, epilepsy, developmental delay, atopic dermatitis and abnormal immunological findings, carrying a 7.9 Mb de novo deletion of chromosome 22q13.2→qter. This region contains the SHANK3, NCAPH2 and CYP2D6 genes which are associated with T-cell immune response. The present case provides evidence that 22q13 deletion syndrome may be associated with immune system dysfunction in addition to neuropsychiatric disorders.

Unbalanced reciprocal translocations at amniocentesis

OBJECTIVEnTo present perinatal findings, modes of ascertainments, and modes of segregation in unbalanced reciprocal translocations detected at amniocentesis.nnnMATERIALS AND METHODSnBetween January 1987 and July 2010, 40 cases with unbalanced reciprocal translocations were diagnosed by amniocentesis at Mackay Memorial Hospital, Taipei, Taiwan. The 40 cases originated from 29 families; 21 families with one case, 7 families with two cases, and 1 family with five cases.nnnRESULTSnOf 40 cases, 33 (82.5%) presented fetal ultrasound abnormalities and 7 (17.5%) presented no ultrasound abnormalities. Of 40 cases, 36 (90%) had a segregation mode of adjacent-1 2:2 segregation, 3 (7.5%) had a segregation mode of 3:1 segregation with tertiary trisomy, and 1 (2.5%) had a segregation mode of 3:1 segregation with tertiary monosomy. Of 29 families, 7 (24.1%) had de novo translocations and 22 (75.9%) had inherited translocations. In seven de novo cases, the main modes of ascertainments included abnormal ultrasound findings (n = 5) and advanced maternal age (n = 2). In 22 inherited families, the main modes of first ascertainment included abnormal ultrasound findings (n = 8), a previous aneuploid child (n = 8), advanced maternal age (n = 4), parental carrier status (n = 1), and abnormal maternal serum screening results (n = 1). Among 22 inherited families, 9 (40.9%) had a known parental carrier status, but 13 (59.1%) were unaware of parental carrier status at amniocentesis.nnnCONCLUSIONnUnbalanced reciprocal translocations detected at amniocentesis are frequently associated with abnormal ultrasound findings. Prenatal diagnosis of an unbalanced translocation may incidentally detect a balanced translocation in the family. Prenatal diagnosis of fetal structural abnormalities should alert structural chromosome rearrangements and prompt cytogenetic analysis of the fetus and parents if necessary.

Array-CGH detection of a de novo 2.8 Mb deletion in 2q24.2-->q24.3 in a girl with autistic features and developmental delay.

We report a 3 years and 4 months old girl with autistic features, developmental delay, mental retardation, language impairment and dysmorphic features, carrying a 2.8 Mb de novo deletion of chromosome 2q24.2-->q24.3 detected by array-CGH. This region contains two neuronal voltage-gated sodium channel genes SCN2A and SCN3A.

Terminal 2q Deletion and Distal 15q Duplication: Prenatal Diagnosis by Array Comparative Genomic Hybridization Using Uncultured Amniocytes

A 35-year-old, gravida 3, para 2, woman was referred to the hospital at 18 weeks of gestation for amniocentesis because of advanced maternal age and relatives with balanced and unbalanced chromosomal translocations. Her husband and her elder daughter had a balanced translocation of t(2;15)(q37.3;q24.3). Her younger daughter suffered from mental retardation and had an unbalanced translocation of der(2)t(2;15) (q37.3;q24.3)pat. The woman’s karyotype was normal. Prenatal ultrasound during the current pregnancy revealed no structural abnormalities. Genetic amniocentesis was performed at 19 weeks of gestation, and 30 mL of amniotic fluid was aspirated, of which 10 mL was used for array comparative genomic hybridization (aCGH) using uncultured amniocytes and 20 mL was used for conventional cytogenetic analysis using cultured amniocytes. Within 3 days, bacterial artificial chromosome (BAC)-based aCGH demonstrated partial monosomy 2q and partial trisomy 15q [arr cgh 2q37.3q37.3 (RP11-299F2 RP11-875C22) × 1, 15q25.1q26.3 (RP11-10K12 RP11-530H6) × 3] (Figure 1). Conventional cytogenetic analysis revealed TERMINAL 2Q DELETION AND DISTAL 15Q DUPLICATION: PRENATAL DIAGNOSIS BY ARRAY COMPARATIVE GENOMIC HYBRIDIZATION USING UNCULTURED AMNIOCYTES

Prenatal diagnosis and molecular cytogenetic characterization of de novo partial trisomy 7p (7p15.3→pter) and partial monosomy 13q (13q33.3→qter) associated with Dandy-Walker malformation, abnormal skull development and microcephaly.

OBJECTIVEnTo present the prenatal diagnosis and molecular cytogenetic characterization of de novo partial trisomy 7p (7p15.3→pter) and partial monosomy 13q (13q33.3→qter) associated with Dandy-Walker malformation (DWM), abnormal skull development, microcephaly and multiple congenital anomalies.nnnMATERIALS, METHODS AND RESULTSnA 42-year-old woman, gravida 6, para 1, was referred for amniocentesis at 18 weeks of gestation because of her advanced maternal age. Amniocentesis revealed an aberrant derivative chromosome 13, or der(13). The parental karyotypes were normal. Spectral karyotyping showed that the der(13) was derived from a translocation of chromosomes 7 and 13. Fluorescence in situ hybridization using subtelomeric probes revealed three signals of 7pTEL and only one signal of 13qTEL, indicating a translocation between 7p and 13q in the der(13). Array-based comparative genomic hybridization demonstrated partial trisomy 7p (7p15.3-p22.3) and partial monosomy 13q (13q33.3-q34). The karyotype was 46,XY,der(13)t(7;13)(p15.3;q33.3). Polymorphic DNA marker analysis revealed the paternal origin of the aberrant chromosome. Level II ultrasound at 24 weeks of gestation revealed microcephaly, an irregular-shaped skull, DWM, nuchal edema and transposition of the great arteries.nnnCONCLUSIONnSpectral karyotyping, fluorescence in situ hybridization and array-based comparative genomic hybridization are useful for prenatal investigation of the nature of a de novo aberrant derivative chromosome. Partial trisomy 7p (7p15.3→pter) and partial monosomy 13q (13q33.3→qter) can be associated with DWM, microcephaly, abnormal skull development, nuchal edema and cardiovascular defects on prenatal ultrasound.

