Clinical and cytogenetic studies on Egyptian children with PWS were undertaken by El-Harouni et al. (1996). They analyzed 10 Egyptian children (eight boys and two girls) who presented with obesity, mental retardation and behavioral problems. Clinical evaluation, pedigree analysis, analysis of intelligence and development quotients, electroretinogram studies, and cytogenetic analysis were performed for the patients. The patients were scored for their diagnostic criteria based on the scoring system of Holm and all of them were seen to fulfill the requirements for diagnosis of PWS. Cytogenetic studies showed three of the patients (30%) to have the classical deletion in the 15q11-q13 region. One of these patients also showed a translocation at t(15;20, q15;q13.3). Such a mutation had not been reported before for PWS. Three other cases showed other chromosomal abnormalities involving chromosome 15. These included duplication of the 15p and 22p regions, breaks in the 15q region, and double satellites of the chromosome. The remaining four cases did not show any cytogenetic abnormality, and El-Harouni and colleagues (1996) ascribed these cases to uniparental maternal disomy. [El-Harouni AA, Mahmoud AM, Kamel, AK, Shehab, M. Prader-Willi syndrome in Egyptian children clinical and cytogenetic studies. Egyptian J Pediat. 1996; 13(3-4):133-44.]

Farag et al. (1999) conducted a diagnostic evaluation of craniofacial anomalies in 25 patients (8 females, 17 males). In all, 15 patients had chromosomal abnormalities. Five patients had unbalanced chromosome rearrangements and six had chromosome markers. Three patients were FISH-positive for William syndrome and one was positive for Prader-Willi syndrome. Ten patients had monogenic disorders. Five were diagnosed as craniosynostosis syndromes.

Shawky et al. (2001) studied the phenotypic expression of PWS in 32 index cases that presented with obesity and/or hypogonadism. Holm's scoring system was used to identify the major and minor criteria for PWS. Full clinical history was taken for the patients, and clinical assessment and cytogenetic studies were performed. Only 14 patients were found to fulfill the criteria for diagnosis of PWS. The sex ratio was 11 males to 3 females. Shawky et al. (2001) proposed that the male preponderance could be due to the early identification of male hypogenitalism. None of the cases showed a positive family history. Among the major criteria analyzed, neonatal central hypotonia with poor suckling, excessive weight gain, central obesity, global developmental delay, and hyperphagia were found in all the patients. With regard to the minor criteria, the most frequent were decreased fetal movements or infantile lethargy or weak cry, temper tantrums, sleep disturbances, and small hands; all present in 71.4% of the patients. Mental retardation was predominantly in the mild range (71.4%). All male patients had hypogonadism. Behavioral problems included temper tantrums (71.4%), obsessive behavior (57.1%), violent outbursts (35.7%), and possessiveness and stubbornness (35.7%). Other anomalies found in the patients included ocular anomalies (28.6%), thick viscous salive with crusting at the corners of the mouth (57.1%), speech articulation defects (14.28%), and skin picking (42.8%). The 15q11-13 deletion was proved in three out of nine patients who underwent high resolution PLC. Shawky et al. (2001) concluded that correct diagnosis of PWS could be effectively made by combining clinical diagnostic criteria with molecular genetics. [Shawky RM, el Sedfy HH, Zaki OK, Mahmoud HM. Phenotypic expression of Egyptian patients with Prader-Willi syndrome. Egyptian J Med Hum Genet. 2001; 2(1): 55-66.]

Murthy et al. (1995) reported two cases of non-deletional Prader-Willi syndrome (PWS). Case 1 is a 9-yr-old female patient with classical features of the syndrome and cytogenetically normal chromosome 15. DNA analysis using polymorphic probes for Prader-Willi Critical Region (PWCR) showed absence of paternal alleles while maternal uniparental isodisomy (UPisoD) was confirmed. This is the first report of non-deletional PWS with uniparental disomy (UPD) in the population of Kuwait. The second case with Prader-Willi syndrome-like features had normal chromosome 15 but showed familial complex chromosomal rearrangement (CCR) involving chromosomes 13, 19, and 20 inherited from his mother. No paternal deletion or UPD disomy was observed after DNA molecular analysis.

Greenwood and Small (1990) recorded the findings of severe early onset periodontitis in a 12-year old Saudi girl presenting with Prader-Willi Syndrome. The patient had been born in breech position and gradually developed obesity in the second year of her life. Upon examination, she was found to have a short stature, marked obesity, a fish mouth appearance, and reduced intelligence. She had been diagnosed with diabetes, and was on insulin therapy. Dental findings included a prominent premaxilla, bimaxillary proclination, a class II division I incisor relationship, increased overjet, anterior open bite, and considerable spacing of upper and lower anterior teeth. There was severe generalized loss of attachment. She underwent deep scaling for her periodontal disease, resulting in marked improvement. Chromosomal study did not demonstrate any abnormality, and chromosome 15 banding pattern was normal. However, she was still considered to fit the diagnosis of Prader-Willi Syndrome.

Salako and Ghafouri (1995) report the case of a 5-year-old child with Prader-Labhart-Willi syndrome. The child presented with a severe form of dental caries.

In 1999, Iqbal and colleagues used fluorescent in situ hybridization (FISH) and diagnosed four patients with Prader-Willi Syndrome [del(15)(q11.2q12)], 4 patients with DiGeorge syndrome [del(22)(q11.2q11.23)] and 4 patients with Williams syndrome [del(7)(q11.23q11.23)]. High-resolution chromosome analysis in all these patients was either normal or inconclusive but all the syndromes were confirmed using FISH.