Leading Article Cytogenetic testing in paediatrics: Some aspects of the Sri Lankan scenario

Cytogenetic testing or chromosome culture and karyotyping was introduced to Sri Lanka in October 1983 with the establishment of the Human Genetics Unit of the Faculty of Medicine, University of Colombo. In 2006 a private sector laboratory too, entered the field. There has been an upward trend in the number of cytogenetic tests performed in Sri Lanka since 1983 (Figure 1). At the same time an unknown number of samples are sent abroad for testing. Figure 2 Karyogram of the baby at 450 band banding level showing an unbalanced translocation between chromosome no.14 and chromosome no.21. The karyotype is 46, XY, t (14; 21)

Autosomal dominant hereditary ataxia in Sri Lanka

Background Spinocerebellar ataxias (SCA) are a group of hereditary neurodegenerative disorders. Prevalence of SCA subtypes differ worldwide. Autosomal dominant ataxias are the commonest types of inherited ataxias seen in Sri Lanka. The aim of the study is to determine the genetic etiology of patients with autosomal dominant ataxia in Sri Lanka and to describe the clinical features of each genetic subtype. Methods Thirty four patients with autosomal dominant ataxia were recruited. For every patient the following was done: recording of clinical details and genotyping for SCA 1, 2, 3, 6, 7, 8, 12, and 17. Results Sixty one per cent of the subjects were identified as SCA1. One subject had SCA2, 12 remain unidentified. Mean age at onset was 34.8 ± 10years for SCA1 and 32.7 ± 9.8 for non SCA1. 76% of SCA1 patients and 50% of non SCA1 were using walking aids. Quantification of symptoms and signs were similar in the SCA1 and non SCA1 groups. Clinical depression was evidenced in 68.4% of SCA1 and 75% non SCA-1 patients. Mean CAG repeat length in SCA1 patients was 52.0 ± 3.8, with greater anticipation seen with paternal inheritance. Conclusion SCA1 was the predominant subtype and showed similar phenotype to previous reports. However, disease severity was higher and depression more prevalent in this population than previously described

A Sri Lankan child with 49,XXXXY syndrome

Pentasomy 49,XXXXY is a rare sex chromosome disorder usually presenting with ambigous genitalia, facial dysmorphism, mental retardation and a combination of cardiac, skeletal and other malformations. The incidence of the condition is estimated to be 1 in 85,000 male births. Previously, this condition was identified as a Klinefelter variant. The condition is suspected in a patient, by a combination of characteristic clinical findings, and the diagnosis is confirmed by chromosome culture and karyotyping. In the case we report here, the main presentation of ambiguous genitalia led to a suspicion of a sex chromosome aneuploidy which was subsequently confirmed by chromosomal analysis

A child with mosaicism for deletion (14)(q11.2q13)

In this case report we describe a child with a de novo deletion in the (q11.2q13) region of chromosome 14. The child presented with dysmorphic features - anophthalmia, microcephaly, and growth retardation. Cytogenetic studies showed mosaicism. The karyotype was 46,XX,del(14)(q11.2;q13) [16] /46,XX [9]. We compared the features observed in this child with that of others with the same deletion reported in scientific literature and found that this is the first report of a child mosaic for this deletion. It is also the first time it has been reported in association with anophthalmia

A child with mosaicism for deletion (14)(q11.2q13)

In this case report we describe a child with a de novo deletion in the (q11.2q13) region of chromosome 14. The child presented with dysmorphic features - anophthalmia, microcephaly, and growth retardation. Cytogenetic studies showed mosaicism. The karyotype was 46,XX,del(14)(q11.2;q13) [16] /46,XX [9]. We compared the features observed in this child with that of others with the same deletion reported in scientific literature and found that this is the first report of a child mosaic for this deletion. It is also the first time it has been reported in association with anophthalmia

An adolescent with 48,xxyy syndrome with hypergonadotrophic hypogonadism, attention deficit hyperactive disorder and renal malformations

48,XXYY is a rare sex chromosome aneuploidy affecting 1 in 18,000 to 50,000 male births. They present with developmental delay, hypogonadism, gynecomastia, intention tremors, and a spectrum of neurodevelopmental and psychiatric disorders. At one time this condition was considered a variant of Klinefelter syndrome. In clinically suspected cases, 48,XXYY syndrome can be diagnosed by chromosome culture and karyotyping. This patient presented with hypergonadotrophic hypogonadism, attention deficit hyperactive disorder, and renal malformatons. Klinefelter syndrome was clinically suspected. The karyotype confirmed the diagnosis of 48,XXYY syndrome. This is the first reported case of 48,XXYY syndrome from Sri Lanka