A 5.6-Mb deletion in 15q14 in a boy with speech and language disorder, cleft palate, epilepsy, a ventricular septal defect, mental retardation and developmental delay.

We report a male patient with speech and language disorder, cleft palate, epilepsy, a ventricular septal defect, mental retardation and developmental delay. Characteristic facial features include low-set ears, a beak-like nose, a prominent nasal bridge, a long philtrum, a narrow forehead, a long face, a pointed chin and dental position abnormalities. Array-comparative genomic hybridization (CGH) analysis demonstrated the presence of a 5.6-Mb deletion in 15q14 (chromosome 15: 3,18,33,000-3,74,77,000bp). The present case provides the evidence that 15q14 deletion outside the region encompassing the CHRNA7 gene can cause generalized epilepsy, and a locus in 15q14 is associated with speech and language disorder.

Prenatal diagnosis and molecular cytogenetic characterization of mosaicism for a small supernumerary marker chromosome derived from ring chromosome 4

OBJECTIVEnTo present prenatal diagnosis and molecular cytogenetic characterization of mosaicism for a small supernumerary marker chromosome (sSMC) derived from ring chromosome, or r(4) by spectral karyotyping (SKY), fluorescence in situ hybridization (FISH), and array comparative genomic hybridization (aCGH).nnnMATERIALS, METHODS, AND RESULTSnA 37-year-old, primigravid woman underwent amniocentesis at 18 weeks of gestation because of advanced maternal age. Amniocentesis revealed a de novo ring-shaped sSMC in 16 of 31 amniocyte colonies. The parental karyotypes were normal. Level II ultrasound findings were unremarkable. Repeated amniocentesis revealed a karyotype of 47,XX,+mar[17]/46,XX[19]. The sSMC was characterized by SKY and FISH, which showed a chromosome 4 origin of the sSMC. aCGH demonstrated a 21.7-Mb gain in the gene dosage encompassing the region of 4p12→q13.2. The sSMC was r(4)(p12q13.2). The fetal karyotype was 47,XX,+r(4)(p12q13.2)[17]/46,XX[19]. The pregnancy was subsequently terminated. The fetus postnatally manifested hypertelorism, epicanthic folds, a prominent nose, a triangular face, low-set ears, clinodactyly of the fingers, and small big toes. Postnatal cytogenetic analyses of fetal and extraembryonic tissues revealed the karyotypes of 47,XX,+r(4)[18]/46,XX[21] in cord blood, 47,XX,+r(4)[20]/48,XX,+r(4),+r(4)[1]/46,XX[9] in umbilical cord, 47,XX,+r(4)[14]/47,XX,+dic r(4)[1]/46,XX[25] in skin, 47,XX,+r(4)[15]/46,XX[25] in amnion, and 47,XX,+r(4)[12]/47,XX,+dic r(4)[1]/46,XX[2] in placenta.nnnCONCLUSIONnSKY, FISH, and aCGH are helpful in genetic counseling of prenatally detected sSMCs by providing the immediate and thorough information on the origin and genetic component of the sSMC.

Inv dup del(9p): Prenatal diagnosis and molecular cytogenetic characterization by fluorescence in situ hybridization and array comparative genomic hybridization

OBJECTIVEnTo present molecular cytogenetic characterization of prenatally detected inverted duplication and deletion of 9p, or inv dup del(9p).nnnMATERIALS, METHODS, AND RESULTSnA 35-year-old primigravid woman underwent amniocentesis at 16 weeks of gestation because of advanced maternal age. Amniocentesis revealed a derivative chromosome 9, or der(9) with additional material at the end of the short arm of one chromosome 9. Parental karyotypes were normal. Level II ultrasound showed ventriculomegaly and normal male external genitalia. Repeated amniocentesis was performed at 20 weeks of gestation. Array comparative genomic hybridization revealed a 0.70-Mb deletion at 9p24.3 and an 18.36-Mb duplication from 9p24.3 to 9p22.1. The distal 9p deletion encompassed the genes of DOCK8, ANKRD15, FOXD4, DMRT1, and DMRT3. Fluorescence in situ hybridization analysis using bacterial artificial chromosome clone probes specific for 9p confirmed that the der(9) was derived from the inv dup del(9p). The karyotype of the fetus was 46,XY,inv dup del(9)(:p22.1-->p24.3::p24.3-->qter)dn or 46,XY,der(9) del(9)(p24.3) inv dup(9)(p22.1p24.3)dn. Polymorphic DNA marker analysis determined a maternal origin of the inv dup del(9p). A 512-g male fetus was subsequently terminated at 22 weeks of gestation with facial dysmorphism. The fetus had normal male external genitalia without sex reversal.nnnCONCLUSIONnFluorescence in situ hybridization and array comparative genomic hybridization are useful to determine the nature of a prenatally detected aberrant chromosome derived from the inv dup del. Male fetuses with inv dup del(9p) and haploinsufficiency of DMRT1 and DMRT3 may present normal male external genitalia without sex reversal.