Academic journal article Genetic Counseling

ARRAY-CGH AND CLINICAL FINDINGS IN A PATIENT WITH A SMALL SUPERNUMERARY R(8) MOSAICISM

Academic journal article Genetic Counseling

ARRAY-CGH AND CLINICAL FINDINGS IN A PATIENT WITH A SMALL SUPERNUMERARY R(8) MOSAICISM

Article excerpt

INTRODUCTION

Complete trisomy 8 is a well-known cytogenetic syndrome and is a condition that is usually fatal (15, 25). In live births, trisomy 8 syndrome is thought to almost always be associated with mosaicism. Mosaic trisomy 8, also known as Warkany syndrome (36), is a well-characterized entity. The phenotype varies greatly from almost normal to severe mental and physical disabilities and malformations. Clinical findings include frequently agenesis of the corpus callosum, joint contractures, bone dysplasia, absent or dysplastic patellae, bulbous nose, micrognathia, prominent forehead, malformed ears, deep set eyes, dysmorphic face, thick lips, camptodactyly, clinodactyly, vertebral and hip anomalies, ocular, cardiac and renal malformations, and musculoskeletal abnormalities overlapping with trisomy 8 syndrome (2,7,12,16, 24,27,28,33,34,37,38).

sSMC are defined as structurally abnormal chromosomes. sSRC are a clinically significant group of sSMC. Therefore, SMCs and SRCs originating from chromosome 8 represent a heterogeneous group due to the difference of the chromosomal segment implicated that has been reported in at least 32 cases (4,13,18,34).

Until recently, the great variety of marker chromosomes and difficulties with their identification has presented a problem for cytogenetic and clinical interpretation of the karyotype (8,14,18,20). At present, molecular cytogenetic methods of chromosome analysis enable precise characterization of such abnormalities providing knowledge necessary for estimation of their genetic risk. However, some patients remained unsolved when singleor dual-color FISH techniques using WCPor region-specific DN A probes were performed ( 10,11 ) and it was reported that array-CGH enables faster results than standard cell culture and metaphase analysis and has the capability of detecting mosaicism at levels as low as 7% (22,26).

Herein, we present our cytogenetic analysis results of a patient with de novo mosaic ring chromosome 8-derived SRC. We applied array comparative genomic hybridization (array-CGH) in order to precisely define the extension of the duplicated region. In addition, clinical features are described with cytogenetic finding to estimate genetic risk of identified markers.

CLINICAL EVALUATION

The patient was a 2 years old male who is the 2nd child of healthy non-consanguineous parents. He was bom at full-term by normal vaginal delivery after an uneventful pregnancy. He had anoxia at birth. He had also atypical facial appearance. There were no similar phenotypes among the family members. The elder brother of the patient is healthy and 5 years old with normal phenotype.

Firstly, a sixteen-days old boy was referred to the Pediatric Endocrinology clinic because of congenital anomaly and genital ambiguity. On physical examination, his weight, height and head circumference have reported as 3360 g (25-50th percentile), 51 cm (50th percentile) and 34 cm (< 3th percentile), respectively. The anterior fontanel was open 0.5 x 0.5 cm, and microcéphalie and the posterior fontanel was closed. He was hypotonic and hypoactive. He is 2 years old now. He still has dysmorphic features. Weight is 12 kg (25-50 percentile), height 90 cm (50th percentile) and head circumference 44.5 cm (< 3th percentile).

He has multiple congenital anomalies including hypertelorism, micrognathia, long philtrum, broad nasal root, distinct big ears loops and turned in front-inside, nystagmus, exophtalmus on the right eye, long black eyelashes, mild ptosis on the left eye and high myopia (-17 diopters) upon ophthalmological examination. He had inspiratory stridor from laryngomalacia.

Genito-urinary examination revealed penile hypospadias and cordia, penile length was 3.5 cm and unique urogenital orifice. There were no palpable gonads in the scrotum and present in inguinal channel. Pelvic USG revealed posteriorureteral valve (PUV) and 3rd degree vesicoureteral reflux (VUR). …

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