Academic journal article Genetic Counseling

PARTIAL TRISOMY 1q (1Q42.13[arrow Right]qter) AND PARTIAL MONOSOMY 6q (6Q27[arrow Right]qter) IN A GIRL WITH SINGLE MEDIAN MAXILLARY CENTRAL INCISOR, CORPUS CALLOSUM DYSGENESIS AND DEVELOPMENTAL DELAY

Academic journal article Genetic Counseling

PARTIAL TRISOMY 1q (1Q42.13[arrow Right]qter) AND PARTIAL MONOSOMY 6q (6Q27[arrow Right]qter) IN A GIRL WITH SINGLE MEDIAN MAXILLARY CENTRAL INCISOR, CORPUS CALLOSUM DYSGENESIS AND DEVELOPMENTAL DELAY

Article excerpt

Summary: Partial trisomy 1q (Iq42.13[arrow right]qter) and partial monosomy 6q (6q27[arrow right]qter) in a girl with single median maxillary central incisor, dysgenesis of corpus callosum and developmental delay: A 3-year-old girl presented with mental retardation, developmental delay, seizures, hypotonia, brachycephaly, a triangular face, single median maxillary central incisor (SMMCI), prominent forehead, down-slanting palpebral fissures, hypertelorism, a higharched palate, micrognathia and low-set ears. Computed tomographic scans revealed corpus callosum dysgenesis and hypoplasia of bilateral frontal sinuses. Oligonucleotide-based array comparative genomic hybridization analysis revealed a ~20.7-Mb duplication of lq42.13[arrow right]qter and a ~3.6-Mb deletion of 6q27[arrow right]qter. The karyotype of the girl was 46,XX,der(6)t( 1 ;6)(q42. 13;q27)pat. Mutational analysis of the patient revealed no mutation in the genes o(SHH, SIX3 and TGIF. The present case adds unbalanced chromosome aberration of partial trisomy lq and partial monosomy 6q to the list of genetic conditions associated with SMMCI.

Key-words: Corpus callosum dysgenesis - Monosomy 6q - Single median maxillary central incisor - SMMCI -Trisomy 1q

INTRODUCTION

The 6q27 subtelomeric deletion syndrome is a recognizable syndrome characterized by mental retardation, dysmorphic features, ear anomalies, epicanthic folds, hydrocephalus, abnormal corpus callosum, brain anomalies, seizures, hypotonia, microcephaly and vertebral anomalies (4, 7, 12, 22, 26, 37, 42, 45, 46). Distal partial trisomy lq with a duplication of lq42-»qter has been reported to be associated with a mild phenotype with a triangular face, low-set ears, short stature, psychomotor retardation, cardiac defects, macrocephaly, large fontanelles, prominent forehead, broad flat nasal bridge, high-arched palate and micro/retrognathia (2, 21, 44, 49, 52). Here, we present partial trisomy lq (lq42.13-*qter) and partial monosomy 6q (6q27-»qter) in a girl with single or solitary median maxillary central incisor (SMMCI), corpus callosum dysgenesis and developmental delay. To our knowledge, this is the first report of SMMCI associated with a duplication of lq42-»qter and a 6q27 subtelomeric deletion.

CASE REPORT

The 3-year-old girl was the first child of a 28-year-old mother and a 30year-old father at her birth. She was delivered at 38 weeks of gestation with a body weight of 2,600 g (10-25th centile), a body length of 45 cm (< 3rd centile) and a head circumference of 31 cm (3rd- 10th centile) after an uncomplicated pregnancy. At the age of one year, she was referred to the hospital because of seizures, hypotonia, dysmorphic features, microcephaly, developmental delay and bilateral subluxation of the hips with a weight of 8.5 Kg (15-50th centile), a length of 68 cm (< 3rd centile) and a head circumference of 43.8 cm (15th centile). Cytogenetic analysis of the patient revealed a derivative chromosome 6 with an extra chromosomal segment at the end of one chromosome 6q. The father was found to have a karyotype of 46,XY,t(l;6)(q42.1;q27), and the mother had a karyotype of 46,XX. Oligonucleotide-based array comparative genomic hybridization (aCGH) analysis using Oligo HD Scan array (CMDX, Irvine, CA, USA) showed a 20.7-Mb duplication of Iq42.13q44 [Iq42.13q44 (226,613,849 - 244,163,895 bp)x3] and a 3.6-Mb deletion of 6q27q27 [6q27q27 (167,320,894 - 170,899,992 bp)xl] (NCBI build 36, March 2006) (Fig. 1). The girl's karyotype was 46,XX,der(6)t(l;6)(q42.13;q27)pat. At the age of 1 year and 8 months, her body weight was 8.4 Kg (3rd centile), and body length was 70 cm (< 3rd centile). The heart echograms were unremarkable, the brain computed tomographic (CT) scans revealed corpus callosum dysgenesis, and the skull CT scans revealed brachycephaly, hypoplasia of bilateral frontal sinuses and SMMCI (Fig. 2). At the age of 3 years, her body weight was 10.5 Kg (< 3rd centile), body length was 88 cm (3rd centile), and she manifested moderate mental retardation, developmental delay and craniofacial dysmorphism of brachycephaly, a triangular face, SMMCI, prominent forehead, down-slanting palpebral fissures, hypertelorism, a high-arched palate, micrognathia and low-set large ears (Fig. …

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