Atypical Down syndrome phenotype with severe developmental delay, hypertonia, and seizures in a child with translocation trisomy 21

Abstract

An infant is reported who presented with a de novo 21;21 translocation trisomy 21 and an atypical phenotype for Down syndrome (DS). Findings included microcephaly, small stature, downslanting palpebral fissures, absent Brushfield spots, moderate micrognathia, left ptosis, left torticollis, severe developmental delay, seizures, and hypertonia. Further clinical evaluation using both the diagnostic criteria for DS and the Jackson checklist of 25 signs was inconsistent with the diagnosis for DS. Blood karyotype revealed: 46,XX,+21,dic(21;21) (p11.2;p11.2). Fluorescence in situ hybridization (FISH) analysis confirmed the trisomy 21 translocation. Both parents had normal karyotypes. Chromosome and FISH analyses were performed on skin fibroblasts. These studies revealed mosaicism for a translocation trisomy 21 cell line as wel as a second cell line consisting of one normal chromosome 21 and a ring chromosome 21 derived from translocation 21q21q which appeared to have a deletion of the critical region for DS involving the distal portion of the thelong arm of chromosome 21. The chromosome findings illustrate an atypical phenotype in the spectrum of mosaic DS and suggest possible mechanisms for the variability of the phenotype. It also emphasizes the importance of evaluating other tissues for mosaicism when presented with atypical clinical findings.

Dystonia in a patient with ring chromosome 21

“…This report, documenting a second individual with torticollis and ring chromosome21, 21 provides supportive evidence for a possible role of the 21q22 locus in the pathogenesis of cervical dystonia.…”

“…A previous report describes a patient with an atypical Down syndrome phenotype and torticollis at age 5 weeks 21. The karyotype was a mosaic of translocation trisomy 21 and ring chromosome 21.…”

Experience with Clinically Diagnosed Down Syndrome Children Admitted with Diarrhea in an Urban Hospital in Bangladesh

“…Case report forms (CRF) were developed and finalized for data acquisition. Characteristics analyzed included sociodemographic (age, gender, height and weight, type of residence, source of drinking water, and formula feeding), clinical signs (dehydration and temperature), clinical diagnosis (sepsis, pneumonia, chronic lung disease, pulmonary TB, severe acute malnutrition, congenital heart diseases (CHD), motor developmental delay within 0–59 months (neck control, sitting, standing with or without support, and walking) [ 8 ], hypothyroidism, hospital acquired infection (HAI) [ 9 , 10 ]), and outcome during discharge. Sepsis was defined as presence or presumed presence of infection with hypothermia (≤35.0°C) or hyperthermia (≥38.5°C), tachycardia, tachypnea, and abnormal WBC count (>11 × 10 9 /L or <4 × 10 9 /L or band and neutrophil ratio ≥0.10) [ 11 , 12 ].…”

Thyroid Dysfunction in Down syndrome Patients; Clinical and Chromosomal Correlation

“…The incidence of DS in Duhok province of Iraq is 1\960, which is within the world average. 1,2 Down syndrome is associated with mental retardation, metabolic and endocrine disorders, several congenital anomalies, including cardiovascular and gastrointestinal systems. The most frequent endocrine disorders associated with DS are thyroid related disorders.…”