Poster Abstract Abstract

(Paediatric), #220529111851

Mixed Gonadal Dysgenesis with Isodicentric Y Chromosomes: A Case Series

L Alexis Anand, Paediatric Endocrine unit, Hospital Putrajaya, Malaysia; Nalini M Selveindran, Paediatric Endocrine unit, Hospital Putrajaya, Malaysia; Jeanne Sze Lyn Wong, Paediatric Endocrine unit, Hospital Putrajaya, Malaysia; Janet Yeow Hua Hong, Paediatric Endocrine unit, Hospital Putrajaya, Malaysia

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Isodicentric Y chromosomes forms from intrachromosomal recombination or fusion of sister chromatids following Y chromosome breakage.


Case 1

A 4-month-old boy with ambiguous genitalia had stretched penile length(SPL) 2.4cm with glandular hypospadias and palpable right gonad with empty left side. External Genitalia Score (EGS) was 7 and External Masculinization Score (EMS) was 6.5.

Investigations were 17OHP 33.04nmol/L(12-36), ACTH 2.1pmol/L(1.6-13.9), Renin >550 mU/L(4-89) and Serum Cortisol 239.15(145-619)nmol/L. He was in minipuberty at 3 months with LH 1.7mU/ml, FSH 5.4mU/ml, Testosterone 3.14nmol/L and Anti-Muellerian-Hormone (AMH) 350.3pmol/L(235.5-1125.9).

Ultrasonography revealed right testis with empty left scrotal sac and no Mullerian structures.

Karyotype revealed 73%(45,X) and 27%(46 X idic{Y}) p11.2 with isodicentric Chromosome Yq.


Case 2

A 4-month-old boy presented with ambiguous genitalia. The SPL was 2.5cm with perineal hypospadias. The right testis is palpable at inguinal region and left testis impalpable. EGS was 5.5 and EMS was 5.5.

Investigations were 17 OHP 19.9nmol/L, Aldosterone >3656pmol/L, Renin 128.9mU/L and serum cortisol 255nmol/L. Investigations post-delivery revealed minipuberty with FSH 4.84IU/L, LH 6.59IU/L, Testosterone 5.86nmol/L, and estradiol 43pmol/L. AMH at 4 months was 435.8pmol/L.

Ultrasound abdomen showed embedded penile with bilateral inguinal testis and no Mullerian structures.

FISH with SRY gene revealed first cell line(74.5%) of isodicentric chromosome Y and the second cell line(25.5%) of 45,X.


Patients with isodicentric Y chromosomes have various presentations necessitating follow-up to monitor growth, puberty, fertility, gonadal dysgenesis, and short stature.

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