In the current study, consanguinity was positive in 122 patients (61%) of patients. It was higher than that reported in a study conducted by Shawky et al. [5] at Ain Shams University, Egypt, in which 17 patients (43.5%) had consanguineous parents. Also, our results were higher than a study carried out in Iraq by Arif et al. [6], in which 174 (9.9%) neonates had positive consanguineous marriage and 132 (7.5%) of their patients had positive family history of either metabolic disorders or sudden unexplained death of siblings. In this study, the presentation day ranged from 3 to 12 days with a mean of 6.5 ± 0.7 days after-birth. This was consistent with Shawky et al. [5] who reported that all patients were normal at birth with no complications during delivery, and then they started to develop symptoms at an age ranged from 1 to 10 days with a mean of 3.4 ± 2.2 days.
In our study, the most common manifestation at the time of presentation was sepsis-like manifestations (poor suckling, found in 122 out of 200 cases (61%), followed by respiratory distress in 114 out of 200 cases (57%), then convulsions in 108 out of 200 cases (54%), and vomiting in 104 out of 200 cases (52%)). Our results were in agreement with Shawky et al. [5] and Clarke [8] who reported that sepsis-like symptoms were the most common presentation (26.5% and 15%), respectively. Also, Lunda et al., 2002, reported that the predominant symptoms in neonates suggesting the possibilty of metabolic disorders were convulsions and lethargy [9].
The prevalence of IEM in the current study was similar with Shawky et al. [5] and higher than that found in a study carried out by Selim et al. [10], an Iranian study by Pishva et al. [11], two studies by Elsobky and Elsayed [12] and Riyami et al. [13], an Indian one by Nagaraja et al. [14], an Iraqi one by Arif et al. [6], and two Chinese studies by Sun et al. [15] and Huang et al. [16] (Fig. 1).
Shawky et al. [5] showed that 13/40 (35.5%) suspected neonates were admitted to the El Mahalla Hospital NICU, Egypt, over 1-year duration with sepsis-like symptoms, convulsions, persistent metabolic acidosis, persistent vomiting, and previous sibling death of unidentified causes confirmed to have IEM.
Moreover, Pishva et al. [11] reported that the prevalence of IEM was 14%, which was lower than in our study (Fig. 2). Another study in Karachi by Wajner et al. [17] reported the prevalence of 25.8%. Moreover, several other studies, in Egypt by Elsobky and Elsayed [12], in Brazil by Coelho et al. [18], and in India by Nagaraja et al. [14], reported lower detection rate 6.5%, 3.17%, and 3.2%, respectively.
Additionally, a study done in Oman by Riyami et al. [13] found that 10.8% of their patients were diagnosed with IEMs in high-risk Omani neonates. Likewise, an Iraqi study by Arif et al. [6] with a total number of 1758 symptomatic Iraqi children from birth to early adolescence was analyzed for possible IEM; positive cases were 224/1758, with a rate of detection (12.7%) both of which were lower than in our study.
Amino acid disorder (AA) in our study was accounted as the most common disorder detected, and this was in accordance with Selim et al. [10]. Regarding the AA disorders, urea cycle disorders (UCD) was the most common type in our study, detected in 20/70 (28.5%) of diagnosed cases, with male predominance in 15/20 case (75%). This was in agreement with Shawky et al. [5] as UCD was the most common type with an incidence but with higher level than our study that was 53.8%, and 75% of the diagnosed cases were males. In Shawky et al.’s study [5], the most common IEM was UCD in 7/13, then MSUD in 2/13, followed by MMA and MCAD 1/13. Dissimilar, Gündüz et al. [4] found that UCD was detected only in six cases (11.8%), which were lower than in our study for both.
The second most common amino acid disease in our study was maple syrup urine disease (MSUD), which was detected in 18 cases (25.7%). Our results were higher than in Shawky et al. [5] who diagnose 2/13 (15.4%) cases with MSUD and Selim et al. [10] which was 7.4%. Similarly, Karam et al. [19] in Lebanon identified MSUD in 9.1%; in Fateen et al. [20] in Egypt, it was 1.2%; and Elsobky and Elsayed [12] reported that 10% of children with convulsions had MSUD. This can be explained by the larger number of patients in our study complaining from poor suckling and convulsions, and these presentations are considered as the common symptoms of MSUD.
Furthermore, in our study, organic acidemia was presented in 15/70cases (21.4%), which was higher than in Shawky et al. [5] who detect organic acidemia in 3/40 (7.5%) and in Elsobky and Elsayed [12] who reported organic acidemia in 1.07%.
In our study, one case was diagnosed as B-ketothiolase deficiency; this case was presented on the 1st day after birth with persistent vomiting, convulsion, metabolic acidosis, and hypoglycemia. This patient had one sister with the same disease diagnosed after birth with increased tiglylglycine in urine. In our study, fatty acid oxidation defect was presented in 15/70 cases (21.4 %). This was higher than Riyami et al. [13] in Oman, who detect FAOD in (16%) of cases; Shawky et al. [5] who found FAOD in 1/13 (7.6%); in Selim et al. [10] who found FAOD in 3.4% of patients; and in Arif et al.’s study [6] in Iraq (1.1%).
Our results were lower than that of Vargas et al. [7] who reported that FAOD was detected in 19 patients (28%). These higher results in their study can be explained by their selection criteria which were based on selection of patients with FAOD manifestations only.
In our study, galactosemia was suspected in 3/200 (1.5%) cases. Our results were lower than a study by Fateen et al. [20], who detected galactosemia in (2.5%) of cases. As well, a study by Shawky et al. [5] detected galactosemia in (7.7%) and in a study by Arif et al. [6], who detected galactosemia in 31/1758 (1.76%) of cases. This difference might be explained by that more neonates in their studies presented with clinically suspicious galactosemia and have facilities to do enzymatic assay for galactosemia that was not available in our hospital. Also, they included larger number of patients for longer time.