Down Syndrome Associated with Severe Combined Immunodeficiency: A Case Report
Yildirim, M. S., Artac, H., Reisli, I., Genetic Counseling
Summary: Down syndrome associated with severe combined immunodeficiency: a case report: An 8-month-old-boy was admitted to the hospital because of recurrent bronchopneumonia and gastrointestinal tract infections. On physical examination, he had hypotonia, mental retardation, microcephaly with flat facies, low nasal bridge, small nose, small ears. Laboratory evaluation revealed Down syndrome, lymphopenia, hypogammaglobulinemia, reduced proportions of the peripheral blood lymphocytes with an inverted CD4/CD8 ratio and markedly reduced mitogen response of the lymphocytes. We report here unique case of Down syndrome associated with severe combined immunodeficiency.
Key-words: Down Syndrome - Severe combined immunodeficiency.
Down syndrome is a chromosomal disorder characterized by the presence of an extra chromosome 21. This syndrome is the most common chromosomal abnormality and occurs approximately in 1 of every 700 live births. Down syndrome can usually be diagnosed at birth or shortly thereafter by its dysmorphic features and hypotonia may be the first abnormality (2). Individuals with Down syndrome often have specific major congenital malformations such as those of the heart, particularly the atrioventricular canal, and Hirschsprung disease. In addition the incidence of leukemia is increased in Down syndrome (3).
Severe combined immunodeficiency (SCID) is a rare congenital disorder characterized by little or no immune response. The defining characteristic is a severe defect in both T lymphocyte, B lymphocyte systems and natural killer cell development and function. SCID patients are susceptible to recurrent infections such as pneumonia, meningitis and chicken pox. These infections are usually serious, and may even be life threatening. Opportunistic infection induces organ damage, particularly to the lungs and liver, and is associated with greatly increased morbidity and mortality (1). There are several forms of SCID. Besides the autosomal recessive type, the most common type is linked to the X chromosome, which makes it more common among males (4).
Various forms of immune system abnormalities have been reported in the cases with Down syndrome, up to now. However, we report a first case of Down syndrome occurring concomitantly with SCID. We discuss the relation Down syndrome and immunodeficiency in comparison with the literature.
A 8-month-old boy was admitted to the hospital with a history of fever, cough and respiratory distress. He had a history of recurrent respiratory and gastrointestinal tract infections occurring after 2 months of age. He was the fourth child of consanguineous parents and maternal age was 30 years. Two sisters of the patient who had recurrent respiratory and gastrointestinal tract infections died of pneumonia at one and four year of ages. The patient has a five-year-old brother who is healthy (Fig. 1). The proband had the history of normal spontaneous birth weighting 2800 gr. There were no abnormalities in the prenatal period. On physical examination, he had the facial appearance characteristic of Down syndrome with microcephaly (38 cm, <3%), flat facies, low nasal bridge, small nose and small ears. In addition, there was a simian crease in the right hand, hypotonia and hyperflexibility of joints, psychomotor retardation. He further had oral moniliasis, tachypnea, dyspnea, bilateral crackles, cyanosis and hepatosplenomegaly. Laboratory evaluation revealed hemoglobin 8.9 g/dL, white blood cell count 2.32x10^sup 9^/L, total lymphocyte count 0.938x10^sup 9^/L and platelet count 346x10^sup 3^/µL. A peripheral blood smear showed hypochrome microcytic erythrocytes. The serological tests for cytomegalovirus, Rubella infection, Ebstein-Barr virus, human immunodeficiency virus and herpes virus were all negative. On chest X-ray, there was an ap- pearance of interstitial pneumonitis and no thymus was visualised. The conventional cytogenetic analysis revealed a karyotype of 47,XY +21. …