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2008-03-29-20 Partial trisomy 15 (q24-qter) © Manson www.thefetus.net/
Partial trisomy 15 (q24-qter)

 

Francois Manson, MD.

Fécamp, France.

 

 

Case report

This is a case of partial trisomy 15 (q24-qter) discovered in a fetus of a 32-year-old woman after in vitro fertilization (cryopreserved embryo replacement).

Images 1, 2: Image 1 shows first trimester sonographic appearance of fetal genitalia. Our impression was that the genitalia were female. Nuchal translucency was 1.8 mm (CRL 65 mm) and no anomaly was seen. Due to abnormal maternal triple test (1/58) an amniocentesis was done, but showed male karyotype 46, XY (Image 2).

 

Images 3, 4: Image 3 shows magnified view of the chromosome 15 with a chromosomal satellite (arrow), representing a small piece of non coding chromatin located on the short arm of the chromosome. The satellite chromatin may be localized on acrocentric chromosomes such as 13, 14, 15, 21, and 22 chromosomes, and is common and benign cytogenetical findings without any clinical significance. Image 4 shows male fetal genitalia with extremely short and curved penis leading us to the diagnosis of severe hypospadias.

 

Images 5, 6: Image 5 shows color Doppler view of the male fetal genitalia with hypospadias during fetal miction. Image 6 shows “tulip sign” of hypospadias.

 

Images 7, 8: Image 7 shows prominent pointed fetal forehead. Image 8 shows the prominent forehead without metopic suture and with a bony ridge in the midline.

 

Images 9, 10The images show detailed view of the hyperechoic ridge located in the midline of the fetal forehead.

 

Images 11, 12: Image 11 shows transverse vie of the lateral cerebral ventricle with a cystic appearance of the posterior part of the choroid plexus. Image 12 shows round appearance of the fetal ear.

 

Images 13, 14: Image 13 shows sagittal view of long and prominent fetal philtrum.  Image 14 shows coronal scan of the fetal face with the prominent ridge of the forehead and facial asymmetry.

 

Despite the “normal” karyotype, the anomalies showed above led us to perform further cytogenetical examinations:

1) Parental karyotypes. They were strictly normal without any satellite on chromosome 15.

2) NOR-staining (Silver Nucleolar Organizing Region Staining). In broad outline and as showed below, this technic stains in black the nucleolar organizers located on the short arms of the acrocentric chromosomes.

In our case, the short arm of the chromosome 15, where the satellite was located, was not stained by this technic.

These cytogenetical characteristics insinuated that our “satellite on chromosome 15” was not a benign satellite but a surplus chromosomal material of unknown origin.

3) Multicolor karyotyping.

Images 15, 16: Image 15 shows an example of normal appearance of NOR-staining in a normal patient. Image 16 represents multicolor karyotyping of our case, where chromosome 15 is fully colored in pink, which concludes that the surplus chromosomal material of the chromosome 15 was of the same origin.

 

4) FISH with 15qter probe

Images 17The 15qter probe FISH exhibits three spots in the chromosome 15 (the supernumerary spot is pointed by the arrow).

The final diagnosis was partial trisomy 15 of the 15qter area. Furthermore the exams allowed us to postulate the size of the supernumerary fragment (15q24-qter). Because of constant mental retardation seen in this pathology, the parents opted for the termination of the pregnancy at 30 weeks.

These are the post natal images:

Image 18The image shows facial asymmetry, long philtrum, blepharophimosis, large nose, long upper lip, and down-turned mouth of the fetus after the termination of the pregnancy.

Images 19, 20Image 19 shows prominent occiput, abnormal round ear, long filtrum, and light micrognathia of the fetus after the termination of the pregnancy. The image 20 shows trigonocephaly of the fetus.

 

Images 21, 22: Image 21 shows hypospadias and the image 22 shows abnormal fingers of the fetus..

 

Discussion

Partial trisomy 15 (15q24-15qter) is an extremely rare chromosomal anomaly. Only several cases have been reported in the literature. In addition to constant mental retardation, the most commonly reported features of this condition are:

·        long upper lip;

·        craniostenosis;

·        long philtrum;

·        arched palate;

·        micrognathia;

·        short neck;

·        scoliosis;

·        chest wall deformities;

·        thin extremities;

·        abnormal fingers and toes;

·        hypotonia;

·        convulsions;

·        congenital cardiopathies;

·        abnormal genitalia;

·        abnormal kidneys;

·        abnormal ears;

·        overgrowth.

In our case, the surplus chromosomal material located on the chromosome 15 imitated common and benign finding. Ultrasound findings evoked a need of more particular cytogenetic studies which led to the correct diagnosis.

References

Chandler K, Schrander-Stumpel CT, Engelen J, Theunissen P, Fryns JP. Partial trisomy 15q: report of a patient and literature review. Genet Couns. 1997;8(2):91-7.
Bonati MT, Finelli P, Giardino D, Gottardi G, Roberts W, Larizza L. Trisomy 15q25.2-qter in an autistic child: genotype-phenotype correlations. Am J Med Genet A. 2005 Mar 1;133(2):184-8. 
Roggenbuck JA, Mendelsohn NJ, Tenenholz B, Ladda RL, Fink JM. Duplication of the distal long arm of chromosome 15: report of three new patients and review of the literature. Am J Med Genet A. 2004 May 1;126(4):398-402.
Zollino M, Tiziano F, Di Stefano C, Neri G. Partial duplication of the long arm of chromosome 15: confirmation of a causative role in craniosynostosis and definition of a 15q25-qter trisomy syndrome. Am J Med Genet. 1999 Dec 22;87(5):391-4.
Nagai T, Shimokawa O, Harada N, Sakazume S, Ohashi H, Matsumoto N, Obata K, Yoshino A, Murakami N, Murai T, Sakuta R, Niikawa N. Postnatal overgrowth by 15q-trisomy and intrauterine growth retardation by 15q-monosomy due to familial translocation t(13;15): dosage effect of IGF1R? Am J Med Genet. 2002 Nov 22;113(2):173-7.
Faivre L, Gosset P, Cormier-Daire V, Odent S, Amiel J, Giurgea I, Nassogne MC, Pasquier L, Munnich A, Romana S, Prieur M, Vekemans M, De Blois MC, Turleau C. Overgrowth and trisomy 15q26.1-qter including the IGF1 receptor gene: report of two families and review of the literature. Eur J Hum Genet. 2002 Nov;10(11):699-706.
Engelen JJ, Marcelis CL, Alofs MG, Loneus WH, Pulles-Heintzberger CF, Hamers AJ. De novo "pure" partial trisomy (6)(p22.1-->pter) in a chromosome 15 with an enlarged satellite, identified by microdissection. Am J Med Genet. 2001 Feb 15;99(1):48-53.
Kaneko K, Katabuchi H, Maruta H. Partial trisomy for the distal part of the long arm of chromosome 15--a new syndrome? Nippon Sanka Fujinka Gakkai Zasshi. 1986 Jun;38(6):940-4.
Schnatterly P, Bono KL, Robinow M, Wyandt HE, Kardon N, Kelly TE. Distal 15q trisomy: phenotypic comparison of nine cases in an extended family. Am J Hum Genet. 1984 Mar;36(2):444-51.

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